Ventilated or Non Ventilated Attics

So, now days there is a lot of discussion on whether or not to ventilate an attic.

What are the thoughts out there in Inspector land?

Can you give examples of those discussions? I’ve definitely missed those and would like to read up on this. I have seen the pros/cons and discussions regarding crawlspaces but nothing on not ventilating attics.

Here is the most recent discussion of ventilation at…

http://www.nachi.org/forum/showthread.php?t=22321

A good read
.http://www.sprayfoaminsulate.com/PDF/UnventedAtticsWithSPF.pdf

… Cookie

Good info, but I would not be eager to use or endorse foam applied directly onto the underside of the roof sheathing. If you have a leak you are in big trouble.

I’ve seen a lot of the comments in books. Now how about in Practice?

Has anyone had any experience with Un-ventilated attics?

My experience has shown that older style un-insulated attics have excessive aging of the shingles. I can’t speak about all the new foam attics.

I certainly agree with Raymond. I’ve never seen an attic that will not leak at some time. So when it does, what happens.

Here in Texas / Dallas area, most of the HVAC and water heaters are in the attics. Another situation to think about.

[quote=phughes]

Has anyone had any experience with Un-ventilated attics? Yes

I can’t speak about all the new foam attics. No one really can they are all too new, at least around here. I did one of the first ones I’m aware of in this area for the Plano Housing Authority about 4 years ago.

So when it does, what happens? Same as any other leak except leak may go undetected longer. Building materials rot and WDI/WDO appear. Homeowner or insurer are out whatever it costs to repair.

[quote]

Hope this was useful.

When I was at the Toronto Home Show in October, I spoke to a foam insulation company and they did not recommend spraying directly onto the roof decking fwiw.

Go to: www.buildingscience.com and search for attics + venting. The attic you’re talking about is the best candidate for the “conditioned attic” treatment. Its been used quite a bit in the BUILD AMERICA program, Search there also.

Go to: www.buildingscience.com and search for attics + venting. The attic you’re talking about is the best candidate for the “conditioned attic” treatment. Its been used quite a bit in the BUILDING AMERICA program, search there also:
http://www.eere.energy.gov/buildings/building_america/affordable_housing.html

Attics which have been converted to bedrooms are perfect examples of non-ventilated attics. You can use spray foam or fiberglassto insulate them, but the net effect is the same.

A conditioned-air space doesn’t care how it looks, it reacts according to the laws of physics.

The US Dept of Energy newsletter this month contains an interesting article on this topic.
Read this:

then go to http://resourcecenter.pnl.gov/cocoon/morf/ResourceCenter/article/1520 for more detail.

Actually they ARE ventilated, with doors and windows. :wink: