Document vyjKYwGkEp5yznXZJgXpL1z59

UNITED STATES GYPSUM COMPANY 300 West Adams Street, Chicago 6, Illinois a eo o u oo 0* TABLE OF CONTENTS Plaster Bases Basecoat Plasters Finishing Plasters Roclclath Lathing Systems Metal Lathing Systems Plaster Problems and Remedies How to Inspect a Plaster Job PAGE 9 31 43 57 75 87 101 > iu Gypsum.. .the basic material for lathing and plastering What is Gypsum? Gypsum is one of the most common minerals of the earth. Monmetallic, it is usually in the form of grey or white rock, found in veins varying from a few feet to 20 and 30 feet in thickness. Chemically, gypsum is a mineral composed of calcium sulphate combined with water of crystallization. This "dry" water makes up approximately 20 percent of the weight of raw gypsum rock, and it is this feature which gives gypsum its fire-protective qualities and makes it so adaptable for the manufacture of building materials. 5 BB013 0063 v9 oo cioaa How Gypsum is Processed After gypsum is mined or quarried, it is crushed and ground and then calcined (or cooked) to remove the greater part of the chemically combined water. This calcined product, or Plaster of Paris, is the basic ingredient of all gypsum materials. Com bined with other materials and water, it is used for the manu facture of gypsum lath, partition tile and gypsum plasters. When it is mixed with water to make gypsum lath or to make a plaster mix on the job, it re-absorbs the water removed in proc essing and reverts to gypsum rock. This recombination with water is why gypsum materials give such excellent tire protec tion to buildings. V How Gypsum Protects Against Fire When fire heats a gypsum wall or ceiling to about 212 F., the water of crystallization is gradually converted into steam. The water of crystallization effectively retards the spread of flame. For instance, in an average room 10 feet square finished with gypsum lath and plaster, the heat of a fire could convert the water of crystallization in the gypsum into sufficient steam to fill the room three time;. The back of the gypsum wall will not be much hotter than 212 F. until all the water is gone-- a slow process. This protects the wood framing, which doesn't start to bum until about 400 F. Setting Action o# Gypsum Water is added to gypsum plaster on the job until the material is sufficiently plastic to spread easily under the trowel. After it is applied, the gypsum particles re-absorb part of the water from the mix and the plaster reverts through crystallization to the chemical form it originally had when taken from the ground. The balance of the mixing water is dried out of the plaster slab through ventilation and evaporation. When crystals begin to form in gypsum plaster, it starts to harden; tnis is known as the "setting action" of gypsum. Gypsum which has been calcined begins to set soon after water is added. RED TOP--Stabilized Set Mill addition of special ingredients developed by U3G Research has resulted in the famous ''Stabilized Set" of ail Red Top plasters. Red Top minimizes variability m sets often caused by sand and water impurities which would accelerate or retard the set of ordinary plaster. Whether machine or hand mixed-- applied over metal, wood, gypsum, insulating lath, cement block, brick, clay or gypsum tiie--a scratch or brown coat of Red Top mixed with sand or lightweight aggregates (vermiculite, perlite) sets more uniformly. It also sets to more uniform hardness, providing a better surface for application of white coat. The set progresses evenly from the base out to the surface. Why gypsum is better for building In addition to its outstanding fire-protective qualities, the mineral gypsum will not rot nor decay and combines light weight with strength. It builds durable walls that last a lifetime, and may be economically adapted to any architectural design. B B O lia 0 0 6 6 Plaster Bases ROCKLATH plaster base PYROBAR and othar Masonry Plaster Bases USG COLOR-RITE Metal Lath and Accessories 10 17 21 Proper use and application of USG plaster bases is important in the construction of strong durable finished wails and ceilings. A secure bond between the plaster and plaster base is essen tial to develop strength and resistance to abuse and cracking. Gypsum piaster adheres to a plaster base because a bond is developed which virtually makes the two materials a solid unit. A "mechanical" bond is formed when plaster is pressed through the mesh or holes of the lath, forming keys on the other side. The keys actually 'rivet" the plaster and lath together. This mechanical bond results when plastering over metal lath or perforated gypsum lath. A "suction" bond is formed when gypsum plaster is applied over gypsum lath, and masonry bases. In this case the tiny needle-like plaster crystals penetrate into the surface pores of the base by suction. When the plaster sets, the base becomes "welded" to the plaster. When perforated gypsum lath is used, both suction and mechanical bonds are developed. 9 BB013 0067 ROCKLATH Plaster Bases Plain ROCKLATH Plaster Base is a gypsum lath made in sheet form in thicknesses oi Ys in. and Y> in. It consists ot a core oi gypsum pressed and rolled between two layers oi special absorptive paper, and is the standard ot excel lence tor receiving gypsum base coat plaster. ADVANTAGES Fireproof-- Rocklath has an incom bustible gypsum core and will not transmit temperatures much over 212 degrees F. until completely cal cined. Resistant to Sound Transmission -- Wood stud partitions with Rocklath and gypsum plaster on both sides have a high resistance to sound transmission. {See Rocklath Resili ent System page 60 tor higher sound transmission resistance.) Strong Bond--Gypsum plaster bonds to Rocklath with a saietv factor of 144--tar higher than required to meet usual construction standards. Structurally Strong--Large units add resistance to racking of framing members. Durable-- Not harmfully affected by decay, dry rot or normal moisture. Will not attract vermin. Economical--The low cost of ROCK LATH, its ease and speed of erection and savings in plastering are out standing. LIMITATIONS OF USE 1. Gypsum iath, Y% in. thick, is de signee for supports not to exceed 16 in. o.c. For iraming spaced more than 16 in. o.c. but not more than 24 in. o.c., *'2 in. thick Rocklath should be used. 2. Cse with gypsum plaster only. Bond between lime or portiand cement plaster and Rocklath is inadequate. 3. Gypsum lath and plaster, painted with 3 coats of lead and oil, has a vapor permeability of about Perms (grains of water per square foot per hour per inch of mercury vapor pressure difference). For higher resistance to vapor transmission, use Insulating Rocklath plaster base. 4. Do not use in areas exposed to excessive moisture for long periods of time. Use galvanized metal lath and portiand cpment-lime plaster. 5. Where one hour nre resistive rat ings are required, Perforated Rock lath plaster base should be used. Perforated ROCKLATH is identical to plain Rocklath ex cept that 'I in. round holes are punched tnrough the lath 4 in. o.c. These perforations allow the applied plaster to '`mushroom" through the BB013 0068 10 holes and form "rivets" to mechani cally key the plaster to the Rocklath. providing both mechanical and auction bonds. ADVANTAGES Same as plain Rocklath but with higher fire rating. Gives one hour fire rating on partitions with H in. gyp- sum piaster sanded 1:2-1.2 by weight, or gypsum-perlite piaster 100 lbs. to V/ cu. ft. and a one hour rating on ceilings, with gypsum-perlite plaster proportioned 100:2}^. LIMITATIONS OF USE Same as for plain Rocklath plaster base, except perforated Rocklath should not be used on ceilings with Resilient Rocklath clips or other side suspended dip systems. Insulating ROCKLATH is manufactured with a sheet of bright aluminum foil laminated to the back of plain Rocklath. It pro vides insulation against heat and cold and is an effective vapor barrier. ADVANTAGES All those oi plain Rocklath plus: 1. Insulating value equal to H in. fiber insulation board when installed with at least inch air space next to foil. 2. Aluminum foil is one of the best vapor barriers known and used com mercially. 3. Economical--one material, one application provides plaster base, insulation, vapor barrier. LIMITATIONS OF USE Same as plain Rocklath plaster base. Use only on the interior of exterior walls and top door ceilings. IMPORTANT When Insulating Rocklath is in stalled with at least a in. air space next to the foil, it has the same insulating value as a half inch of fiber insulating board. An efficient vapor barrier should be installed in all exterior walls and ceilings where freezing weather oc curs for extended periods of time. The vapor barrier should be located CD on the warm side of the exterior wall o or top floor ceiling. JUT O O Q* 4 11 e g o n C E U IN G S -s 32 :% - *2 3S - * ** * ^0 s _. 0*5 "> 0 -ao ^ 8* * 3) ai io O jo T5 "2 i".o27 I: * 1 I ^ c )c & o* s* ~ -- - ?o *11 o -- o* & a"* -2 woO * -4e" i1-se -S- ..l.Aa-^>.c9 o : o*- ' c Si 8* lit ^I l2w "0 *29 ' S " 5 25 uO n e 3 -3 5o =0 4 n 1 |o o a * (J ---- -- oo >1 13 r f' 1 -" -- ......... -- " ii* Plaster Base Typo*-- Rtommndd Stud Spacing--Special Umi IkiiiiimaM Stvd Spacing for ftiicknMi indicated. Ploin H', Vi* thick t 6* x 48' 16' o.c. 24' o.c. Vi* ROCKLaTH it particularly adaptable to nailable steel framing spaced 24* o.c. Perforated" Vx* thick 1 6# * 48' 16' o.c. 16' o.c. Required for higher Are rating Insulating Pfoin Long Length V-edge H', Vi* thick 16'* 48' 1 6' o.c. 24' o.c. Recommended for side wails and top floor ceilings for insulation and as a vapor barrier. A' thick 24' wide by ceiling height up to 12' For constructing 2' Solid ROCXLATH and plaster partftioni. (See page 65.) L A * W * rj Insulating Long length Square Edge %' thick 24' wide by ceiling heights up to 12'. For application to exterior masonry walls using USG Wall Fumng Brackett and Va* channels. (See page 68.) `C "Perforated ROCKLATH if not recommended for ceding oppdcatfonj when side* suspension clip attachments are i/ied. ts 05 o- CJ o o 4 14 M Sidowall and Coiling Application Apply 1 6 x 48 in. ROCKLATH with staggorad ond jointi on studs or joists, spaced 16 in, o.c. Apply 4 nails par board par support--space approximately 5 in, apart, H in. from edgos and ends. FIO. 2. Alternate Colling Application (Canadian system) 15 rr Long Length ROCKLATH plaster base Y< in. thick, 24 in. wide with V edges is used to construct 2 in. Solid Rocklath and plaster partitions. (See page 65.) Long Length Insulating Rocklath. Y% in. thick, is used as an economical tur ring application for exterior masonry- walls, providing ease of erection, insulation and an excellent vapor barrier (See page 63). ADVANTAGES The same fire protection as other Rocklath plaster bases of corre sponding thickness, as well as econ omy and ease of application. of ROCKLATH Proper Nails--Fortin. Rocklath, Sidewall and Ceiling Application-- nails should be 1Y in-, '3 gauge Rocklath plaster base should al blued, l?6 in. dat head, smooth dia ways be applied face out with the mond point. For Y in. lath, use ljy long dimensions at nght angles to in. length. For nailable steel fram the framing members. On walls, end ing (spaced not more than 24 in. joints should fall on different sup o.c.) use nails of proper gauge with ports in adjacent courses. On ceil not less than Y% in. heads and long ings, end joints are staggered as for enough to develop the proper nail side walls (See Fig. /) or Rocklath holding of the framing. should be erected so that end joints II are made continuous on a support, Nailing (Sidewalls and ceilings)-- in which case, end joints must be > Space nails approximately % in. covered with 1 in. stnplaih and the from the edges and ends, approx long or edge joint offset or staggered imately 5 in. apart, using four nails (See Fig. '). In all cases, Rocklath per lath per support. For Yi in. joints should be butted together. Rocklath with supports more than 16 in. o.c., nails must be spaced ap Cornarita and Cornar Baad Appli proximately 4 in. apart usmg 5 nails cation--Inside corners should be re per lath per support. For a one hour inforced over Rocklath plaster base ceiling tire rating when using sand as with comerite. Staple comente to the aggregate, 5 nails per lath per the lath to retain position until support plus striplath on joints must plastered. Comer bead should be be used. stapled to exterior comers. BB013 0074 ' 16 * PYROBAR and Other Masonry Plaster Bases PYROBAR Gypsum Partition Tito--A precast gypsum tile tor building non-load bearing fireproof partitions, either in new construction or alteration work. Because it is made of gypsum, it has a strong natural bond with gypsum basecoat plaster. Pyrobar is avail able in several types and thicknesses (See chart, page 19). ADVANTAGES Fireproof--3 in. hollow Pyrobar plastered two sides has 3 hour fire rating. 4 in. hollow Pyrobar plas tered two sides has 4 hour fire rating. Lightweight--30 to 50% lighter than other commonly used masonry units. Plattor Bond--safety factor of 173. Saves Plaster--large size, machine moulded units lay accurately to form a level surface, requiring less plaster as compared with other masonry units. Sound Resistant--3 inch hollow Pyrobar plastered two sides has a sound transmission loss rating of 39.2 decibels. 4 inch hollow Pyrobar plastered two sides has a rating of 42.8 decibels. Ratings in excess of 50 decibels are obtainable with resilient lath and plaster facings on one side of Pyrobar tile, normal plastering on the opposite side. Economical--low material cost . . . goes up fast . . . fewer joints, saves up to 20% of plaster and up to 40% of mortar ... easy to cut, less waste. LIMITATIONS OF USE 1. Do not use Pyrobar for loadbearing construction. 2. Portland cement and lime mor tars do not bond adequately with Pyrobar. Use Red Top Partition Tile Cement. 3. Do not use Portland cement or lime plasters over Pyrobar. Use Red Top Cement Plaster. Before applying Portland cement bedding for ceramic tile, nail or staple metal lath to Pyrobar. Other types of masonry, such as structural clay tile also may be used as backing for ceramic tile. 4. Where concrete floor fill, grano lithic finish, terrazzo or other wet types of flooring or base materials ^ are to be applied to the rough floor tB construction subsequent to installa- tion of Pyrobar tile, a continuous CJ coating of asphaltic material shall q be applied from rough floor up to O height of wet application on tile. ^ 17 umou nu uMm nukiinkmkio otmum unm ANOU OK CHANNIL UNTIL DIRECTIONS FOR ERECTING Mortar Requirements: use RED TOP Partition Tile Cement. Mix 1 part cement with 3 parts sand by weight. Mortar must not be retempered. Eroction: after door bucks are erected and rough plumbing and wiring are in place, lay the first course, with core holes horizontally, by bedding in mortar to a true and straight line. Lay succeeding courses in approxi mately y2 in. thick mortar beds, uni formly level in each course, and with vertical joints staggered. Cut all joints flush. Anchor partitions to intersecting masonry walls 12J^ in. o. c. vertically, with corrugated wall ties or 16d or 20d cut nails in mortar joints. Wedge tightly at ceiling and slush all chinks and crevices full with mortar. 