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Roofs and Walls: Interior vs. Exterior Insulation

erikdavitt | Posted in General Questions on

I am curious if anyone knows the reason/science behind why the ratio of internal to external insulation is smaller in walls then a roof? For example, in my zone, Zone 6 about 51% of the insulation should be on the exterior of a roof vs 36% for a wall. Is it because walls are less likely to have moisture build up due to condensation vs a roof?

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  1. MartinHolladay | | #1

    You have double-posted your question. To see an answer to your question, go to the GBA page where you also posted the same question:

    1. erikdavitt | | #2

      Thanks for your response as to why the ratio requirement is greater in roofs.

      It’s nice to know the reason behind a regulation.

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