IECC 2009
There is some confusion over the requirement for continuous insulation. Table 502.2(1) requires continuous insulation in Climate Zone 3 (for instance), but the text on the preceding page seems to eliminate the requirement. Sec, 502.1.2 U-factor Alternative allows the use of the U-value in Table 502.1.2, and as you look in Climate Zone 3, under Walls Above Grade, and Metal framed (as is the case of the building in question), the U-value is .084 which equates to an R-value of 11.9. This is quite different than the R 13 + 3.8ci that is required in Table 502.2(1).
The written word in 502.1.2 U-factor Alternative is clear enough, but it seems odd that the criteria would be so different than Table 502.2(1). So the question is.... Why would anyone use continuous insulation (that is so tricky to detail especially with a cultured stone veneer) when the code allows the U-value method which has a lower R-value requirement besides? And why would the code allow two completly different methodologies and solutions to the requirements?
What am I missing?
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Gary Pitts AIA
Rees Associates, Inc.
Dallas TX
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