18 Anchor wood door bucks to the Pyrobar with 16d cut nails or three buck ties each side (approximately 12 in. from top and bottom and at center) laid in the mortar joints. Lin tel construction (See above) should be held about Y% in. above head of wood buck and not siushed with mortar. Anchor steel door frames with proper ties, minimum of three each side (approximately 12 in. from top and bottom and at center), in mortar joints and slush space between tile and hollow frame with mortar. APPLICATION OF BASECOAT PIASTER Apply Rxd Top Cement Plaster mixed with 3 parts of sand by weight or 3 cu. it. lightweight aggregate per 100 lbs. plaster to yi" grounds. (See 33) BB013 0076 Other Masonry Bases Clay Tila and Brick--materials pro duced by exposing a clay putty to extreme heat until hardening, has taken place. Clay tile is produced in 12 x 12 in. size in thicknesses usually 2 to 6 in. with scored faces. Concrete Block--precast in molds using a slurry composed of cemen titious materials and an aggregate. It is generally produced in 8 x 16 in. size in thicknesses usually 3 to 12 in. and must have rough, porous faces. Such units must be properly cured to minimize volume changes during and subsequent to plastering. These masonry plaster bases are available in units for constructing interior bearing and non-loadbearing partitions and should be used as a backup for ceramic tile, terrazzo and cement bases. Portland cementlime sand mortar is generally used for laying up, although Red Top Partition Tile Cement can be used where construction will not be ex posed to undue wetting. They are 60-80*'^ heavier in weight than Pykobar Partition Tile, and thickness for thickness, have a lower fire resistance rating. Gypsum plaster may be applied di rect to these units providing the surface is porous to develop proper suction or scored to develop ade quate mechanical bond with plaster. Monolithic Concrete--many multi ple story fireproof buildings are constructed of poured reinforced concrete. Frequently, specifications require application of plaster basecoats direct to the concrete. It is important, in order to secure proper bond between the concrete and gypsum plaster, that specifica tions for this particular application be strictly adhered to. {See page jg). PYROBAR Partition Tile Data Sire of-PYROBAR Partition-Tile- Limiting? . Partition. ' Height- ApproximateWeight par? sq.fh.Tile- Partition- Tile? Cement Required/ '-parMsq. ft. Tile 2x12x30 in. solid 3x12x30 in. hollow 4x12x30 in. hollow 6x12x30 in. hollow 10 ft. 13 ft. 17 ft. 30 ft. 10 lbs. 10 lbs. 13 lbs. 20 lbs. 500 lbs. 700 lbs. 900 lbs. 1300 lbs. BB013 0077 19 MEMORANDUM B B 0 i3 0070 USG COLOR-RITE METAL LATH USG Color-Rite Metal Lath is rustresisting copper alloy sheet steel, slit and expanded to form a multitude of small mesh openings. It is further protected by dipping the expanded sheet into black asphaltum paint. (Exception: 3.4 lb. diamond mesh when made from galvanized sheets.) ADVANTAGES OF USG COLOR-RITE METAL LATH 1. Strength and Rainforcing -- Metal lath embedded within the plas ter provides strength in a manner similar to steel reinforcement in con crete slabs, thus providing high resistance to transverse impact. It decreases the hazards of serious cracks and failures due to structural movement of the frame. 2. FlaaiWa-- Readily shaped to or namental contours to a degree not possible with other plaster bases. 3. Quality Plastaring--It makes the use of over-aggregated plaster m the scratch coat impractical. 4. Economy--Intended for highest quality, Ere resistant, durable plas tering with low maintenance costs. 5. Firo Rasistanco--Metal lath and gypsum piaster provide high Ere ratings. USG COLOR MARKING SYSTEM USG Color-Rite Metal Lath is the newest development in the metal lath industry. Ends of bundles are spray painted red for all 3.4 lb. lath, mMite for 2.5 lb. diamond mesh and 2.75 lb. riblath, yeiUrus for 4.0 lb. J'j' riblath. This makes warehousing, inventory and job distribution easier and positive. An architect may quickly and visually inspect a job to make sure the weight lath he speci fied is used. When the lather erects the colored end to the right as we recommend, the plasterer saves up to 25 nercent of the scratch coat; saves time and effort because of the uniform "drag" on his trowel since all sheets lay in the same direction. N eioaa USG COLOR-RITE Diamond Mesh Lath Size: 27 in. x 96 in. A amail m**h (approximately 11,000 per yard) diamond pattern mere) plattoring base. A peneraJ all pwrpeea lath. Beat far ernamental, centaur platlerinp. The small meehee conserve piaster and reduce droppinps. Weights: 2.5 lbs. (End Painted White) and 3.4 lbs. (End Painted Red) per square yard. Galvanized available in 3.4 lb. weight only. Limitations of Use -- Specify "self-furring" for use as stucco base and 3.4 lb. galvanized where additional corrosion resistance is required. Also an ideal plaster base for lathing over old plaster surfaces. USG COLOR-RITE 1/8 in. Riblath (Fiat Riblath) Six*: 24 in. x 96 in. A KwriAgb.il, math pattern, with '/ in. 4en* Z-hap4 rtha running len*rhwtee at tha ahaat at 1'/: in. imanual.. Stiffening ribs and herringbone pattern increase rigidity, thus per mitting a wider spacing of sup ports or a saving in the weight of lath required. Particularly suitable for attachment by nailing. Small meshes conserve plaster materials. Weights: 2.75 lbs. (End Painted White) and 3.4 lbs. (End Painted Red) per square yard. Limitations of Us*--Its rigidity makes it unsuitable for contour lathing. Use Diamond Mesh. B B 013 OO0O 22 USG COLOR-RITE 3/8 in. Riblath Size: 27 in. x 96 in. A herringbone pattern mesh with H in. deep V-sheped ribs running ImfHiwiM of the sheet of 4'/t in. intervals, with invert ed intermediate Me in. riba. The heavy riba provide exceptional rigidify. Uaad whan support* are apaced mare than 16 in. e.. and not more than 24 in. o.c. and for 2 inch aoiid (atudleaa) portitiona. Desirable os a piaster baee for heavy duty plastering. Used as centering and reinforcement for concrete fleer and reef slabs. Weights: 3.4 lbs. (End Painted Red) and 4.0 lbs. (End Painted Yellow) per yard. Limitations of Use--Its extreme rigidity makes Vi in. Rib-lath un suitable for contour lathing. Use Diamond Mesh Lath. USG COLOR-RITE 4-Mesh Z-Riblath Six*: 27 in. x 96 in. A "flat nb" hype of loth with smaller mesh openings. An excellent nail-on lath, or for tie-en werfc an flat ceilings. Weights: 2.75 lbs. (End Painted White) and 3.4 lbs. (End Painted Red) per square yard. Limitations of Use--Use Dia mond Mesh lath for contour plas- tering. * oCO k. Q O ' 23. p STRUCTURAL AND TRIM ACCESSORIES USG offers a complete line of ac cessories. A11 beads, base screeds and picture mould made from 26 gauge galvanized steel. 1-A Expanded Corner Bead--Its wide expanded flanges are easily flexed. Preferred for irregular cor ners. Provides increased reinforce ment close to nose of bead. 4- A Flexible Corner Bead--The general purpose corner bead. Eco nomical and most generally used. By snipping flanges, this bead may be bent to any curved design (for arch ways, telephone niches, etc.). 5- A Bull Note Corner Bead --A % in- fadius bull nose bead with short flange. Used for rounded cor ners. Can be secured to corners with No. 9-A Comer Bead Clips attached to flanges, where wide nailing flanges are required. 10-A Expanded Bull Nate Corner Bead--A bull nose bead similar to above, but with in. wide ex panded flanges. Especially suitable on corners where plaster base is uneven. 3-A Expanded Flange Bate Screed-- A flush type H in. ground (job shimmed to Jt* inch grounds) with wide flexible -expanded flanges for added reinforcement or tor attach ment to uneven surfaces. Used as a dividing point between plastered sur faces and Portland cement base. 6- A Plain Bata Scroad--.A flush type Vl in- ground (job shimmed for H in. grounds), used at the juncture of different nnishes. 7-A Curved Point Bate Sc rood-- For use where base or wainscot is to project beyond the plastered surface. Made for Yi in. piaster ground (job shimmed for in. grounds) with H in. projection for base or wainscot. 24 BB013 00B2 B-A Picture Mould--A concealed mould. Attached to lath and plas tered flush to the slotted opening. Grounds H in. (job shimmed for % in. grounds). USG 2 in. Partition Terminal--For use as a vertical partition terminal for 2 inch solid metal lath or Rocxlath partitions, or as a runner where 2 inch partitions abut an unplastered suriace. Cap is of 18 gauge steel weldedtoa 24 gaugepunched runner. Standard length 8'-2". Prime coated. Lathing Channels--Strong, light weight cold rolled channel sections used for furring, suspended ceilings, partitions,etc.Sizes: % in.or 1 Yi in., 16 ft. or 20 ft. lengths. Weights: ?<; in. 300 lbs. per M Lin. Ft., 1}4 in., 314 lbs. per M Lin. Ft. Made of 16 gaugesteel, black asphaltum painted. USG Selv-Edgo Cornerite and Striploth--Cornerite is a 4 in. or 6 in. wide strip of 2.5 lb. copper alloy painted diamond mesh lath, bent to form a 100 angle, length 96 in. Striplath is a 4 in. or 6 in. wide strip of 2.5 lb. diamond mesh lath, copper alloy, painted, 96 in. long. Metal Door and Window Casing Beads-- Used as a plaster stop and ground at window and door open ings, eliminating wood trim. No. Type Flange 4 quarter round xpanded 138 quarter round short 60 semi square short or oxp. 66 square short or oxp. .All expanded flange casings avail- CO able in and grounds; short flange in J^', and Vh grounds. 2 .All casings manufactured from 24 CJ gauge galvanized steel and furnished Q in 7', 8' and 10' lengths. p 25 APPLICATION of METAL LATH IMPORTANT Observe the minimum weights of lath for spacing of supports listed in table below. Use only dean sand, perlite or vermiculite for plastering. Do not use unwashed salt water sand. When humidity is higher than nor mal and moisture or acid fumes are anticipated, contact your nearest USG Sales Office for proper recom mendations. How to Erect COLOR-RITE METAL LATH 1. Lath ceilings first with sheets carried down six inches on to the walls and partitions. If metal lath is not used on the ceiling, then carry out metal lath six inches from the walls onto the ceiling plaster base. 2. Apply metal lath with long di mension of the sheet running across the studs, joists or furring channels. Secure sheets by nailing along studs or joists or tieing to channels at not more than six inch intervals. 3. On sidewalls, begin lathing at top and continue downward. Place sheets so that the lower sheet laps over the upper sheet. Diamond mesh USG METAL LATH TECHNICAL DATA TYPES AND WEIGHTS OF METAL LATH AND SPACING OF SUPPORTS TypttolLdlktr '' Diamond Mesh Diamond Mesh Diamond Mesh V Z-RIb Z-Rlb %' Rib H' Rib . Weight-Per- Square Yank 2.5 lb. 3.4 lb. 3.4 lb. 2.75 lb. 3.4 lb. 3.4 lb. 4.0 lb. Typmaf Steal Copper Alloy (l) Copper Alloy Galvanized (2) Copper Alloy Copper Alloy Copper Alloy Copper Alloy STUCCOMESH (31 STUCCOMESH 1.8 lb. 3.6 lb. Copper Alloy Copper Alloy Nalae ( 0 Copper o/loy tofft coirtoint bom 0.2% to 0.25% pare copper. (2) Gafvsnind Jetfi it art from galvanized dteefr. (3) STUCCOMESH goorally applied over oxtonor timathing. 09 08 o u oo a lath is carried around comers at least one stud spacing. 4. Riblath on both sidewalis and ceilings is applied with ribs against the supports. 5. Lap diamond mesh at sides not less than }A in. and at ends not less than 1 in. Riblath is lapped at sides by nesting outside ribs, and at ends by lapping not less than 1 in. 6. Tie all side laps with 18 gauge tie wire at least midway between joist or stud supports, but at not more than 9 in. intervals. 7. Ends of sheets generally should occur over supports; if between, ends of sheets must be securely laced together with 18 gauge tie wire. 8. Staggering of sheets is preferred, but not essential. How to Nail COLOR-RITE METAL LATH DIAMOND MESH and FIAT RIBLATH On walls--4d common nails driven % in. and bent to engage three strands, or 1 in. Mi in. head roonng nails, or 1 in. No. 14 wire staples. On callings--lj'j in. No. 11 gauge, Mt in. head barbed roonng nails. Y\ IN. RIBLATH On walls--4d common nails driven through the rib or 6d common nails driven z/i in. and bent over the rib. On catlings-- 1^ in. No. 11 gauge SizeSheet*'- 27'x 96' 27' x 96' 27'x 96' 27'x 96' 27' x 96' 27* x 96' 27* x 96' 41**99* 4Sr x 99* Wood- 16' 16' 16' 16' 19' 24' 24' U'(3) 16'(3) Maximum Allowable Spacing* Vortical Support* Harisanfal Support* Mata I . Solid; Partition* Other** (5) W*6roc Concrete*' Metal 16' 16' 16' 16' 24' 24' 24' 12' 16' 16' 16' 19* 24' 24' (41 16' 16' 16' 19' 24' 24' (41 13'/i' 13W' 12' 19' 24' 24' B B 0I3 0003 All motal lath (except galvanized) I* painted with a rusMnhibitlve black asphaHvm paint. MJ Not recommended, txcopt for firoproofing of ttooi thopog. (SI Including rorhcol furring. 27 ri r- 14 in- bead barbed roofing nail driven through the rib. Lathing nails--for 16 in. stud spacing, nailing 6 in. o.c. requires approximately 17 nails per sq. yd. Tie-Up Work For tying metal lath to channels use 18 gauge galvanized annealed tie wire. For tying channels to channels (horizontal or vertical construction) use 4 strands of 18 gauge or 2 strands of 16 gauge galvanized an nealed tie wire. Estimating Quantities For Sutpondod Calling*--The fol lowing "rule of thumb" method will be found helpful in making a quick approximate quantity estimate. 1. Determine surface area in square feet. Example: ceiling area 30 x 100 feet = 3,000 square feet. Divide by 9 to determine square yards of metal lath required. Assume standard suspended ceiling construction of 1 Vi in. runner chan nels 3 feet apart, and in. furring channels either 12 in. or 16 in. apart, depending on type and weight of metal lath used. 2. Quantity of l!-< in. channels 3 feet apart--divide square foot area by 31^ (3,000 divided by 2i'-o= 1200 lineal feet). 3. Quantity of z,i in. channels 12 in. apart--multiply square foot area by 1.1. (3,000 x 1.1 = 3.300 lineal feet.) 4. Quantity of z/i in. channels 16 in. apart--multiply square toot area by 0.8. (3,000x0.8 = 2,400 lineal feet.) 5. Figure tie wire at approximately 10 pounds per 100 square yards of lathing. Nail Data lortd Roofing Noils (Hs in. hood) Common Nods / 28 Iwilh1 iru 1 ifU- id 6d. Gang* Now 1 1 No. 1 1 No. I2'/z Now 11 Vi Not ptr1 27S 188 316 181 Ed IoS u o 3 0" SIZE AND SPACING OF HANGERS FOR SUSPENDED CEILINGS six. Trp* Maximum Coiling Aroa Maximum Contor to Contor Supportod par Hangor Spacing of Hanqoro No.9GowgoGoivonisod Wiro I2Vi sq: ft. No. SGowqoGolvanizod Wlro 16 tq. ft. Ms' Mild Stool Rod (U (21 Mild SI..I Rod (1) (2) ) > 23 iq. ft. ?Vx Ir Mild SI..I flat (11(21) 4 ft. X 3 ft.; 3!A ft. X 3'A ft. 4 ft. X 4 ft.; 3 ft. X 3 ft. 6 ft. x 4 ft.;7 ft. x 3 'A ft.; 8 ft. x 3 ft. (1) Golvanizsd rods and rviit inhibitivo painted or golvanizod strops rocommondod whtr tovcro moisturo conditions may occur. (2) Not manufocturod or mppJiod by Unitod Stotos Gypsum Company. SIZE AND SPACING OF MAIN RUNNERS Slso A Typo Woight por 1000 Unoal Foot Maximum Spacing of Hangors along Runnors Contor to Contor Spacing of Runnors 1 'A' Cold Roflod Oramwl 314 Ibm. 1 Vi* Hot ftollod Chonnoi (2) 1120 Ibt. 2' Cold Roll.d OommI 623 Ibi. 2' Hat Roll.d Oia/vwl (2} 1260 Ibi. 3'A' Hat Rollwf Oiontwl (2) 1300 Ibi. 2 Vi * Hot Roilod Otonnol (2) 2270 Ibt. 4 ft. 3 ft. 3 H. 6 ft. 7 ft. 8 ft. Up to 4 ft. Up to 4 ft. Up to 4 ft. Up to 4 ft. Up to 3'A ft. Up to 3 ft. 2) Not manufaourod or supplied by Unitod Stotos Gypsum Company. STEEL STUD PARTITIONS (PER 100 SO. YDS.--ANY CEILING HEIGHT) Unooi Foot of Coiling or Floor XsHROf Roquirod With Spacing of Stodo Approximoto Unoal Foot of Studo R squired 900 + coding hotghf 12 in. Sams 16 in. Somo 19 in. Soma 24 in* Loth on# sido-- 1 00 sq. yds. roquirod. Loth two sidos--200 sq. yds. roquirod. 910 lln. ft. 673 lln. ft. 370 lln. ft. 433 lln. ft. B B 0 I3 0087 29 MEMORANDUM bboi3 ooea Basecoat Plasters RED TOP Gypsum Basocoot Plasters Aggregates Mixing -- Application Important Job Precautions RED TOP Cement Plaster RED TOP STRUCTO-LITE Plaster RED TOP BONDCRETE Plaster RED TOP Wood Fiber Plaster Portland Cement Plasters PAGE 32 38 38 39 39 41 BB013 00B9 Basecoat piasters are applied to bases of masonry or lath and support the finish coat. Their primary functions are to cover the base, receive the finish coat, and tie together all units into a durable continuous slab. Of the three general types of basecoat plasters, gypsum plas ter is by far the most modern and widely used. Portland cement piaster excels for a few specialized uses, while lime plasters-- very limited in use--have been largely replaced by gypsum and Portland cement. 31 RED IOP Gypsum Basecoat Plasters ADVANTAGES Uniform--setting time is stabilized. Hazards due to job conditions and variables in water and aggregates are minimized. Controlled set as sures maximum hardness and high strength. Firoproof--gypsum is incombusti ble, will not transmit high tempera tures until completely calcined. It actually fights fire by retarding spread of dame. Plastic--gypsum base coats are highly workable and easy to apply. Strong--capable of withstanding normal wear and abuse for the life time of the building. Adaptable--gypsum bonds firmly to any approved plaster base and will take most any type of finish coat. Economical--high coverage with minimum effort. Easily worked and mixed. GENERAL LIMITATIONS OF USE 1. Aggregate must be added strictly according to specifications. Use of too much aggregate reduces the strength of the plaster slab. 2. Red Top Cement, STRUCTOLITE or Wood Fiber Plasters should never be applied to concrete. Use Bondcrete as required according to directions. 