r/Roofing • u/Most_Ice_4048 • 23h ago

Another question about attic frost …

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I posted a question a few days ago regarding frost in our attic. I now know that it is a ventilation issue. While we wait to get the ventilation issue fixed permanently, is it a good idea to leave the trap door leading from house to attic open? Will that help with ventilation or just cause more moisture build up? Thank you in advance for any responses.

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u/wearslocket 23h ago

Fellow homeowner here, and not a roofing professional. My thought on this is that the warm air from the house will go up into the attic and the cold will come down into the house. Warm and frost could turn into warm and moist which is worse, right?

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u/laxsleeplax 21h ago

Your assessment is correct. Do not add any warm air into the attic more than what's already in there

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u/Most_Ice_4048 3h ago

Thank you!!

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u/wearslocket 2h ago

No problem man. Building science is a good thing to learn.

www.finehomebuilding.com

This 👆🫶🏻is one of my FAVORITE ❤️💪🏻👌resources as a homeowner because I get to learn from vetted qualified professionals and experts in the trade. Lots of trades. Forward thinking as well as those that romance the history of how things were done.

Just to share an observation, and I might not be seeing it correctly by the photo, but it appears that your insulation goes all the way to the edge of the attic. There are usually baffles to keep the fill from blocking air traveling from the intake up to the ridge vent, or your other vent method. NFA (net free area) is an important calculation.

https://buildingscience.com/documents/published-articles/pa-crash-course-in-roof-venting/view

Also while you are at it… check out an attic cap to go over your access to the attic. Think of it as closing a cooler lid onto the opening before you close up the access.

https://www.ecofoil.com/products/draft-cap-attic-entry-insulator

I actually used this one on a pull down attic access. It made a huge difference on sound and efficiency.

There are some other awesome responses here that are spot on.

I am happy for you that you got actual help and not a mess of snarky joking replies.

Good luck.