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Gable wall insulation question

DIWhyMe | Posted in General Questions on

Hello. I’m new, and I’ve tried searching the articles and q&a and haven’t found an answer to my question. I restructured my roof and I am making it a conditioned vented attic. I’m using 1” polyiso foam boards to make baffles with a 1”  air gap between them and the 5/8 plywood to provide airflow from soffit to ridge vent as I’ve read about on here. Then I am having r-49 of agribalance opencell spray foam added for a total of r-55. My questions are if I don’t intend on installing drywall, is it ok to bury the 2×10 rafters, and what do I do with the gable walls. I will be adding a register to condition the space to make sure there isn’t a humidity issue. Do I just have them spray against the gable wall sheathing? Do I add polyiso there? I don’t see how I could vent it, and I would worry about a space behind the boards collecting moisture. None of the articles addressed this. I’m a home gamer that knows just enough to know that I don’t know much. Any advice is appreciated. I live in zone 6. New York. 60 miles north of the city.

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  1. user-2310254 | | #1


    Your post is confusing. It sounds like you are combining two strategies: conditioned attic and ventilated (unconditoned) attic. Can you clarify?

  2. DIWhyMe | | #2

    Sorry for the confusing wording. It’s a conditioned attic, but instead of spraying foam directly on the underside of the roof deck, I’m spraying under baffles made of polyiso that are spaced 1” under the roof deck, which allows continuous airflow from soffit to the ridge vent. This is mentioned in the article, creating a conditioned attic. Down in the paragraph titled “will the Insulated roof include ventilation”. There were no recommendations for the gable ends in that write up. The roof deck can dry to the air vent space. The walls of the house will be 3” of polyiso on top of the sheathing with outtie windows. They will have to dry to the inside. So as far as my gable walls go, they will have to dry to the inside if I’m understanding the web of articles I’ve read. Any advice or more questions about the setup, let me know. Thanks.

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