3. Res Top Plasters should not be used on exteriors exposed to the ele ments, or on interiors where exces sive water or moisture is expected. Use Portland cement-lime plaster. 4. Bituminous compounds do not provide a good base for gypsum plaster basecoats. Therefore, do not apply such plasters to masonry walls and concrete that have been treated with these compounds. 5. Because of possible moisture con densation or water seepage, direct plastering to the inside of exterior masonry walls is not recommended. Such walls should be furred prior to plastering. 6. When used in conjunction with Radiant Heating systems, the tem perature at the surface of plaster shall not exceed 115 F, nor shall water in the pipes embedded in the plaster exceed 125 F. Gvpsum-sand plaster has approximately three times the conductivity of gypsumlightweight aggregate plasters. Aggregates Aggregates in the form of sand--and more recently, perlite and vermiculite--are added to gypsum cement plasters to extend coverage and re duce cost. They also act as a gauging agent to minimize shrinking of gyp sum in setting. The proper use and proportioning of aggregates with gypsum plaster determine the ultimate strength and 32 BB013 0090 hardness of a plastered wall. Typical compressive and tensile strengths that result with use of sand and lightweight aggregates (perlite, vermiculite) in varying plaster mixes are shown in the chart on following page. The American Society for Testing Mate rials in ASTM Designation C35-54T has established the following specifications as standard for the proper gradation of good plastering aggregate: si#v sis* 4NO. . . 8No. ... . No. Id... 30No. ... 30No. . 100No. .. on Inch Poriito, by voJ* wmo viit* by woiwmo Mom Mi* Ma Min 14980333003 478133860 0 17990T3830O 467933600 Sond. by wo*b Mti Min 69335030 TOO 63950063 SAND Sand Is the most commonly used plaster aggregate because it is eco nomical and widely available. Proper proportioning and gradation of sand are most important in determining built and working qualities of plaster, and the ultimate quality of the fin ished wall. Over-sanding or the use of an excessive amount of fine sand reduces the strength and hardness of gypsum plasters. VERMICUllTE is mined as a mica rock, ground and expanded under heat into lightweight granules for use as a plaster aggre gate. It should weigh between lbs. and 10 lbs. per cubic foot and comply in gradation with ASTM designation C35-54T Inorganic Ag gregate for use in Interior Plaster. Walls plastered with gypsum plas- Recommended Proportioning & Coverage Gypsum Comont Ploitsr (weight) Gypsum Comont Plaster (100 lbs.) Sand (woight) or Porllte or Vormicullte (cu. ft.) Plaster Basa Gypsum Lath Motel lath Unit Masonry Two Coat Work Scrotch-Doublo Bock h2'/i -- 1:3 Three Coat Work Scratch coat Brown Coat 1:2 i a 1.3 1:3 Coverage Range Sq. Yds. Per Ton- 175-220 90-125 175-200 B B 0I3 0071 33 Relative Strength of Various Plaster Mixes Mix Comprestive Strength lb*. per sq. inch Weed Fiber Neat Cement Ploeter Plaster to Send by Weight 1:1 1:2 1:3 CiimiiI Floitir Vermiculite por 100 if Cimtnf ftailir 2 cu. ft. 3 cu. ft. Cement Plaster Partita par 00 4 Camant Piaster 2 cu. ft. 3 cu. ft. 2100 1900 1200 750 500 300 1000 650 Tensile Strength lb*. par vq. inch 100 215 170 120 130 90 165 105 Whin tha proper amount of aggregate ho* been u*ed, each grain of aggregate is cemented on all sides to its neighbors by the gypsum. When the proportion of aggregate to piaster is escetsiee, the aggregate is not properly cemented. See illustrations below. ter containing vermiculite as an ag gregate have lower strength and re quire a longer period for drying than walls of sanded plaster, but are lighter in weight and have greater fire resistance. Where hard finish coats (Keenes cement) are to be used, reduce the proportion of vermiculite to gypsum plaster in the basecoat. Vermiculite is proportioned with gypsum plaster on a volume of aggregate to weight of plaster basis, and the proportion ing should be in strict compliance with the table on Page 33. PERLITE Perlite is a lightweight plaster ag gregate produced from a volcanic rock. The perlite ore is ground and screened to proper size, then ex panded to produce a light grey or white colored aggregate. Perlite ag- PROPER AMOUNT OP AGGREGATE EXCESSIVE AGGREGATE 1BB013 0 0 9 2 gregate for plastering should weigh between 7J4 and 15 lbs. per cubic foot. It should meet ASTM C35-54T Inorganic Aggregate for use in In terior Plaster. It has excellent fireresisting qualities and when mixed with gypsum plaster it provides a higher strength plastered wall than does vermiculite. (See comparative strengths of various basecoat plas ters, page J4-) Perlite is added to gypsum plaster on a volume of perlite to weight of plaster and should be proportioned in strict accordance with specifica tions. Not*: See limitations, pages 32 and 37, if perlite or vermiculite aggregate is to be used with plaster on radiant heating jobs. WATER All gypsum plasters require the addi tion of water on the job. Water pro vides lubrication and workability to permit application to the plaster base. It also induces the proper set ting of gypsum. As a general rule, any water fit to drink is suitable for mixing with plaster. MIXING Gypsum basecoat plasters may be machine or hand mixed. The former is preferred because it disperses the plaster, the aggregate and the water more evenly. Machine Mixing--place the required water in the mixer. Add approxi mately half the required aggregate. Add all the plaster. Add the balance of the aggregate. If necessary add more water to obtain the proper con sistency. Mix not less than 1 minute or more than 3, depending on the speed of the mixer. Dump the entire batch at once. Clean the mixer thor oughly when not in use or continuous operation. Box Mixing--dry mix plaster and aggregate together until completely blended. Add water, and hoe plaster into the water until thoroughly mixed to proper consistency. PLASTER GROUNDS AND THICKNESS To attain proper wall strength it is essential that the plaster slab be applied to the proper thickness. This is controlled by the use of grounds. Grounds should be set to provide a minimum plaster thickness of: (a) inch over gypsum lath; (b) pi inch over gypsum partition tile, brick, clay tile or other masonry, (c) % inch over metal lath when measured from the back of the lath (pi inch from face of the lath). BB013 0093 35 APPLICATION of RED TOP PLASTERS Plastering specifications may require either two-coat or three-coat work. Two-Coat Work consists of one base coat and one finish coat. It is gen erally used over a masonry plaster base and often over gypsum lath. The basecoat plaster is applied in one coat by either the "single-foot" or the "scratch-double-back" method to slightly less than the thickness of the grounds. It is rodded and darbied to a true, even surface left rough enough to take the finish coat. Throo-Coot Work consists of a scratch coat, a brown coat and a finish coat. Three coats are required over fiber insulating or metal lath. The first or "scratch" coat properly aggregated is applied to a thickness of approximately Y inch over the face of the lath and then cross-rakcd before it sets. This provides a me chanical key for the brown coat. The brown coat is then applied directly to the set scratch coat. The brown coat is used to fill out to just slightly below the grounds and is rodded and darbied to a true, even surface. It is left rough enough to properly receive the finish coat. IMPORTANT JOB PRECAUTIONS 1. Equipment and Storage of Ma larial!-- All successful plaster jobs require adequate equipment (mortar boxes, mortar boards, scafiolding and tools). Every job should be properly planned to provide ample scaffolding to permit continuous application of both basecoat and finish plasters for a complete panel of either a wall or ceiling. Keep all mixing tools clean. Wash them in clear water only. Keep plaster stored in a dry location. Stack on planks raised off the ground and away from damp wails or doors. 2. Healing--Plaster must not be applied to surfaces that contain frost. A minimum temperature of 55 F. should be maintained in the building for an adequate period prior to, dur ing and after the application of the plaster. In cold, damp or rainy weather, properly regulated heat should be provided, but precautions must be taken against too rapid drying before set has occurred. This avoids "dry outs." 3. Ventilation--As soon as the plas ter has set, free circulation of air should be provided to avoid "sweat outs." After piaster has set, heating should be continued to insure as rapid drying as possible. In hoc, dry weather, protect the plaster from wind, and from drying unevenly or too rapidly before set has taken place. If glazed sash are not in posi tion, exterior openings in the build ing should be screened with cheese cloth or similar material. 4. Finishing Over lightweight Aggregate Basecoat]--The use of lightweight aggregates (.perlite and vermiculite) with gypsum basecoat plasters often results in a basecoat BB013 36 % having a high suction (because ot higher porosity). In applying a dnish coat over this high suction base, the water in the finish coat is quickly sucked into the thirsty basecoat making application of finish difficult, due to loss of easy working charac teristics of the finish plaster. Furthermore the finish coat is sometimes susceptible to severe check cracking, because water is sucked out before gauging plaster is set--thereby nulli fying purpose of the gauging plaster (provide initial set to avoid possible shrinkage of the lime-putty finish). Necessary precautions should be taken to apply finish coat plaster before the basecoat becomes thor oughly dry. When a basecoat has become bone dry, before finishing, spray lightly with water to eliminate the excessive suction of the basecoat, then apply finish coat. 5. Radiant Hoating--The Gypsum .Association makes the following rec ommendations when radiant heat ing coils are specified for use in a ceiling or are to be embedded in the plaster slab. a. In all radiant panel heating sys tems where gypsum plaster or gyp sum products are concerned, the surface temperature shall not exceed US degrees F. In those systems where pipes are embedded in gypsum piaster, this shall be met by requir ing the water temperature in the pipes in contact with the plaster not to exceed 125 degrees F. {Note: The 12SF maximum water temperature is 15`F below that rec ommended in the A.SBACE Guide to avoid possibility of calcination of the gypsum.) b. Radiant heating coils should not be used to heat the building or dry the plaster slab in which they are imbedded. The heating system should only be turned on and brought up to operating temperatures very slowly after the plaster slab is thoroughly dry. e. Where heating elements are em bedded in gypsum piaster, a mini mum cover of Y% shall be maintained over the coils. d. In radiant panel heating systems where the pipes are to be embedded in plaster applied to metal lath or gypsum lath, these pipes shall be supported by the framing and not by the lath. . Gypsum plaster, when used with radiant panel heating systems, shall be mixed and applied in accordance with the ASA A42.1 "Standard Spec ifications for Gypsum Plastering." The design of a radiant panel heat ing system is the responsibility of a heating engineer, and the lathing and plastering specifications must be established by the designer. There fore, lightweight aggregates (vermicuiite and periite) or mill mixed plasters incorporating them (Structolite), should not be used unless the heating engineer, heating contractor or architect have designed the heat ing system for their use, as light weight aggregates offer greater re sistance to the flow of heat than plasters mixed with sand. BB013 0099 37 RED TOP Cement Plaster This is a ``neat" gypsum plaster which requires the addition of an aggregate (sand, vermiculite, per lite) and water on the job. It is the most common base coat plaster be cause job-addition ot aggregate gen erally provides low cost. It is used for both scratch and brown coat work, and for application over all approved plaster bases. The use of fiber in plaster stems from its use with lime base coat plasters years ago. Lime does not set and requires a long period of time to harden. Consequently fiber was ne cessary to add cohesiveness to the mass. ADVANTAGES Red Top Cement Plaster is fireproof, adaptable, plastic, uniform and strong. It is perhaps the most eco nomical base coat plaster in use today. LIMITATIONS see general limitations noted on page 32. Job-addition of aggregates must be in strict accord with gradation and proportioning specifications. Red Top Cement Plaster is avail able in two types: Regular for sand aggregate and LW Formula for light weight aggregate--both types avail able for machine application or hand application. For hand application both types are available "fibered" or "unnbered." It is usually desirable to use fibered plaster for scratch coat work on metal lath. It helps hold plaster mortar to lath until set takes place. Unnbered plaster is suitable for use over all other bases. 38 RED TOP STRUCTO-LITE Plaster This is a mill-prepared base coat plaster using a properly graded and proportioned perlite aggregate. It is ready for use with the addition of water only on the job. tiRED TOP' STRUCT<MttT GYPSUM PIABTBI ft & a) ao) H* (J o o .a o* ADVANTAGES Controlled proportioning of a prop erly graded and sized perlite aggre gate. Weighs much less than plaster and sand aggregate. Less than half the weight on wall. More fireproof. Offers fire ratings almost double those attained with plaster and sand. Miil formulation reduces suction to that of plaster and sand, assures easy application of the finish coat. Job-mixed lightweight aggregates often create considerable suction for finish coat work. Stabilized set. LIMITATIONS See general limitations page 32. approximately 509c greater surface hardness; 50 to lOCvc greater fire rating than plasters containing sand. Highly desirable for use where good plastering sand is not available, and for alteration, patch and repair work. LIMITATIONS see general limitations page 32. Wop- 1 1 WOOD FIBER ( ***** RED TOP Wood Fiber Plaster This is a mill prepared base coat piaster containing a wood fiber ag gregate and requiring the addition of water only on the job. Over masonry surfaces, one part sand by weight may be added for easier work ing qualities, and to minimize shrink age cracks. ADVANTAGES Red Top Wood Fiber Plaster is rec ommended for use where excessive strength, toughness, or a higher fire rating is required. It has: three times the compressive and tensile strength of plaster sanded 1:3 (see page 34); RED TOP BONDCRETE Plaster This is a specially formulated gyp sum base coat plaster requiring only the addition of water on the job. It is the only recommended base coat plaster for application to properly prepared, rough monolithic concrete. ADVANTAGES unlike normal gypsum base coat plas- g ters, Bondcjlete has thermal expan- sion equal to concrete, which pro- vides continuous bond to this type U surface. g 0 39 >4 BONDCRETT gypsum PIASTB for concrete rSr 1 LIMITATIONS Bokdcxete should be used only on rough concrete that is properly pre pared for plastering. It should never be applied to smooth concrete. Maximum thickness of Bondcrxte and finish coat should not exceed Y% in. on ceilings, and s/$ in. on walls. If additional thickness is required, metal lath must be prop erly secured to the concrete surfaces before applying the plaster. Surface Preparation--monolithic concrete surfaces should be brushcleaned of all dust, loose particles and other foreign matter. Any laitance and efflorescence should be re moved by washing with a 10% solu tion of commercial muriatic acid and water. Grease or form oil should be removed by wiping with naphtha spirits. If surfaces are not rough enough to provide necessary mechanical key, they should be hacked or bushhammered; or a dash-coat of portland cement grout composed of 1 part of cement and 1 Yi parts of fine 40 sand (mixed to a mushy consistency) may be applied. Keep this coat damp for at least 2 days immediately fol lowing application and then allow to dry. Before application of BondCRETE, the surface should be evenly dampened to provide proper suction. Application ta Concrete Ceilings-- apply coat of Bosdcrzte Plaster, scratching in thoroughly, doubling back and filling