Document 2q61V2N0aQevravKNLG39poer

American Society of Heating and Ventilating Engineers Guide, 1934 and which are constructed of porous brick and lime mortar. For good workmanship, the leakage through hard brick walls with cement-lime mortar does not exceed one-third the values given. These tests indicate that plastering reduces the leakage by about 96 per cent; a heavy coat of cold water paint, 50 per cent; and 3 coats of oil paint carefully applied, 28 per cent. The infiltration through walls ranges from 6 to 25 per cent of that through windows and doors in a 10-story office building, with imperfect sealing of plaster at the baseboards of the rooms. With perfect sealing the range is from 0.5 to 2.7 per cent or a practically negligible quantity, which indicates the importance pf good workmanship in proper Table 1.. Infiltration through Walls Expressed in cubic feet Per square foot per hour* Ttpb op Wall Won) Velocitt, Miles peb Houb 5 10 15 20 25 30 in. Brick Wall {plastered"" 1.75 4.20 7.85 - 12.2 18.6 22.9 0.017 0.037 0.066 0.107 0.161 0.236 13 in. Brick WalL__.... 1.44 3.92 7.48 11.6 16.3 21.2 0.005 0.013 0.025 0.043 0.067 0.097 Frame Wall, with lath and plasterb 0.03 0.07 0.13 0.18 0.23 0.26 Frame Wall, with lath and plaster4 0.02 0.05 0.10 0.15 0.20 0.25 oThe values in thi9 table are 20 per cent less than test values to allow for building up of pressure in rooms and are based on test data reported in A.S.H.V.E. research papers entitled. Air Infiltration Through Various Types of Brick Wall Construction, and Air Infiltration Through Various Types of Wood Frame Con struction. (See References on p. 102). bWall construction: Bevel siding painted. No. 1 common butt-edged sheathing, building paper, wood lath and 3 coats gypsum plaster. eWall construction: Cedar shingle, shiplap sheathing, building paper, wood lath and 3 coats gypsum plaster. sealing at the baseboard. It will be noted from Table 1, that the in filtration through properly plastered walls can be neglected. The value of building paper when applied between sheathing and shingles is indicated by Fig. I, which represents the effect on outside construction only without lath and plaster. The effectiveness of plaster properly applied is no justification for the use of low grade building paper or of the poor construction. of the wall containing it. Not only is it difficult to secure and maintain the full effectiveness of the plaster but also it is highly desirable to have two points of high resistance to air flow with an air space between them. The amount of infiltration that may be expected through simple walls used in farm and other shelter buildings, is shown in Fig. 2. The infil- 94 Chapter 6--Air Filtration Fig 1. Infiltration through Various Types .of Shingle Construction tration there indicated is that determined in the laboratory and should be multiplied by the factor 0.80 to give proper working values. WINDOW LEAKAGE The amount of infiltration in cubic feet per hour per foot of crack .for various types of windows is given in Table 2. The distinction between crack and clearance of a wood sash is shown by Fig. 3. For window and o to 40 eo OO too /eo MO *60 *90 gOO ggO /MftLTRArro* ae CF.H. Peft $0- Ft or Wall Fig. 2. Infiltration through Single Surface Walls Used in Farm and Other Shelter Buildings 95