Trying to understand Code required insulation for condensation control
jollygreenshortguy
| Posted in Building Code Questions on
When 2021 IRC raised insulation levels it did not make a corresponding increase to the condensation control insulation levels. Consequently 2021 has lower ratios compared to 2018.
Does that mean these lower ratios are actually fine from a condensation control perspective? If so, then shouldn’t they work equally well for 2018 insulation levels?
Ex. Zone 7
2018 | Total R 49 | Condensation Control R30
Ratio 30/49 = 61%
2021 | Total R 60 | Condensation Control R30
Ratio 30/60 = 50%
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Replies
The original numbers were based on Building Science Corp research and estimates. They wanted to use ratios, not hard numbers, but the code council thought that would be too complicated.
I agree that the numbers should have changed with the overall R-value update, and I use the original ratios. The way the code change process works, someone needs to propose and defend an amendment.