out to true, even sur face left rough by brooming to receive the finish coat. Application to Walls and Columns --apply a scratch coat of Botrocrete. Follow with a brown coat of gypsum piaster (1 part Red Top Cement Plaster to not more than 3 parts of sand by weight) troweled into the scratch coat before it has set. Bring out to grounds and level to true, even surface using rod and darby. It is then ready to receive the finish coat. Total thickness of plaster should not exceed in. Portland Cement-Lime Base Coat Plaster Portland cement, with the addition of lime to provide working qualities and water resistance, is frequently mixed with sand and water to form a piaster mortar. It is chiedy used as a base coat for exterior stucco and in places subject to excessive moistr such as swimming pools, show. at dairies and steam rooms, and a back up material for ceramic tile CJ O o -0 CD LIMITATIONS Portland cement-lime base coat plas ter is comparatively unplastic and hard to apply, thus high in cost. It must be kept damp to properly cure and prevent drying out and cracking. Several days delay between coats is necessary to assure proper curing and hardening. Mixing and Application -- Mix scratch coat in the proportion of one bag of portland cement, two bags of Mortaseal or Red Top Masons Hydrated Lime (2 cu. ft. lime putty) and not more than IVi cu. ft. of sand (approximately 40 No. 2 shovels). For application over stucco mesh or self-furring metal lath, approximately two pounds of hair or fiber should be added to each mix. Mix brown coat in the proportion of one bag of portland cement, two bags Mortaseal or Red Top Masons Hydrated Lime (2 cu. ft. lime putty) and not more than 9 cu. ft. of sand, approximately 50 No. 2 shovels). Scratch coat should be applied in a full % in. thickness with sufficient pressure to form a good bond with masonry surface or to force it through and completely embed the stucco mesh or metal lath. Cross scratch, and after set, damp cure for not less than 48 hours. Brown coat should be applied over the dampened scratch coat to a full y% in. thickness with sufficient pres sure to form good bond. Rod the brown coat level, and broom the sur face to provide key for the finish coat. After set, damp cure at least 48 hours before applying the finish coat. (See Omental Exterior Stucco for finish coat, pa%e 49). Curing--damp cure each coat by applying water in a fine fog spray. Apply only as much water as is readily absorbed. The frequency of spraying depends on the weather, with more frequent applications re quired during hot, dry or windy weather. BB013 009? 41 MEMORANDUM 42 BB013 0100 Finishing Plasters Gypsum-lim Putty Trowel Finish Keene's Cement-lime Putty Gypsum Trowel Finish STRUCTO-GAUGE Lime Putty Gypsum Sand-Float Finish ORIENTAL Interior Finish ORIENTAL Exterior Finish SABINITE Acoustical Plaster USG HUITE Acoustical Plaster RED TOP AUDICOTE Acoustical Plaster PAGE 44 44 47 47 48 49 49 51 53 54 BB013 0101 Finish-coat plasters applied to basecoats (generally of gypsum plaster) provide the surface for final wall or ceiling decoration. They are either factory prepared, requiring the addition of water only; or they may be job-mixed by blending lime putty and gauging plaster, or Keene's Cement or Sxaocro-GACGE. Finish-coat plasters are normally applied to a thickness of inch for trowel finishes, up to inch for float finishes and 3^2 inch for acoustical plaster finishes. Finish-coat piasters are selected according to job requirements for texture, color, hardness, sound absorption and type of base coat. 43 USG Finishing Plasters Gypsum-Lime Putty Finishes Finish lime putty into which is blended a gypsum gauging piaster is commonly known as "white coat." It is the most widely used finish coat because of its good working qualities, whiteness, economy and ability to take any form of decoration. Usually it is troweled to a smooth hard sur face over a gypsum base coat. With the addition of sand, it is adaptable for sand-float finishes. FINISHING LIMES Made from specially selected lime stone rock of high purity, the most popular finishing limes come from the doiomitic fields in northwestern Ohio. They have excellent working qualities. There are three types of finishing limes: (1) double hydrate, (2) normal hydrate and (3) quick lime. Each requires specific handling in slaking or soaking to produce a good finish ing lime putty. Double Hydrate Finish Lime Usually made from Ohio doiomitic limestone. It is over 92% hydrated during manufacture which eliminates troubles from delayed hydration, ex pansion and separation in the wall. Upon mixing with water, double hy drate finish lime immediately devel ops high plasticity. Thus, overnight soaking is unnecessary. ADVANTAGES Can be mixed with water by hand or with mechanical mixer. Becomes highly plastic right away. Easy working; uniform; white. Eliminates troubles from delayed hydration. USG Brand--IVORY FINISHING LniE (Genoa, Ohio). Normal Hydrate Finish Lime generally made irom Ohio doiomitic limestone, it is the most widely used today. Although hydrated in manu facture, overnight soaking is shll necessary to develop workability and plasticity. ADVANTAGES economical, uniform, easy working, white and plastic. LIMITATIONS Requires overnight soak. USG Brands--Grand Prize and Red Top Finish Hydrate (Genoa, Ohio). Finish Quicklime is usually made from high calcium limestone. It is produced and used in areas where it is not economical to ship from the Ohio lime fields. Quicklime or "hot" lime requ slaking and relatively long peri of soaking for complete hydration and to develop the plasticity neces sary for easy application. ADVANTAGES economical because of its high putty yield. Easy working. LIMITATIONS Requires long slaking period. Unless handled carefully can cause serious bums in handling. USG Brand-- Red Top Finish Quick lime (Texas). GAUGING PLASTERS Lime does not "set" but hardens slowly. It likewise shrinks on drying. Therefore, gauging plaster is blended into the lime putty in proper propor tion to provide controlled set and strength, and to avoid shrinkage cracks when used as a finish coat. Red Top Gauging Plasters are carefully ground and screened to just the right particle sizes to make this plaster quick soaking and easy to blend with time putty. Gypsum gauging plasters are avail able in "quick set" and "slow set," making it possible for the mechanic to use the material which best suits him. This makes it unnecessary to add retarder or accelerator for regu lating the set of the finish. They are available as white gauging and local gauging which is somewhat darker in color. For brilliant white finishes, white gauging plaster should be used. MIXING A APPLICATION Gauging plaster is added to the lime putty in the proportion of one part of dry gauging to not more than 3 parts of lime putty by volume, or one part of dry gauging to not more than 2 parts of dry hydrated lime by weight. (Mixing on board--use 2 quarts of water in putty ring for each 12 qt. bucket of lime putty. One hod of lime putty equals approximately 36 qts. A 12 qt. bucket of lime putty, 35-40 lbs., contains 18-20 lbs. of hydrated lime on dry weight basis. Sift sufficient gauging plaster into this water to completely soak up the water.) After the gauging plaster is sifted into the lime putty ring and allowed to soak a few minutes, the materials are thoroughly blended to avoid gaug ing "streaks" and to provide uniform density in the finish coat. The gauged lime putty is applied over a partially dry gypsum base coat. Scratch in a thin coat, well ground into the base coat, and im mediately double back with a second coat, filling imperfections. (A third or thin "sweetening coat" is.sometimes applied to fill in any further imper fections that remain after the second coat has "taken up.") After the base coat has sucked most of the excess water from the finish, it is troweled to density the surface and help elim inate check cracks. As final set takes place, it is water-troweled thoroughly to pro vide a dense, smooth surface suitable for decoration. BB013 0103 45 Keene's Cement-Lime Finish Red Top Keene's Cement is a high strength, white gypsum plaster used with finish lime putty for extremely hard, dense surfaces. Although Keene's Cement is a gypsum material, it differs from other gypsum plasters in several particulars; it is slow-setting; it is the only gypsum plaster that can be re-tempered; and the finish coat re quires more troweling. Red Top Quick-Troweling Keene's sets faster and requires less trowel ing. It must be used with a minimum of 25 lbs. of dry hydrated lime per 100 lbs. of Keene's Cement. Keene's-Lime Finish is similar in i: fiRED TOP' KEENES . CEMENT many respects to a lime-gauging fin ish except that Keene's Cement is used in varying proportions, depend ing on hardness required, in place of gauging plaster. Keene's-lime finish should be used where greater resist ance to moisture, and greater surface hardness and resistance to abrasion are desired--as in hospitals, kitch ens, bathrooms and corridors. For medium hard finish, mix in the proportion of 50 lbs. of dry hydrated lime (100 lbs. lime putty) to 100 lbs. of Keene's Cement. For hard finish, limit the quantity of lime to 25 lbs. of dry hydrated lime (50 lbs. lime putty) to 100 lbs. of Keene's Cement. APPLICATION the finish coat is applied over a set base coat which has been broomed and is partially dry. (If base coat has dried out, spray with water before finishing; do not soak). Scratch in a thin coat well ground into the base coat and immediately double back with a second coat filled out to a true, even surface. Allow to draw up a few minutes, then trowel with water to a smooth glossy finish, tree of cat faces and other blemishes. Continue troweling until finish has set. AVAILABLE USG BRANDS RED TOP CHAMPION Gouging Planter (while) RID TOP STAR Gauging Planter (whilo) RED TOP Gauging Plantar (gray) RID TOP Gauging Planlar (gray) RED TOP Regular Kaana't Cnmant (while) RID TOP Quick Troweling Keene'a Cement (while) USG STRUCT0-0ALIQ SET WITH LIME PUTTY Quick net--10-30 min. Slaw net--43-AO min. Slaw icr--43-40 mir Quick *el--20-30 n 3-4 hourn CS 1-2 heurn IB 1-1 'A hours O LIMITATIONS For interior uses only. Where ex posure to water is extreme or con tinuous, use Portland cement-lime plaster. Apply Red Top Keene's Cement only over gypsum base coats of high compressive strength. STRUCTO-GAUGE Urns Finish USC Strccto-Gauge is a new high strength gypsum gauging plaster for use with varying proportions of lime putty to produce surfaces of extreme hardness and durability. Wherever Keene's Cement is used, Structo-Gauge Lime Finish may be used. With a faster set than quick troweling Keene's Cement, easier working characteristics and higher lime proportions, Structo-Gauge finishes are more economical than any other hard finish. With the same proportions of lime, Structo-Gacge finishes achieve much greater hard ness than a comparable Keene's Cement-Lime Finish. For medium hard finish, mix in the proportions of 100 lbs. dry StructoGauge to 200 lbs. dry hydrated lime. For hard finish, mix in the propor tions of 100 lbs. dry Structo-Gauge to 100 lbs. dry hydrated lime. APPLICATION Apply over a partially dry gypsum base coat. Scratch in a thin coat, well ground into the base and immediate ly double back with a second coat, filling imperfections. Water trowel to a smooth finish, free of all blem ishes. All troweling must be com pleted before final set. Clean tools and equipment immediately after each mix. LIMITATIONS Same as for Keene's cement-lime fin ishes. Gypsum Trowel finish Red Top Gypsum Trowel Finish is mill-prepared and requires the addi tion of water only. It is recommended for use over gypsum base coats where hardness and immediate decoration are required. Red Top Trowel Fin ish is available in most areas and is recognized for its easy working qual ities and pure white finish. 1 RED TOP* r trowel j- FINISH ADVANTAGES rated one of the hardest of all finish plasters, it provides protection against the most severe wear. It has approxi- BB013 0109 47 nately twice the surface hardness of irdLiary lime-gauging finishes. Nonlikaline, it will not injure paint or decoration and may be decorated as ioon as it has set and dried. Made of gypsum, it provides a durable and natural bond to gypsum base coat piaster. MIXING AND APPLICATION Rjed Top Trowel Finish requires the iddition of water only. Allow to soak io or 13 minutes and then mix to a smooth, lump-free mortar of the de sired consistency. Apply over a gypsum base coat which has set, but is not bone dry. (If base coat has dried out, spray lightly, before the finish coat is ap plied. Do not soak.) Scratch in thor oughly, double back and fill out to true, even surface. The finish should not exceed Yt in. thickness. Trowel the surface free of cat faces and other blemishes, using water spar ingly. Troweling must be complete before final set occurs. Work from unset edges to avoid joining marks. Gypsum Sand-Float Finish Red Top Sand Float Finish is similar in every respect to gypsum trowel finish, except that it is carefully for mulated with the correct proportion of properly graded sand. This pro vides a uniform, easy-working ma terial which eliminates the uncer tainty of job-mixed sand-float fin ishes. Available in its natural gray color, which requires painting for final decoration. Select lime-proof colors may be added which eliminates further decoration. APPLICATION same as for gypsum trowel finish ex cept that the final coat is finished with a wood, carpet, cork or rubber float depending on texture desired. Colored Finish Plasters Colored gypsum finish plasters are frequently used to produce a pre decorated finish of either a finely floated or textured surface. Use of colored gypsum finish plasters elimi nates the need for further surface decoration. This speeds the plaster ing job and results in lower costs. Col ored gypsum finish plasters are avail able in either factory-prepared colors or they can be produced on the job. JOB PREPARED FINISHES require addition of limeproof color pigments on the job to proper pro portions of lime putty, aggregate and Keene's Cement. In mixing this ma terial for a job, the lime-proof color should be thoroughly blended and mixed with the plaster to prevent color streaking and variation. It is also necessary to mix job-prepared colored interior finishes in sufficient quantities to complete a job. This eliminates color variation which would result from trying to mix a second batch to match the first. Keene's Cement-Sand Float Finish shall be mixed in the proportions of 100 lbs. of Keene's Cement to 50 lbs of dry lime and 400 lbs. of sand, wit' or without the lime-proof colors. .*$013 0 1 0 6 48 ORIENTAL Interior Colored Finish A factory prepared colored finish con taining properly graded aggregate ind select limeproof colors to insure :asy working qualities and uniform ity in results. Available in 6 pastel rolors and white, it requires no fur ther decoration and may be applied to produce many types of surfaces ranging from a very fine sand-doat Irtish to a ragged texture. It is highly resistant to abrasion because of its {reat hardness; avoids variations of tolor intensity which sometimes tccur when colors are mixed on the ob; permits early occupancy. $ te f?ORIENTAL' llintirkw caunwlllwl fiaanr tionally dry, it should be sprayed uniformly with dean water the night before finishing. Application is made in a two coat double back operation. Scratch in a thin coat well ground into the base coat and double back with a second coat, filling out to a true even sur face. The surface can be floated with a sponge, sponge rubber float or car pet float. The finish can also be ap plied in any desired texture except a smooth trowel finish. Do not use water while floating. ORIENTAL Exterior Stucco Factory formulated to insure color uniformity. Applied to exterior sur faces over a base coat of portland cement-lime and sand. Oriental Exterior Colored Finish is available in 11 pastel colors and white. Suitable for application on new work or for remodeling, it is an economical means for beautifying in two ways--texture and color. BB013 0107 AIXING AND APPLICATION tdd dean water only, hoe stucco into he water. .Allow to soak 20 or 30 ainutes and mix thoroughly to a mooth, creamy easy-working conistency. Must be applied to a set, half-green" base coat of gypsum faster. If the base coat is excep 49 MIXING AND APPLICATION Oriental Exterior Stucco requires only the addition of water on the job. When it is mixed and applied in the following manner, excellent brushed results may be obtained: 1. The suction of the base coat must be uniform, therefore, the base coat should be in a "half green" condi tion. If it is too dry, spray lightly. (See detailed instructions for mixing, applying, and curing of Portland cement-lime base coat, page 41.) 