BCAB #1558 - Alternative Insulation Values, Sentence 188.8.131.52.(2)
December 19, 2001
Re: Alternative Insulation Values, Sentence 184.108.40.206.(2)
The subject building is a wood frame house. The exterior wall assembly is constructed with 38mm X 89mm studs with RSI 2.1 (R-12) fibreglass batt insulation in the stud cavity. The wall assembly also includes RSI 0.88 (R-5) polystyrene foam insulation exterior sheathing.
Reason for Appeal
Sentence 220.127.116.11.(2) states alternatives to the requirements of Table 18.104.22.168., "Minimum Thermal Resistance of Insulation" may be determined through the use of acceptable engineering principles.
The appellant contends that ASHRAE heat transfer calculations should be an acceptable method when determining alternatives to the requirements of Table 22.214.171.124. The ASHRAE handbooks are referenced in the Environmental Separation part of the Building Code, particularly Sentence 126.96.36.199.(1) stating: Heat, air and moisture transfer shall conform to good practise such as described in the ASHRAE Handbooks. Using this method, the appellant's assembly would have an effective value greater than the effective value of a similar assembly using the insulation criteria of Table 188.8.131.52.
Building Official’s Position
The Building Official does not support alternatives to the insulation requirements of Table 184.108.40.206. derived by the use of ASHRAE calculations.
Appeal Board Decision #1558
It is the determination of the Board that ASHRAE procedures are an acceptable reference for determination of good engineering principles as referenced in 220.127.116.11.(2).
George Humphrey, Chair