Unvented Attics

Hi all,

I’m a student doing a project on Unvented Attics. I was wondering if anyone here knows where I could find data on how many Unvented (or conditioned attics) there are, or on how quickly they’ve gotten more popular. I know Home Inspectors must see them from time to time. This information doesnt seem to be publicly available anywhere, although it would be useful to have.

Thank you. I really appreciate any tips anyones able to give.

Jordan Taylor


I have never seen a purposely conditioned attic.

I have been in some that had nice big fat leaks in ducts that made being in them much more pleasant :slight_smile:

I’ve been inspecting for over 11 years and have yet to see my first encapsulated/conditioned attic space.

I have been in enclosed attics in south Texas in August with the attic temperature below 80 degrees with an OAT over 100. Check the Building Science Corp website and anything written by Joe Lstiburek.



I suppose it is how you define attic. I see ‘cathedral ceilings’ in one story bungalows and ‘one and half story’ homes, and the odd flat roof, once the attic is conditioned, or not even there, it is living space, and not called an attic anymore, even though in all these cases what you have is unvented space between roof sheathing and ceiling.

An attic is a uninhabitable enclosed space in these parts.

Follow up question:

What is your opinion on how the lack of venting affects the asphalt shingles?

The InterNACHI article says “asphalt shingles may fail prematurely due to increased exposure to heat” but also implies they may not. The building science article doesn’t address this.

I suppose different climates could produce different results. But here in Southern California, the summer heat can be pretty brutal on a roof.