2. Remove loose and projecting par ticles from base coat, then apply a thin coat well ground into the base and completely covering it. Double bade and fill out to a uniform surface about in. thick, covering area from top to bottom, in one operation to eliminate joinings. Trowel three or four times before starting to texture. 3. For a float finish, use a cork, wood, carpet or sponge rubber doat, and float the surface to an even texture. 4. Do not use water in floating. 5. After setting, spray the surface periodically for several days to cure the finish. 6. Do not apply in freezing weather or before or during a rainstorm. FINISH PLASTER data Mix by weight of dry motorists Gmuglng Plawcr fa Lima ia STRUCTO-CAUGC to Uma 1:2 1:1 Color White or Gray O) White White Rntsh Taster* Smooth . Smooth Smooth Hardnoss in Kilograms (2) 34 54 108 Cowaroga 1 ton gouging 2 tons Uma eowar approx. tooo-uoo yd*. 1 ton STRUCTOGAUGE 2 tom Goto covor appraiu 1000-1200 yard* 1 ton STRUCTOGAUCE 1 ton of lima cowar approx. 600-750 yards. ( V Gray with "foeol" govging piortor. (21 Kilograms ragwrod to forth o 10 MM boil .0 1* into pfattor loco. 50 B) CO O ~ o b* a 00 SABINITE Acoustical Plaster TROWEL OR FLOAT a highly sound absorbent acoustical, plaster which can produce a trowel or float finish. It is applied over a properly prepared gypsum base coat, and is available in oyster white and four standard colors. ADVANTAGES High Sound Absorption--carries a .60 NRC in Trowel and .55 NRC in Float Finish. Readily Maintained--cleans with brush or wallpaper cleaner; may be spray-painted with only moderate loss of acoustical efficiencv. Fir* R.sistont--incombustible, min eral composition. Adaptable-- blends with any archi tectural design. Easily Applied--any good mechan ic, provided ordinary precautions are observed, can apply Sabenite. Economical--applied in two succes sive coats, 16 to 24 hours apart-- eliminates re-scaffolding. LIMITATIONS Mixing and application instructions must be closely followed. Designed for use on ceilings or wall areas noc subject to contact or high humidity. Sabinite is not recommended over radiant heating panels. Qoick Tr.w.llng Keene's te Umi Gypsum Trswd Finish Gypsum Fleet Finish ORIENTAL Finish 2<l Medium Hard 4.1 Hard Neat Neat Neat White White White Gray. 12 colon Smooth Smooth Smooth Root Root IS-- IS-- so 70 S3 Not. 31 Not. 31 2 tons Ktsns't 1 fen lime cover approx. 850*1200 yds. 4 fens Keene'i 1 ton lii appro** 1300*1700 yds. 1 approju 330-400 yds. I will i approx. 250-275 yd.. 1 i will approx. 250*300 yds. (3) Than an (lord fluid*, but ft* eggragoM in Itm ivrtec* dan not parmd an indication am o -- ^ wrtfi Ihi left. Q poe -0 51 MIXING AND APPLICATION Machine mixing recommended. Put 22 quarts dean water in mixer for each bag of SabDOTE. Mix until SaBDOTE weighs 15 to 17 lbs. net per 12-qt. pail (usually 3 to 5 minutes, depending on speed of mixer). To hand mix, place Sabdote in one end of dean mixing box. For each bag, add 23 qts. of clean water in other end. Hoe Sabdote into water. The mix will appear dry, but do not add more water. Hoe until Sabdote weighs 15 to 17 lbs. net per 12-qt. pail. Apply in 2 coats to a uniform total thickness of Yi in. over a base coat of . SABIN HE" s acoustical sS Red Top gypsum plaster. A full scratch and brown coat of gypsum plaster is required over metal lath, Rocklath plaster base, and mason ry bases (exduding monolithic con crete) to provide proper rigidity, strength, and a solid base for the acoustical plaster. Apply first coat \4 in. thick by scratching in and doubling back over a set, semi-green gypsum base coat that is level and thoroughly broomed or cross raked. If base coat is dry, spray lightly to reduce suction. Fol low immediately with a wood or metal darby, leveling SABDtrTE to provide a true, even surface for finish coat. Allow to set and to partially dry (at least overnight or longer de pending on job drying conditions) before applying finish coat. Apply finish coat to a thickness of 14 in. by scratching in and doubling back, over a set, partially dry base coat of Sabdote. Bring total thick ness to in. Leave surface uniformly level and free of trowel marks, work ing from wet edge. Finish ceiling panels in one continuous operation to avoid joinings. Trowel Finish--After water sheen leaves surface (about 30 minutes) trowel lightly to a uniform texture. Do not use water during troweling. Float Finish--float second coat 5 to 10 minutes after water sheen has left surface. Use a shingle, cork, or rubber float. Do not use water in floating. Directions for Applying SABINITE Acoustical Piaster Ovor .Rough Monolithic Cancreta: Over properly prepared rough monolithic concrete surfaces apply Bondcrete plaster not to exceed 14 in- thickness on ceil ings and in. on side watis. Appi the Sabinite over the set, semi green Bondcrete base coat, a specified. BB013 0110 52 DIRECTIONS FOR PAINTING USG ACOUSTICAL PIASTERS. Remove all loose dirt or dust by use of a vacuum cleaner. Paint should be water-thinned. Texolite Imperial or Standard is recommended. First coat, mix one part Texolite paste to one part water by volume. Second coat (if required), mix one part Tex olite paste to two parts water by volume. Spray on with any gun with a medium fine spray. DeVilbiss spray gun, type MBD, with a No. JO noz zle or equivalent, is recommended. Use JO to 40 lbs. pressure in the gun and 20 to JO lbs. on the paint. Hold nozzle 14 to 18 in. away from work. Use a slow, uniform motion. Cover surface in one pass. Do not pass over same area several times as this builds up paint unnecessarily. , Allow at least overnight drying between coats. If weather is extremely humid, allow additional drying as necessary. ADVANTAGES HI-IITE Finish-- it's snow white, with over 75% light reflection. Easy to Mix and Apply---mechan ically mixed, it works smoothly and easily under the tools. Attractive, Adaptable--can be given a stippled or stipple-perforated fin ish. Can be used in areas of moder ately high humidity, such as swim ming pools. Fire Resistant--Hl-LtTE will not bum or support combustion ... an important safety advantage. Low Maintenance Costs--can be decorated repeatedly with any good resin--emulsion or casein paint (TEXOLITE--Imperial or. Stand ard) without appreciable loss in sound absorption. 11o cioae HI-LITE Acoustical Plaster STIPPLE OR STIPPLE-PERFORATED Highest light reflective acoustical plaster developed by U.S.G. (.77.80), must be stippled or stippleperforated to provide its acoustical efficiency (.60). Available in white only. LIMITATIONS Hi-Lite must be machine mixed to develop proper density. Designed for use on ceilings or wall areas not subject to contact. 53 When perforated, a special per forator with rust resistant prongs should be used. Hi-Lite is not recommended for use over radiant heating panels. MIXING AND APPLICATION USG Hi-Lite Acoustical Plaster shall be applied in two coats to a uniform thickness of 3 >'. A full scratch and brown coat, either gypsum plaster or portland cement-lime plaster, that has been cross-raked is required over metal lath, gypsum lath and mason ry bases (except monolithic con crete). First Coat--Apply first coat of HlLm by scratching y% hard, imme diately doubling back to a total of over a set and dry, partially dry, or semi-green basecoat. Darby light ly to a level surface. Allow to set and dry fairly well (usually overnight) before finish coat. Finish Coot--Apply finish coat y thick to a set and fairly dry basecoat, scratching and doubling back leaving surface free of trowel marks. Work from wet edge to avoid joinings. When surface gloss has disap peared and surface is crisp and hard enough to give clean perforations, stipple the surface with a rice root stippling brush to a uniform texture. To obtain a stipple-perforated fin ish, perforate about JO minutes after stippling (when surface is hard enough to give clean perforations), but before set. Use perforator fur nished by the United States Gypsum Company. Perforations should num ber approximately 500 per square foot and should be at least l{t" deep. AUDICOTE Acoustical Plaster SPRAY OR HAND APPLIED A plastic, high-coverage material with excellent sound-absorbing prop erties. It has exceptional bonding characteristics, and is designed for use over gypsum basecoat plaster, Portland cement-lime basecoat plas ter or monolithic concrete. Available in Satin White and Special White. ADVANTAGES High Sound Absorption--carries a .60 MRC in darbied finish and .55 MRC if machine textured finish is desired. Low Mointonanco--tests reveal n> loss in noise reduction coemcien after two spray coats of TEX0LIT1 (Standard or Imperial), applied at BB013 cording to U.S.G. specifications for painting acoustical piasters. Arotcon may also be redecorated easily by direct spray application of a thin coat of Arotcon Plaster. Fir* Resistant--incombustible, ba sically mineral in composition. Low Cost--the most economical of our acouscical plasters. Versatile--because it can either be applied by machine or by hand in a variety of appealing finishes. LIMITATIONS Audicote is designed for use on ceil ing and wall areas not subject to contact. Acbicote is not recommended for use over radiant heating panels. While a rust inhibitor is used in Audicote Plaster, it is recommended that use of unprotected steel in the surface of monolithic concrete be minimized to avoid rust spotting of the finish. MIXING AND APPLICATION Machin* Mixing--Machine mixing is recommended. Add Audicote to water, using approximately 55 quarts of dean water per bag for first coat of acoustical plaster. For machine application of finish coat more water will be required--70 to 90 quarts, depending upon type of machine used and degree of texture desired. An increase in the amount of water used per bag will give a finer texture. If hand application of finish coat is required, use approximately 55 quarts of water per bag for finish coat. Mix for minimum of five min utes in mixer to develop proper consistency. Hand Mixing--If required, material must be hoed sufficiently to develop even consistency free of lumps. Machin* Application--First coat of acoustical plaster should be ap plied to thickness of Yt, leveled with a darby and pointed up with a trowel if necessary to provide a smooth and level base for finish coat. Allow to dry before applying finish coat, which should be Yt' thick. Hand Application--First coat of acoustical plaster should be applied to thickness of Yi . Level with a darby to provide a smooth and level base for finish coat, and allow to dry. Finish coat should be applied to a Yl thickness. After finish coat has taken up sufficiently, it may be stip pled, stipple-perforated, darbied or floated to produce desired finish. ta os o u o u 55 MEMORANDUM o ** > Specialized Lathing and Plastering Systems BRIDJOINT Lathing System ROCKLATH Resilient Lathing System BRACE-TITE Lathing System 2>inch Solid ROCKLATH and Plaster Partition Exterior Wall Purring System Column Fireproofing TRUSSTEEL STUD-ROCKLATH Partition PAGE 58 60 62 65 68 70 71 USG has developed a complete line of attachment systems employing the use of clips for attaching Rogelatb Plaster Base to wood framing, metal grillage, Tbusstzel Studs and masonry walls. These systems are designed to provide performance and economy in the construction of plastered walls and ceilings which offer: 1. Greater resistance to cracking 2. Reduced sound transmission 3. High fire resistance 4. Insulation 5. Vapor barrier 6. Economy o cioaa DESCRIPTION The Bridjoint lathing system uses Bridjoint dips to apply Rockiath Plaster base on walls and ceilings in such a manner that the ends (16-inch dimension) of the lath fall between and not on the framing members. The B-l field dip and 5's' B-2 comer dip are used for y$" Rock- lath. A Vz B-l field dip is used when Rockiath is specified. ADVANTAGES Crock Rociitant--because ends of gypsum lath do not fall on framing members, resistance to cracking is increased at these vulnerable points. Adaptable--This system facilitates application of Rockiath over nail able steel framing. Use ?'&* Rocklath with framing up to 16' o.c. and )A' Rockiath tor framing spaced up to 24' o.c. Economical--25% less nailing is re quired than conventional nailing of Rocklath plaster base to wood studs. On wood frame construction Comerite and nailings are eliminated in rhe internal angles. 58 BB013 0116 I DIRECTIONS FOR LATHING AND PLASTERING lathing--RoczlaTH is applied in such a manner that the ends of the lath do not fall on the framing mem bers. End joints are staggered in adjacent courses. A B ridjoint clip is used at corners of each piece of lath to support the lath ends which fall between the framing members. Rocklath is nailed to the wood or steel framing. (See page 16 for nail specifications.) Plastering---plaster in two or three coats to j^-inch thickness. (See page 36 for plastering specifications.) Estimating Quantities--B-l clips, per square yard; B-2 clips, one for each 16 inches of comer angles (or 75% of total lineal feet of comer angles). i ROCKLATH RESILIENT DESCRIPTION Rocklath Resilient Lathing System uses steel spring clips for attaching Rocklath plaster base to wood framing, steel channels or masonry. These resilient clips doat the Rocklath and plaster tree from framing members. ADVANTAGES Resistant to Sound Transmission-- National Bureau of Standards as signs average sound transmission loss rating of 52 decibels to a wood stud partition with R-l resilient clips, gypsum lath and plaster both sides. Crack Resistant--plaster cracking due to framing movement is gTeatly reduced. Where framing movement occurs back of lath and plaster, it is absorbed by the spring clips in much the same manner as automobile springs soften road shocks. One Hour Fire Rating--wood stud partitions with R-l Resilient Clips, perforated Rocklath, and }4-inch gypsum-perlite plaster proportioned 100 lbs. : V/i cu. ft. (scratch and brown coats) have a one hour fire rating. Economical--For a nominal increase in the lathing cost, the Rocklath Resilient Lathing System provides outstanding sound and crack resist ance features. DIRECTIONS FOR LATHING AND PLASTERING Lathing--apply Rocklath plaster base face out with the long dimensions at right angles to the framing members 16 inches o.c. Stagger end joints. Rocklath ends must occur over framing members and be secured with clips. Place a clip at even- inter section of Rocklath edges and fram ing members. Staple or wire-tie all corner bead to Rocklath. Do not nail Rocklath Plaster Base or accessories to framing. Where Resilient Rocklath ceiling joins conventional nail-on walls or partitions, a J^-inch thick furring strip (usually a strip of Rocklath 2 inches wide) should be nailed to joists at ceiling angle to compensate | j j ; j i ! ( strength; well* ond coiling* or* rtw* obi* to comp*n*at* for normal from* mov*m*nt, ond th* pla*f*r lurfae** ar* prot*ct*d again*! cracking. for the J^-inch furring or R-l Resili ent Clips. Use a B-2 Bridjoint Cor ner Clip in place of R-2 Resilient Comer Clip. If walls are resilient and ceilings nail on, nail furring strip to the studs at the ceiling line. Do not use nails in comer angles. CAUTION Perforated Rocxlath is not recom mended for use on ceilings when applied with resilient clips. Plastering -- plaster to H'inch grounds with sand or perlite aggre gates. On ceiling work use only plain for % indi tt--i fvrrmg dteiwiot*, in coding construction. Rocklath and apply plaster in three coats (do not "scratch-doubleback"). Where one hour fire rated wood stud partition is required, plas ter to }^-inch grounds with gypsumperlite plaster proportioned 100 pounds gypsum plaster to V/i cubic feet perlite (scratch and brown coats). Estimating Quantities--R-l, R-3, R-5 clips--Estimate 5}^ to 6 per square yard. R-2 dips--1 for each 16 inches of comer angles (or 75% of total lineal feet of comer angles). lt-1 and R-2 combined, 6 per square yard. K for matowry or solid conooto eon* itrucrion. ] I BRACE-TITE Lathing Systems DESCRIPTION The Brace-Tite Lathing System attaches Rocklath plaster base to standard metal grillage (J^-inch cold rolled channels not over 16 inches o.c.). This system is also used as a base for direct application of acousti cal tile. ADVANTAGES Vareatila--may be used for plastered ceilings or for acoustical tile base without plaster. Strong--gives support across the full width of Rocklatb. Clip provides spring tension to the center. Easy to Erael--requires no special tools. Maximum spacing of K* chan nels 16' o.c. Two-Coat Plastaring--permits use of scratch double-back method over plain or perforated Rocklath. Plas ter thickness is j^-inch. Firaproof--tire resistive ratings of one to four hours are obtainable. DIRECTIONS FOR LATHING AND PLASTERING Lathing--I. Place starter clip over 5i-inch channel at juncture of chan nel and side wall. {Note: Ij hot rolled channels are used, hand crimp clips tojit snugly over channel legs). 