Ventilated or Non Ventilated Attics

[Peter Hughes]

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?

[Michael R. Boyett]

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.

[rwand1]

Here is the most recent discussion of ventilation at...

http://www.nachi.org/forum/f16/cracked-shingles-22321/

[rcooke]

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

... Cookie

[rwand1]

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.

[Peter Hughes]

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.

[Barry Adair]

[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.

[rwand1]

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.

[Brian A. MacNeish]

[quote=phughes]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]

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...e_housing.html

[Kenton H. Shepard, CMI]

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.

[Michael R. Boyett]

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...r/article/1520 for more detail.

[jkogel]

Originally Posted by kshepard

Attics which have been converted to bedrooms are perfect examples of non-ventilated attics.

Actually they ARE ventilated, with doors and windows.