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ajnabi 08-21-2008 06:38 AM

(conditioned space) closed cell insulation on rafters.

I have an space over my garage which I am turning into an office. It needs insulation and new roofing shingles--going with 30 year GAF/ELK architectural shingles.

The plan is to use closed cell foam on the rafters. There is almost not attic space--just a 1.5 foot section at the peak of the roof. This will mean no ventilation. In other words this will create a conditioned space.

From all I've read this is the ideal way to go. The one issue I have is that the roofer is balking because he thinks there must be ventilation to cool the shingles. I don't think that this will be the case since it is the build up of heat inside the attic that causes the heat problem. The only thing to heat up now is the decking itself and the shingles, which should have the outside ambient air cooling them.

Does anyone have experience with this combination of closed cell and shingles?


inspectorD 08-21-2008 05:09 PM

Sounds like you have it all figured out. And yes you are right.
The roofers all have issues with it because they do not understand it. I had a discussion with the rep from GAF about 3 years ago when this was in it's infancy so to speak. Closed cell foam has been around for 20 years. It was used in commercial first, then found it's way here to residential.
You need to find a new more experienced , roofer or fight with the one you have.
It's hard teachin old dogs new methods.
I have done roofs this way for 15 years, no issues yet.
Also look at

Educating them roofers is better than yellin at them, it gets the job done.

ajnabi 08-27-2008 07:23 PM


Thanks for your responses and the links. I have checked them out and feel much more confident now.

I have made the decision to use the closed cell foam. I also got a call from my roofer yesterday--he said he checked with a friend of his who had this done and there have been no problems... and this friend highly recommends it, so I think even the roofer is swayed now.

I feel better having feedback from those who have experience with this though.

So, thanks for your input!

PS. Sorry for my delayed reply... I had to leave town for a few days unexpectedly--sick relative.

inspectorD 08-28-2008 06:26 AM

No problem
We are happy to help.:)

I like it because it is the first step in better efficiency, glad to see you are spending the money for the good stuff. Tell others here of your progress, and a couple of pictures would be great. Closed cell spray foam is the new computer on the block in my opinion.:D

ajnabi 09-03-2008 09:38 AM

Be glad to tell of my progress and give some pics, however, due to some unforseen (which is of course forseen) circumstances, the project is being delayed until late October-early November. So stay tuned...

AtticCare 09-26-2008 01:11 PM

old dog new tricks. the guy with the highest bills in our neighborhood used that stuff......backfired, bad too for what you want to pay extra for the insulation, put that money into the efficiency of the ac. foam sounds great, but it will never pay for itself, even in cold climates, thick loose fill insulation in your attic is better bang for your buck!!!!!!!!!do it right?cmon lets just pour 2 feet of concrete all around it, do it right?? , specially if in certain conditions, like rafter installation it doesnt really work.... hence it is the least used insulation product in walls and attics and im sorry inspector but 20 years and your still not the first choice in new construction in the US, but more like the last, not insulting its quality just the ability to justify its cost........ yeah ok so i also am really worried about people sealing their attics......lumber can absorb and release moisture, but if say its humid and you seal your attic, your just asking for trouble...... if it becomes stagnant it will destroy your lumber,,,,,,and if you dont have a radiant barrier which can be a bad idea in the colder climates, but in a hot sunny climate whitout a radiant barrier and a few inches of airspace between it and your insulation your r value is useless, let me repeat the to the ones with r value woodies, pretty much USELESS. in the summer sun radiant heat is more far important than conductive. i am guessing this is a hot climate, you should explain your attic and location better, these educated responders didnt even ask your location, which is probably the most important factor, look at your responders, yall even have air conditioners up their, ive never met a contractor that would recommended it in the south or midwest, just the companies selling it and the inspectors in their wallets...........

inspectorD 09-26-2008 05:30 PM

I know , it's just one more opinion.:D
But this is a good thing, I just disagree with your responses.

IT all depends on where you live, the condition of the house and the building materials. I have given up on giving serious advice on a forum, if they are going to try something new, I encorage it.
The bottom line is, he asked for advice, I gave it ,just as you did.
What they really need is someone there at the house giving them unbiased advice.
Your blanket statement is just as bad. There are many places this does work, and pay for itself. :D

My house, I would go for for starters.
Oh yea, Welcome to the forum, glad to have some more experience around.:)

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