2. Place Rocklath plaster base on top of starter clip loop and at right angles to channel. Engage BraceTite field clip over channel and hook it into starter clip loop. On first course of lath, crimp field --:r,, clip wire to accommodate slack caused by starter clip loop project ing from wall. (See B.) Use B-l B ridjoint clip at each end joint of lath on first course only. End joints should be staggered and fall between channels. Use a B-l Bridjoint clip on both sides of lath end joints, See (C). Upon completing a course of Rocklath, slip a B-l Bridjoint clip over each end joint so that it is firmly supported. 3. After first course of Rocklath is completed, no further crimping of wire is necessary. Succeeding courses are rapidly applied by looping each field clip over channel and inserting hook into eye of preceding field clip. Complete last course by cutting Rocklath to fit remaining space. Hang field clip over channel end, insert hook end under preceding clip, pull back and snip off excess length. BRACE-TITE Aeouiticol lathing system. Place the full loop end of Brace-Tite Acoustical dip over end of each % inch channel at juncture of channel and wall. Rocklath plas ter base shall be applied at right angles to channels, and the half loop end of the field dip snapped over the % inch channel. Succeeding courses shall be applied in same manner using Bl-A Bridjoint clips (prongs fiat on tile side) in lieu of the B-l clips used for plastering. Plastering--apply gypsum piaster in two or three coats %-inzh thick, using sand or perlite as aggregate. If one hour fire rating is required, apply gypsum-perlite plaster proportioned 100 lbs. : 2Yi cu. ft., 2'6-inch thick over perforated Rocklath. Estimating Quantitias--for %-inch channels, 16 inches o.c.: one BT-1 Starter Clip for each channel abut ting a vertical plane and at any interruption of channel. 5H to 6 BT-1 or BT-A Field Clips per yard. 3!/2 to 4 B-l or B-1A Bridjoint Field Clips per yard. For %-inch channels, 12 inches o.c.: BT-1 Starter Clips, same as before. to 8 BT-1 or BT-A Field Clips per yard. B-l or B-1A Brid/OINT Field Clips, same as for 16inch spacing. BB013 0122 64 2-IN. SOLID ROCKLAIH and Plaster Partition DESCRIPTION A studless non load-bearing partition consisting of J^-inch V-edge, Long Length Rocklath plaster base, held vertically by door and ceiling run ners, up to 12 feet in height, and plastered on both sides. ADVANTAGES Save Space--Saves 40 to 60 per cent of space occupied by conventional partitions. In every five lineal feet a 2' partition creates one extra square foot of usable space over a 4Yi partition. Lightweight--only 16 pounds with gypsum-sand piaster and 9 pounds with gypsum-perlite per square foot of finished partition (25% to 40% lighter than commonly used masonry partitions). Strong--official impact test rec ords show that a 60 pound weight traveling through a full arc fall of 4 feet failed to produce a discernible craclc on a full size partition after three successive blows. One Hour Firo Rating--with gyp sum plaster sanded 1:1 for scratch and 1:2 for brown coat or gypsumperlite proportioned 100 lbs. to 2 cu. ft. on scratch coat and 3 cu. ft. on brown coat. Where one hour fire rat ing is not required, plaster may be sanded 1:2 for scratch and 1:3 for brown coat. DIRECTIONS FOR LATHING AND PLASTERING Floor Runnor-- USG Metal base or wood runner. Indicate positions of floor runners with chalk lines. When USG Metal base is used, metal floor clips should be nailed approximately 24 Inches o.c. Snap metal base side plates over shoulders of the clips. Wood runner should be milled l5lj x 2 inches from select stock re sistant to splitting. Coiling Runnors-- Apply USC L-shape ceiling runner using H-ind BB0I3 0123 6! m- ~-,p concrete stub nails or power driven nails approximately 24 inches apart. Mail to a line plumbed up from center line of floor runner. If ceiling is suspended type, wire-tie L-shape runner to lath. Grouting--Fill metal'base with gyp sum grout using uniform V-groove. Recommended grout mixtures: 100 lbs. gypsum plaster to V/i cu. ft. of perlite, or 2S0 lbs. of sand. Ail metal door bucks shall be grouted, providing uniform V-groove prior to erection of lath. Lathing--Cut Long Length Rocklath to allow a minimum of J^-inch and a maximum of 1 inches top clearance. Set in V-grooved base sec tion with top edge against vertical flange of ceiling runner. Edges should be plumb and butting. To hold lath to ceiling runner, snap two USG Ceiling Runner Clips through the top or center row of slots. Lath is cut and fit ctosely around conduits, outlet boxes and steel door buck struts. One side of opening is covered with metal lath strips backed with No. 30 asphalt felt (usually 3 to 5 inches wide; applied with hand stapling machines. Partitions (up to 9 feet high) are then horizontally braced in the fol lowing manner, see photo below: (1) Punch hole in center of each lath slightly below mid-point for bracing clip; (2) insert bracing clip; (3) spring a partition length 24-inch cold rolled channel into bracing clip with channel legs pointing down; (4) insert remaining bracing clips and spring channel into place; (5) wiretie channel ends at abutting parti tion angles to comerite; (6) parti tions 9 to 12 feet high require two horizontal braces at third points in stalled as described above; (7) wedge vertical brace (usually wood lx4's or l^'ilH' angle iron) between floor and ceiling every 6 feet and wire-tie to horizontal channel. Plastering-- Apply a full J'S-inch thick scratch coat of plaster with maximum of 3 hour set, to each side of the lath. In no case should application of scratch coat to second side of lath be delayed longer than the setting time of the scratch coat applied to the first side. Scratch lightly in horizontal direction only. Let scratch coat set a minimum of 16 hours before browning. Apply the brown coat as follows: (1) After the scratch coats have set firmly and have partially dried, the brown coat should be applied to the unbraced side, bringing it out to within Hi-inch of ground dimension for finish coat. (2) When this brown coat has set firmly, (not less than 3 (a hours) remove braces carefully fron opposite side and apply brown coa to that side in similar manner. () ejt EXTERIOR ILL FURRING System DESCRIPTION A simple practical system for furring exterior masonry walls using USG Adjustable Wall Furring Brackets, %-inch channels and Long Length Insulating Rocelath (J^-inch thick by 24-inch x ceiling height). ADVANTAGES USG Furring Bracket--Heavy gauge galvanized steel with serrated edge which holds channel firmly in place. Permits proper wall alignment. Adjustable--uneven walls can be furred quickly to true, even surface without expensive, time consuming "shimming." Lew Cost--large 2 ft. wide ceiling high sheets of long length Rocelath plaster base go up quickly. Uni formly even plaster base saves plas tering material and labor. Vapor Barriar--provides inexpensive and efficient safeguard against con densation within the wall. Insulation--offers the equivalent of J^-inch of fiber insulation board when erected with the required minimum air space between exterior wall and lath. DIRECTIONS FOR LATHING AND PLASTERING Application of Matal or Wood Floor Runner--Nail single metal base clips to rough floor not over 24 inches o.c. Snap the sideplate over the clips. Fill the back of the base with grout and form a V-groove as grout stiffens and before it sets providing a Jf^-inch BB013 0126 rrptcw fussino of cxtikios masonrt wail 68 --*?/ ground for plastering. Alternate. A milled wood runner may be attached to the rough door by nailing with cut nails or concrete stub nails in the center groove. Application of Calling Runnar-- Attach L-shaped ceiling runner to the construction above as required, locating it by plumbing up from the floor runner. Where furring does not extend to the construction above, install horizontal furring channel 4' to 6' below top of lath. Application of Furring--for furred walls up to 9 feet high, locate furring brackets to the masonry walls not over 4 inches from columns or other abutting construction. Locate brack ets at third points vertically and not over 36 inches o.c. horizontally. For walls from 9 to 12 feet, locate brackets vertically at quarter points. Set brackets in mortar joints or use 2-inch cut nail to attach bracket to mortar joints of brick, clay tile or cement block, or in the field of light weight aggregate blocks. Use one 5'8-inch concrete stub nail or one power driven nail per bracket on monolithic concrete. Lay %*i&ch furring channels horizontally on the furring brackets with the legs down, plumbed in line with the base. Wire tie to the bracket with a double strand of 18 gauge tie wire. Bend down excess bracket length. Lathing--Apply gypsum lath with the long length vertical, butted light ly with the foil facing the furred space. Set bottom of lath in the groove of base grout, clipping top of lath to the ceiling runner and wire-tying (over a nail) at the edges to intermediate horizontal channel furring. Cut and fit gypsum lath to allow 54' clearance around window frames. Apply a 3-inch strip of metal lath over each Rocklath Plaster Base joint under window. Plastering--Apply scratch, brow C9 gg and finish coats to a full %-inch ove face of lath. Cut plaster base coat tJ with the edge of the trowel alon ^ margin of metal window frames. *+ il ill R: FIREPROOFING SIEEL COLUMNS with ROCKLATH and PLASTER 1, VA. 2, 3 AND 4 HOUR FIRE RATINGS 1--1 Va Hour Rating-- Vi"--16"x48" Perforated ROCKLATH, cur as required, is applied vertically against the column and fastened with a double strand of 18 gouge fe wire approximately 2" from the ends ond 15" o.c. 1-A bead, set at each corner, establishes piaster grounds for 1 hour and s/i" grounds for 1 Vi hour ratings. Apply gypsum-sand plaster proportioned 1:2 Vi and any finish coat. DESCRIPTION Rochlath Plaster Base wired in place against structural steel column, and plastered with gypsum cement plaster and sand or perlite aggregate in proportions and thickness required to give fire rating desired. In certain higher ratings, 20 gauge galvanized 1-inch hexagonal mesh wire fabric is used in addition to the Rocklath. ADVANTAGES Fireproof---column fire ratings of 1, 1^, 2, 3 or 4 hours are obtained, lightweight--6 pounds per square foot oi completed surface area tor 1 hour protection to 11 pounds ior 4 hour protection, low Coat--Standard materials used. Easily attached, economy of plaster ing over gypsum lath. A 2 Hour Rating is obtained by lath ing in the same manner as indicated above except that the 1-A bead must be set to establish I" plaster grounds over the lath and gypsum-periite pias ter, proportioned 100:2 Vi must be used. 3 Hour Rating--Lath the same os for 1 hour rating except set 1-A bead to provide 1 Vi" grounds by snipping ex panded flanges 12" o.c., bending back and stapling to ROCKlATH. Apply Gypsum-Perlite plaster propor tioned 100 lbs.: 2 cu. ft. for scratch coat and 100 lbs.: 3 cu. ft. for brown coat. Use ony standard finish coat. 4 Hour Rating --Apply a double thicknew of Vt" long length ROCKLATH Plaster Base cut os required, vertically against the column and fastened with double strand of 16 gauge tie wire about 4" from top and bottom ond 24" o.c. Wrap 1" hexagonal 20 gauge galvanized wire fabric over the lath and set 1-A bead to establish 1 Vim grounds. Apply gypsum-perlite plaster proportioned 100 lbs.: 2 cu. ft. for first Vi* of thickness and 100 lbs.: 3 cu, ft. for second Vi". Use any stan dard finish coat. azio cioaa 70 TRUSSTEEL SIUD ROCKLATH Partition Assembly DESCRIPTION A non-load-bearing partition of Trussteel Studs, Rocklath Plas ter Base with Trus-Lok Clip attach ment. and plaster. Over-all thick nesses: 5}t', 6', and 8', depending on stud width. ADVANTAGES Floxiblo--The open web design of the Trussteel Stud allows encase ment of small pipes, conduits, heat controls, and small ducts horizon tally and vertically without weaken ing the partition structurally by chasing. Web members are easily cut for larger pipes or ducts. Versatile--2^4', 3J4', 4', and 6' Trussteel Studs provide wall thick nesses to meet job requirements. Strong--Strength of studs is derived from strategic use of metal in a truss design--not from bulk weight. The partition assembly of Trussteei. Studs, Rocklath plaster base, and plaster has more than adequate strength for building construction practices and is nationally accepted by building code authorities. t I 3 71 Lightweight--This partition assem bly weighs approximately ;0 lbs. per square foot when plastered with per lite aggregate plaster, and approxi mately 15 lbs. per square foot with sand aggregate plaster, in any Trusstzzl Stud width. Fira Resistant--Built of incombus tible materials. One hour fire rating is obtained when perforated Rocxlath plaster base is used and plas tered with gypsum-sand plaster 1:1, 1:2, or with Stxtjcto-ute piaster or gypsum perlite 100:2J^. Sound Reduction--This partition assembly has good resistance to sound transmission, attaining aver age sound transmission loss ratings of 48 decibels with sand aggregate plaster, and 44 decibels with perlite aggregate plaster, in tests at a na tionally recognized laboratory. Economical--Material costs are low, job erection fast--provides installa tion economies for mechanical trades. DIRECTIONS FOR LATHING AND PLASTERING Lathing--install Trussteel studs not over 16 inches o.c. (See pages SoSi for details.) Studs shall be located approxi mately 2' from all door buck jambs, abutting partitions, or other con struction. With steel bucks, an additional anchorage stud is required at each jamb. AU comers shall be framed with a stud approximately 2' from each side of the internal angle. Securely wire-tie studs adjacent to door bucks to the jamb anchors. Start lath application at the bot tom with long dimension of Rocxlath at right angles to the stud. The first course of lath shall be set in O BB013 TL-2 Starter Clips spaced approx imately 16' on center along the run ner track and secured to the studs by TL-1 Field Clips hooked around the stud and over the top of the lath. The end joints of the Rockiath shall occur between studs, staggered in alternate courses, and joined to gether at the corners with B-l Br:d;oint Clips. Where wood grounds are wire-tied to the studs the lath shall be held in place by driving a nail into the ground at each stud, with the nail head held tight against the lath and projecting up from the ground 3d of an inch. Succeeding courses of Rocklath shall be attached by inserting the lath into the top portion of the TL-1 Field Clips of the preceding course and securing the top edge of the lath to the studs with TL-1 Field Clips. The top course of lath shall be cut to the width required, B-l Clips placed on the previous course of lath in each stud space and the lath se cured to the runner track with a TL-3 Finisher Clip driven into the lath, or shall be secured by wiretying through the lath around the stud or stud shoes with a double strand of tie-wire twisted tight over a nail on the face of the lath. In the case where ceilings are lathed the last course of lath shall be cut to ht as required and held in place with cornerite stapled to the Rocklath and wire-tied or stapled to the celling lath. The course of lath immediately over metal frames shall be set in a groove provided in the grout, if grout is used, or shall be set in TL-3 Clips clipped to the runner track, or shall be wire-tied to the studs over a nail on the face of the lath. Where ceilings are lathed, the last course of lath shall be cut to ht as required and held in place with cornerite stapled to Rocklath and wire-tied to metal lath. Cornerite shall be used on all in ternal angles, and comer bead at external comers, by stapling to Rocklath plaster base. Metal lath reinforcement over frame corners shall be 133i' x 19' pieces or 9' x 48' strips of 2.5 lb. self-furring metal lath stapled to the Rocklath. Metal door frames shall be securely anchored to the floor by two power driven anchors or equivalent attach ment through a clip at each jamb. Jamb anchor clips shall be welded in each jamb at top, 12' down from top, 27' from top and t8' from bot tom. Use runner track at head of buck to receive studs over opening, runner to turn up 4' each side at the jambs and wire-tied to studs used as door frame struts, or use a hori zontal channel extending to third stud each side of frame approxi mately 4' above frame to which studs are tied and grout in over frame. Secure studs to jamb anchor clips by engaging in notches and wiretying securely in place, using double strand of 18-gauge tie wire. If wood door bucks are used call for rough bucks of same width as BB013 0131 73 studs, and of not less than l%* stock with the jambs running to underside of construction above and well anchored top and bottom. For stair rails, lavatories, etc., bolts welded or locked to channels, angles, or plates shall be anchored to studs prior to lathing. For cabinets, 1' wood grounds may be tied to studs prior to lathing or 8-A picture mould may be tied over Rocklath to studs. Plastering -- plaster to H-inch grounds using gypsum-sand or gyp sum-perlite plaster. Plaster may be applied in two or three coats. Grout ing steel frames with piaster prior to lathing is recommended. Estimating Quantities--for studs spaced 16 inches o.c.: TL-2 Starter dips, two for each Trussteel Stud; TL-1 Field Clip, 5H to 6 clips per square yard each side; B-l BRtDjoitrr Field Clip, 5l/> to 4 per square yard each side. Figure Two TL-3 Finisher Clips per stud if lath goes to underside of concrete slab, otherwise figure wire tieing or cornerite depending on conditions. Specialized Lathing and Plastering Systems Metal Lathing Systems PAGE Metal Lath Resilient Lathing System 76 2-Inch Solid USG Metal Lath Partition 78 TRUSSTEEL Stud Metal Lath Partition 80 Metal Base 84 METAL LATH RESILIENT Lathing System DESCRIPTION A system composed of metal lath, steel furring members and spring clips that provides a floating attach ment of plastered surfaces to struc tural members. ADVANTAGES It oilers greatly increased protection against plaster cracking due to struc tural movement, and a considerable reduction in the transmission of sound through walls and ceilings. It is adaptable to wood supports, sus pended ceilings, hollow partitions, and masonry or concrete surfaces. ESTIMATING QUANTITIES No. 100 Clip, runner channels 3'-0* o.c.. furring channels 12 inches o c. J40 clips per 100 ?q. yds ; furring channels 16 inches j.c. . 264 ciins per 100 sq. yds. No. 200 Clip, walls iclip spacing 16 1 ) i BB013 0134 Svtpdftddd CtiHng--Showing oppiicotion of No. 100 Clip for sviotodtd Ctiling con* ifrvcfton. Tho dip providoi rvailionr artodi* mpnl of fwring dionooi to runnor chonntt by rtpiocmg imp of fhd tip wir. Easy to tract. Wd Pram* Cdnrrw<tion*<5howing op plication of No. 200 Clip on wood midand iouti and on wood htrnnq on moionri wolU. Cl!p provtdd rp*ii<nt artaeftmont motol Iprh ond protect ptoitor Aniih. 76 inches o.c. along studs spaced 16 in. o.c.), 610 clips per 100 sq. yds. Ceil ings (clip spacing 12 inches o.c. along joist spaced 16' o.c.), *44 clips per 100 sq. yds. No. 400 Clip*, Trcssteel Studs, 16 in. o.c., dips spaced 12 inches o.c., *80 dips per 100 sq. yds. Spacing 16 inches o.c., 600 dips per 100 sq. yds. No. 500 Clip Spacing of furring CheeneU,... Quantity of Spacing of dip* p Clips lOO 1*. yds. 12 inches 24 inches 496 16 inches 18 inches 604 24 inches 12 inches 496 BB013 Macanry Surf<iS^owmq um of No. 500 Clip on coiiiAg under concrete joist and on masonry walls. Clip is also mod on other mosonry surfaces. Provides furring and resilient attachment of moral loth. TKUSSTEEl Stud ParrtHon--Showing gso of No. *00 Clips tpoced 16 inches along studs. A V*m pantii rod is wirod into tha notch on outsida Pang* of dip to prorido resilient furring member for moral lath. CLIP Ho 400 TIUJSJTfIL. smo PAATmON 2 CJ (I 77 2-IN. SOLID USG METAL LATH and Plaster Partition DESCRIPTION A non-load bearing partition that finishes to an overall thickness of 2 in. May be erected using % in. chan nel studs with Diamond Mesh metal lath or with Yi in. Riblath without channel studs. ADVANTAGES Saves Space--saves 40% to 60% of the space usually occupied by con ventional partition. One Hour Fire Rating--when plas tered with sanded plaster muted 1:2, 1:2 for scratch and brown coats. Highly Crack Resistant Good Sound Transmission Rating-- 38 average decibel transmission ioss. Lightweight--only 18 lbs. per part; tion square toot with gypsum-san plaster. DIRECTIONS FOR ERECTING Stud Partition--Snap partition Line 9C io E ioaa 78 on floor and ceiling . . . Fasten Ztype ceiling runner to ceiling . .. At tach double base clips, 16' o.c., to structural floor with concrete stub nails. (See pa%e 84) . . . Insert Y in. channels into door clips and fasten to ceiling . . . Wire-tie Diamond Mesh lath in conventional manner . . . Snap on metal base side plates and grout base. Sfudless Partition--Snap partition lines at floor and ceiling . . . Fasten lath to USG L-type ceiling runner nailed to the bucks .. . Provide tem porary bracing by placing % in. channel horizontally near mid-height of partition for partitions up to 9'-0* height. Partitions 9' to high require two horizontal braces at third points tie to lath 24 in. o.c. Place a vertical lH in- angle brace not over 6 ft. o.c. to hold the lath in position until brown coat on side opposite bracing has set. 4, v L-type ceiling runner to structural ceiling or furred-down ceiling . . . Attach double base clips, 24' o.c., to structural floor with concrete stub nails, snap side plates in place and grout, leaving V-groove to receive V% in. Riblath . . . Erect ceiling height Yi in. Riblath vertically by dropping into grouting groove and wire-tying top to L-type ceiling run ner not over 8 in. o.c. . . . Metal door bucks shall be provided with dips along jamb and wire-tie the in. Riblath to these dips .. . Where wood bucks are used, wire-tie the DIRECTIONS FOR PLASTERING 2 In. Solid Motal Lath Partitions-- Apply scratch-coat to side opposite braces or channels, allow to set and partially dry . . . metal door frame shall be slushed full with plaster ... On studless partition apply browncoat to side opposite braces and al low to set before removing braces. Apply brown coat to previously braced side bringing it out to finish CD grounds. On stud partition, apply back-up coat on channel side to full grounds. Apply brown coat to lath u side. Apply finish coats to both sides. 1O-- U >4 79 TRUSSIEEL STUD METAL LATH and Plaster Partition DESCRIPTION This truss design stud permits the erection of hollow, non-load bearing partitions in which ducts and pipes can be easily fitted and concealed. ADVANTAGES Lightweight--Finished partition weighs 13 to 17 lbs. per square toot. One hour fire roting--when plas tered with gypsum--sand mixed 1 2, 12. Strong--Withstands up to 30% greater transverse loads than l)4ai. steel channels. Economical--Requires no special tools or structural framing, goes up fast. Can be used with metal lath or Rocktath plaster base. This system is available in the following sizes: Stud lengths, 7 to 20 ft.; stud widths, 3J4, 4 and 6 in. It contains the following parts as shown in sketch at right: (A) 22 gauge top and bottom runner tracks; (B) 7 gauge rod studs spot welded. (C) Shoes for attaching studs to run ners. These shoes allow an adjust ment up to 3 in. B B 013 0 t3 B 80 :3 STEP BY STEP ERECTION Runner frock i aligned and attached to concrete floor and coiling with stub nails at 2 f?. intervals, or wired to suspended ceiling every 24'. Stud* are secured to runner track by means of two snop'On attachment shoes at top and RECOMMENDED STUD SPACING Typo of loth TRUSSTEEl Stud Spocing 2.5 lb. Diamond Mesh Lath 3.4 lb. Diamond Mesh lath 2.75 lb. 'hm Riblath 3.4 lb. '/i* Riblath 3.4 ib. vr Riblath 4.0 lb. Vt" Riblath y- ROCiOATH Plaitcr Base 12 inches 16 inches 16 inches 19 inches 24 inches 24 inches 16 inch** bottom by 'wrtinq flange between runner track and floor or ceiling. leg of shoe is then snapped over side of stud and wire tied. Metal loth is applied to both sides of studs with 18 gauge galvanized tie wira. J 1 FINISHED PARTITION THICKNESS jji AND Stud Width LIMITING HEIGHTS 'u l'i if Ftathed Walt Thickeess Metal lath aad Nestor--hemal Craaads Maximem i ; Partition -t 'j Haight Steds : \ 2r ir u- hi 2'A" 3 4" 6' 4* iy." S'A" 7'A" 9' U' 15' hj 1 13' 18' 21' I ' 16' 20' 22' ; 20' 2*' ~ .? u I 81 A GENERAL DATA FOR PARTITIONS r*HW|ir;. 3 Hollow PYROBAR Tila plostarad two sidas 4# Hollow PYROBAR ploirarad ona sida 4** Hollow PYROBAR plaitared two sides 2' Solid ROCKLATH Soma 2' SOUO Mafal Lath {studs) Soma (sfudlats) TRUSSTEEL stud--matol lath 21 20 25 16 10 1B 18 19 Gypsum sand 1:3, 1:2 Gypsum sand 1.3, 1:2 Gypsum sand 1:3, 1:2 Gypsum sand 1:2, 1:3 Gypsumparlita 100:2. 100:3 Gypsum sond 1:2, 1:2 Gypsum paHita 1:2, 1:2 Gypsum sand 1:2, 1:3 TRUSSTEEL stud--ROCKLATH 15 STRUCTO-LITE or Gypsum Sand 1:2 parforafad ROCXLaTH GENERAL PLASTER BASE DATA FOR CEILINGS Staat joists--matol lath Soma Soma 2*/im rainforcad conerata slob on ribloth Staal joist construction with mafal lath furrad or suspandad Soma Soma Par+ororad ROCKLATH ortochad by BRACE* TTTE systam--diannals 16' on cantors Soma os oboaa plus IA gouga diogonol wlras through dips Soma os abova axcapt dsonnals 12r on cantors and 1A gaugo diagonal wira through dips H' Parfocotad ROCKLATH attaoiad by BRACE* T1TE systam' chonnals 12" on cantars and 20 gouga hax. mash 82 V* gypsum sand 1:2, 1:3 gypsum pariita 100:2, 100:3 1# gypsum paHita 100:2, 100:3 y** gypsum sand 1:2, 1:3 %r gypsum partita 100:2, 100:3 1' gypsum partita 100:2, 100:3 H' STRUCTO UTE Plostar or gypsum paHita 100:2, 100:3 Z\ STRUCTO UTE or gypsum paHita 100i2Vs a' STRUCTO UTE or gypium pdit, 100i2'/l -------------------------------------__ QD o I' STRUCTO UTE or 9rpH>m pHrt# 1 00i2 '/, u o p* * o 4%' 4' S'/,' 2' 2* 2' 2' 4'/i to 7V,` 4'/i lo 8' 3 hour* 3 hours 4 hours Yi hour 1 hour 1 hour t hour 1 hour 1 hour 39 dodbols 43 d.b. 37 d.b. 37 d.b. 38 d.b. 37 (>!.) 40 44 to 48 Fir* Rating 2 hour* 3 hours 4 hours 2 hours 3 hours 4 hours 1 hour 2 hours 3 hours 4 hours 13 foot 17' 17' 12' 12' 14' 3'4r 14 to 20' Do ponding on width. i m ab o b, r.i O * 33 v STEP BY STEP ERECTION USG METAL BASE DIRECTIONS A "plastered-in" metal base system for partitions and walls, composed of floor dips or masonry wall dips and steel side plates. May be used with metal lath or Rocklath plaster bases or masonry plaster bases. Side plates: 18 gauge steel, 10 feet long by 2]A inches high. ADVANTAGES Easy Application--Snap-on attach ment feature permits faster installa tion with automatic and independent adjustment on any rough or finished floor. Vonatilo--Internal and external cor ners can readily be formed on the job tor any condition with USG notching tooi. Safety--Adds no combustible mate rials to the construction and protects base of the partition. USG METAL LATH For Column Fireproofing This time proven system provides a 1, 2, 3, or 4 hour nre rating. It util izes self-furring Diamond Mesh lath and accessories and typical metal lath construction. Grounds: One hour--gypsum sand 1:2, 1:3; two hours--1' gypsum-periite 100:2, 100:3; three hours -- 1 Y% gypsum-perlite 100:2, 100:3; four hours--1 ' gypsum-perlite 100:2, 100:3. BB013 0142 USG READY-FORMED METAL ARCHES DESCRIPTION USG Metal Arches are the practical and easy way to form symmetrical arched openings in either new con struction or remodeling. Precisionmade for doorways and recesses. Available in three styles, seven sizes for finished openings 20' to 70H>*. USG Metal Arches are made of gal vanized steel, perforated for proper plaster keying. ADVANTAGES Varsatila--Choice of size or style. Easy to vary size and shape for any size openings and partitions of any thickness by combining sections in various combinations. Easy to oroct--ready to put in place as they come from the carton. There are no forms to make; no comer bead to bend or shape by hand. No special preparation of the rough opening is necessary. Economical--Since these arches combine plaster base, comer bead and plaster grounds, there's a saving in time, labor and materials. DIRECTIONS FOR ERECTING The arch sections fit perfectly over 2 z 4 studs and any type lath, or over masonry of similar width. For other partition thicknesses merely split arch soffit, overlapping for thin partitions and filling in gap with metal lath for thicker walls. Studs on each side of the arch should be spaced 1 Y> inches wider than the desired finished opening. .Assemble the metal arch units on the door. Join the units, using connector pins. Strike exact center of the opening on header. Then insert the assembled metal arch in the opening over the lath. Nail in place, temporarily. Then level the arch and nail it se curely in place with lath nails through the solid part of the flanges. Vertical comer beads are aligned to the metal arch with connector pins. TRUE C1RCIE ARCH Ha. II -- IO' radios Na. 23--1544' radios Table of Erection Details style Arch width FlnliMd Opening No. 11 No. 22 No. 23 No. 36 No. 64 No. 55 No. 66 20' 3116' 31 'A' 3716' 4916' 61 W' 7016' Ofifirniirn from Arch 8ai te Header 10' isy*' 11%' ii' 1216' 13' 13' Spacing between Sfwds er Bucks (Rough Opening) 21'6 33' 33' 39* 51' 62' 72' tiiitit 86 C lo a g teft u * Plaster Problems RemediesTheir Causes and Basecoat and finish coat plasters are so closely interrelated that the treatment oi problems pertaining to their use will be handled simultaneously in the following pages. All Red Top basecoat and finish coat plasters are carefully manufactured and thoroughly tested before shipment, and any troubles or problems experienced in tneir use are normally found to be caused by job conditions. INTRODUCTION As a general rule, most piaster problems result from the following conditions: 1. Atmospheric conditions. 2. Conditions due to set--fast or slow. 3. Improper heat and ventilation. 4. Improper application or thick ness of basecoat or finish coat. 3. Improper proportioning of aggre gate or improper mi-ting. 6. Improper workmanship. 7. Improper plaster base applica tion. 8. Improper bond. 9. Poor aggregate (improper grada tion, impurities, etc.). Plaster problems are classified under the specific type of condition wnich exists. These problems are dis cussed in order under these following types and specialty products: 1. Plaster Cracks. 2. Weak, Soft Walls. 3. Bond Failures. 4. Set and Working Qualities. 5. Color, Surface Stains and Blem ishes. 6. Acoustical Plaster Problems. 7. CovtR Coat Finish Plaster Problems. PIASTER CRACKS It should be understood in reviewing this broad subject that a plaster slab is not a delicate material and will take considerable abuse without cracking. It cracks only when some excessive external force is applied. or when some excessive internal strains are induced wtthin it. The stresses, conducive to cracking, are normally caused by movement in the building frame, or other components of the building over which plaster is applied, or by variations in the at mosphere surrounding the plaster slab. Cracking of piaster occurs more readily where the plaster siab is weaker or thinner than standards permit, and if stresses are encount ered before the piaster is dry ana has attained full strength. Proper plaster bases are important to prevent plaster cracking. They also must be sound--this is equally Important in the foundations and in the structural framing. Structural weaknesses cannot be corrected in lath and plaster worn. One of the largest single factors causing plaster cracks is the lack of understanding the need for and use of proper heat and ventilation. Cracking of Partitions installed in line with tha face of concrete col umns and beams--Reinforced con crete frame buildings and steel frame buildings with columns and beams encased in concrete may induce cracking of plaster in partitions when such partitions are located so that the piaster plane continues from the plaster base over the column and/or beam face, and is bonded to the concrete. This cracking can occur either at the joining oi the concrete and the plaster base, or in the field of the partition, whether the plaster BB013 0146 88 base is masonry, metal lath or gyp sum lath. The cracking is caused by difference in movement between the concrete and the partition mass-- the severity of cracking varying with the age ot the concrete and the at mospheric conditions at the time ot plastering. The cracking tendency will be reduced it the concrete has aged a year or more, or when build ing temperatures are moderate and stable tor a reasonable time prior to plastering. In normal construction, where plastering occurs tour to eight months alter the pouring ot concrete, and is frequently done during colder and changeable temperature conditions, cracking may be minimized or elimi nated by either, (1) relocating the partition to come several inches back from the column and/or beam face, or (2) if plaster base is installed in line with column and beam by ap plying heavy paper (No. 30 asphalt felt) over the concrete, lapping onto the plaster base about 1 inch, and then applying diamond mesh metal lath over the paper, scatter-nailing it 12' on center to the concrete, using stub nails, and fastening it to the edge of the plaster base by nailing to masonry, wire-tieing to metal lath, or stapling to gypsum lath. This avoids a bond of the plaster to the concrete, thus reducing stress due to movement of column or beam in relation to the partition mass.  " if'O v* 5 oi-rg 5 ^ 5 - s 2a ! -srJ| 2 C -- o -fi ,. " o a c o 'u 'a o `5 " * 0- I so. c m 0 0>.. rt " .*i2o *5a N a. 2 . o. c ;-o --0 ;--5IO --a ao- a * * s 0 = a. a ?* ! ^oe >* :^ : c *s *s 0 ; i: o -a i"5 .o2 --O -5 So 0. o 11: K 3>> ao 2* = 5 j' -1 - ci : 2-u a? io i 5. '< ;S n J oA 2^ *o 2o j Ji5 I .. > i 9_ Si o al > |E i2 E 0> _j 1 o >. 5S Mi ii2 !*5i 2 51 g 3 ! * I 1 | a. s :Si :!J 9S wa aI. fa --55 .*. wE 3*8 - a 5 '2- S 2 I C2" -0>c o,, :-a* iO -s6 O -a -2 o 2 a 9 0 Si 9 S3? 0|i 2s ao- 09 09 O * U o 19 % COLOR. SURFACE STAINS AND BLEMISHES PLASTER PROBLEMS AND REMEDIES i-S J5 *of OX >! --o n* *5 3 | E > o "5 i3 J15 i_C 21 i!& IO f> .i "5 > I 2 ! "3 3 2 j: : e .1 5 II il io!t2w ei 8 ii i I iii III 111o C -5 * *s o 5*1 8W 2Q "*5c S 0O -0 0* .0 <E oo - > w *s-=e *2 55 r: e s o 3 * ^5 -S 5 *2 S 'Si S-- Jo !<I o tCSega2 > g-: -I s O.I I2 ,1i tl 1 2 jii -5 uil 5 2 0 X-S o o- w * 2-2 ' O 2I -- u J 3 3*5 *3 c II o 1Q.-S 2 o . *3l o6 O S s' 2 e a. 5 -a >* >. c = e <c 0C 9^^-0o a 2 -- i3 i** ; ao *S?- - u iil.2 8 -2 SJ3 _ *o J *1 -SI^0*5 s\3 i S S1 3 ^_* Ja .a * = .S " -- ft; o ft* CJI M 2. COLOR, SURFACE STAINS AND BLEMISHES . > o a &e~Z w ss 5 *5 in a *5 11? e .5 14 " v> > sli 5S ii-lil2 030 c1 1*0 ** 2 g 6 i oc ; oT ^ - 0 0 ol o 0 i *?c --. a. 30 -o 5* sg > _** 'Sawt I ao : ? Ul I3! E * c0 > a 9 >. * *5 Z E a a*. vo 2* isl? ^ ?_' 31 o* J J Ul .C ss j}l 5 ? ?6 ? -Si a. *3 5c! K E 3 ^ > o > O to 1*1 l l1l IUS vq 23 1 1 2M j^ im :o 2* | a2 ow? Ec 20 ?5; 5 si O 0^ O < E ji 83 so 3 S.-S oMl O o aa ?I Oa a. o i2 O5 |: m ia 3w Ay .Sis si i -II Sis ,,e* CW9 ill > o <& *! ioi * u WEAK. SOFT WALLS a o * j: 4 u "a o o u M'S. (J 4. BONO FAILURE OO LU o LU uQ 4e a I 5| LU oc u *1 * - s i -? .21 Oi 0 o <c CO s o .o II ^ 1-* 4^=0*2?* 2 * o2l1 2oi1 0 ai*12 ci ci-2 5 -a I-o ot'j io'o1 "i *51 *1 *I 2-1: --C E . at oc OSC -Js3 !|Qo;' vi| ai .>*! .2*- a., g .1 I .S i!uo SI!! 03 O Of CL. fj 2 -a lt j CO S5 2*5 Sooii-o8"s5~i.J:Oc 8! sI 2 : 81-s U Aw --6 .g X>>tti fe: S | 3- e*1i ;z= 2! J Ihi 6o io O6Oo &2> 2-o O Q. *6 ?*s > OO *e= 2S *oo s-'=c J*o= ;* 4 u; 5 -5 o'i ! USJ e--o ,0 e _ o2 - w a. gou C0OLDu K.iC 6 9 oa 4. BONO FAILURE V . ACOUSTICAL PLASTER PROBLEMS ? c tQ iE li i aa.. oa. -0 o o- ?o CO a fi *9 a. c e > 3 ^ 5C 8^5 --i- 8 -a o -o o i ^i JoS ^o I2 i k j a - ** -- <5 wcl -eE 0 2** S2* i --52 2 : ; a=- pi i n I 2 -a * i *o i-il 1** Ua. al sS 0 2C i> S- j3 -O a. S Ev i cI >, 3 5 <3 2 ; is 3 - 2- -r- E3 Q I - 0oo -S2'5 ii;2 24",> o -9 Z2 3 4> 3> 7* * *Q 5t s Bo o0 . U s I -O i ? I2 ,-| 2c si E 2 o -o ^ I -s r | z V . 2 2? 2 Co c - O - 51' <^ .S2 V3 O 3 JL c - o ;< - 2 ci 6 ; 3 . S-- g ja s S 3 : S !? a ="3 * *."3 Sj 8 f| Is S 3 r `r * 8 : i e0 8 2k s3i =ai r 5. ro o-SE 2 "o >? = _ J3 6 6 H 2CL *3 a2 e3 a us* Eo 6 o^ z: 1 a n .c 9i- -2 6 O) o u MEMORANDUM BB013 0150 How To Inspect A Plaster Job Approximately 80% of the visible wall surface in the average building is plaster. It is fundamental that all those involved in the plastering operation cooperate to obtain the best pos sible job. This section attempts to point the way to achieving such an objective--a quality plaster job. Proper inspection of a lathing and plastering job requires a complete understanding of job details, schedules and specifica tions. All walls must be judged within the framework of the drawings and the specifications on which the contract is based. It is most important that these drawings and specifications be complete, accurate and easily interpreted. 101 BB0I3 0139 SCHEDULE OF INSPECTION Job impaction* should bo mad# at tha following stages:-- A. When job is ready for lathing and plastering. 1. Determine that the brands and types of materials delivered to the job are in accordance with specifica tions and approvals granted. 2. Determine that proper storage facilities are provided for the mate rials. (See page j6, paragraph J.) B. When lathing has started but be fore plastering has begun. C. When base coat plaster is being applied. D. When finish coat is being applied. E. When job is completed. PLASTER BASES A. A plaster job is only as good as the base over which it is applied. Generally, plaster bases can be clas sified under these headings: 1. Suction Type--Gypsum lath and fiber insulating lath in which the water of the plaster mix carries gypsum into the porous surface, forming tiny keys which hold the plaster to the base. 2- Mechanical Type--Metal lath, in which the lath is embedded in the plaster and, In effect, forms a rein forced plaster slab. 3. Combination Type--Gypsum block, clay tile, other masonry and perforated gypsum lath, in which both suction and mechanical key combine to hold the plaster to the base. B. The most commonly used bases, along with points that should be checked prior to base coat applica tion are: 1. Unit Masonry (gypsum block, day tile, porous brick or rough conCrete block) a. Has correct mortar been used for laying? (See pages ij-rg.) b. Are walls straight and true? c. .Are any structural cracks evident? d. Have proper grounds been in stalled? (See page IJ.) 2. Gypsum Lath o. Has it been applied according to manufacturer's specifications. (See page 16.) b. Have proper grounds been estab lished, angles and comers reinforced? (See page /6.) 3. Metal Lath a. Have specifications of manufac turer been followed for proper nail ing or tieing? (See pages 26-28.) b. If suspended, furred or contact work, have proper weights of lath and spacing supports been main tained. (See pages 26-27.) e. Have proper grounds been pro vided? 4. Insulation Fiber Board Lath a. Check for correct application. b. Check for proper grounds, angle and comer reinforcement. 5. Monolithic Concrete a. When bond plaster is used, h? surface been prepared and maten applied according to manufacture! specifications? (See page j8.) 0910 eioas 102 SUSPENDED GRILLAGE Spacing of hangers and channels shall be in accordance with sparings recommended for the type of hanger and weight of metal lath used. Runner or furring channels shall not be let into or be supported by abutting walk. Place runner chan nels within 6' of walk. GROUNDS The thickness of base coat plaster is one of the most important elements of a good plaster job. To insure proper thickness, grounds should be prop erly set and followed. Grounds may be defined as wooden strips, corner beads (plumbed and straight), metal base screed, or metal casing beads applied at the perimeter of all open ings and other locations. In addition to these, and especially on walk with no openings, and on ceilings, plaster screeds should be installed to insure plumb and level surfaces. Plaster screeds are either dots or continuous strips of plaster applied to required ground thickness to permit proper plumbing and leveling. Grounds should be set to obtain the following minimum plaster thick nesses: 1. Over gypsum lath, and fiber insulating lath..................... !... 2. Over brick, clay tile, gypsum block, or other masonry............... 3. Over metal lath, measured from face of lath............................Yi plastering materials The plastering materiak generally in use today arc gypsum cement plaster (See page jS), gypsum mill-mixed base coat plasters (See pages jS & 39), hydrated finkh limes (See PSe 44), gypsum gauging plaster (See page 43), sand (See page 33), vermiculite (See page J4), perlite (See page 34) and water (See page 33). After determining what materiak are specified for use on the job, refer ence to the pages indicated above will describe the nature of each material and point out precautions that should be taken for storing it before it k mixed into plaster. JOB CONDITIONS Sm page* 36-37--This phase of the inspection is most important and, in many cases, will determine the success of the entire operation. An accurate check of the following points will prove well worthwhile: A. Storage 1. Has material been properly stored on the job for maximum protection from weather and dampness? B. Heating and Ventilation 1. Have proper heating and ventila tion been provided? .11 no time should any plastering be performed without proper heating and ventilation. A principal reason to for this k that circulation of air at the right temperature is necessary to carry od the excess water in the plaster, helping to avoid "sweat- O out" conditions. IT 103 2. In enclosed areas where adequate normal ventilation through doors and windows is not provided, sup plementary artificial ventilation must be provided. 3. In colder climates during the late fall, winter and early spring, the building should be heated in the nor mal range of 55 to 70 degrees tor some time prior to plastering and maintained at a uniform tempera ture in this range during all plaster ing and after the completion of the plaster work. TWO COAT VERSUS THREE COAT WORK Sm page 36--The architect's spec ifications and the plaster base will determine what plastering method will be used. There are two general ways of applying plaster: 1. Two-coat work. 2. Three-coat work. Except over metal lath, long length gypsum lath, fiber insulation lath, and wood lath, either of these two methods with the plaster properly mixed and applied can be employed. MIXING Sm pagm 35--A mechanical mixer is preferred to box mixing, because it is easier to assure that the plaster aggregate and water are more evenly mixed. Keep the mixer continually clean, which is most important, be cause partially set material is a powerful accelerator. When mixing by hand, plaster and sand first should be mixed dry to a uniform color in a mixing box, and the water added and the plaster hoed into the water immediately and thor oughly mixed to a proper consistency. Remember a number 2 shovel gen erally used to add sand to the mix carries approximately 15 pounds. Therefore, a 1:1 mix would use 6 to 7 number 2 shovels to 100 pounds of gypsum plaster. A 1:2 mix is 12 to 14 shovels, and 1:5 mix is 18 to 21 shovels. When perlite or vermiculite aggre gate is used instead of sand, remem ber the proportioning is wight of gypsum to volume of aggregate. (See page 33 for Proper mixing propor tions.) SCRATCH COAT Section on "Plaster Bases"--(page p) stated that there are three gen eral types of plaster base: suction type, mechanical type, and a com bination of both. Let's approach the actual application with this in mind and, as a result, know what to look for to help assure a good job. A. Application over Suction Type 1. Is the base properly applied and ready for plaster? (See pages t6.) 2. Is the correct aggregate being used in the proper proportion? (See pages 32-35-) 3. Is the building properly heated and/or ventilated, as suggested under Section on "Job Conditions." 4. Is scratch coat being applied to correct thickness and left in proper condition to receive the brown coat? (See page j6.) BB013 0162 104 B. Application over Mechanical Type Observance of the same precautions as indicated above should be checked, and it is recommended that nbered plaster be used, as fiber prevents the passage of excessive mortar through the keys and holds plaster to lath until set. C. Application over Combination Type The same requirements as apply in (A) above should be followed. BROWN COAT Once the scratch coat has set and is partially dry (usually overnight is sufficient), the brown or second coat is applied. Of course, precaution must be taken by the inspector to assure himself that the plaster is being prepared with the proper ag gregate correctly proportioned. (See pages JJ 34-) This coat of plaster, together with the scratch coat, forms the backbone of the plastered wall or ceiling, and it is important to see that it is applied to full grounds. All brown coat work should be left rough under the rod or darby to provide `tooth" for the finish coat. The use of excessive water in rodding or darbying the brown coat, which leaves the surface smooth and slick, is not good practice. SET OF BASE COAT PIASTER The proper setting time for base coat plasters is generally from 2 to 4 hours after mixing, and this should be checked for close conformity on both the scratch coat and the brown coat operation. The danger of ``quick set" plaster is that there will not be sufficient time to get the plaster from the mixer to the walls without retempering on the mortar board, and such retempering will produce a plaster of lower than normal strength. The correction for "quick set" is to add the proper amount of retarder in solution with water at the mixer. If plaster does not set for 5 to 6 hours, no harm will be done to the resulting plaster surfaces, but a "slow set" of the plaster (generally one tak ing more than 6 hours) should be avoided by adding accelerator in a dry state at the mixer, as such plas ter may be subject to a "dry out" (Set page 95), particularly in hot, dry weather, and will have a lower than normal strength when finally set. The setting of base coat plaster is indicated by the hardening of the plaster and by a darkening of the surface as the set takes place. The portion of the plaster which has set but has not yet thoroughly dried will be darker in color than the unset portion of the plaster. This accounts for the mottled effect in base coat plaster which appears as the set is taking place. FINISH COAT In addition to gypsum-lirae putts trowel finish (See page 44), the mosi common types of finishes are Keene': o cement-lime putty finish (See pag> ^ 46), prepared gypsum trowel finis! (See page 47), gypsum-sand float fin- O z 105 ee page 47), Orientax Interior (See page 49), USG Acoustical :rs. (See page J/). terallv, all finish coats are apto a properly prepared base >i gypsum plaster (See page 43). : mixing and application of fin als, it is most important that ^commendations of the manu facturer be followed. These recom mendations, along with mixing di rections, are printed on each bag and can also be found in the finish plaster section of this book. (See page 43). The visible success of the job is now at stake, and the required measures should be taken to finish correctly. UNITED STATES GYPSUM COMPANY DISTRICT SALES OFFICES Further information about items mentioned in this manual and complete details about all other U.S.G. products are available at offices located in tne following cities. ALBANY ALBUQUERQUE ATLANTA BALTIMORE BIRMINGHAM BOSTON (N*wton Cantr., MaicJ* BUFFALO CHARLOTTE CHICAGO CINCINNATI CLEVHANO (Clav.iand Height!, Ohiol* DALLAS DENVER DETROIT GRAND RAPIOS * Mailing Addrott HARRISBURG HOUSTON INDIANAPOLIS JACKSONVILLE KANSAS CITY LOS ANGELES LOUISVILLE MILWAUKEE MINNEAPOLIS NEWARK (Clifton, N. J.l* NEW HAVBR |Hamdn. Conn.)* NEW YORK OAKLAND OKLAHOMA CTTY OMAHA PEORIA PHILADELPHIA PHOENIX PITTSBURGH PORTLAND PROVIDBHCE (Warwick. R. L|* RICHMOND SACRAMENTO ST. LOUIS SALT LAKE CITY SAN ANTONIO SAN DIEGO SEATTLE SAN FRANCISCO SYRACUSE ID. Win, N. Y.J* WASHINGTON (Arlington. Va.)* g, qj o u o 0* u ITtTf I The Greatest Name In Building 9910 e io a a