[VilGeorge]

Has anyone put foam, either high or low density, on the interior side of their roof? I put the low density foam on my roof in Georgia and it made a tremendous difference. The blown in insulation was removed and the vents were sealed. As a result the attic temp was no warmer than 10 degrees above the house interior temperature. My power bill dropped as well. Every time I try to search this subject all I get is info on garage or lanai insulation!!

[TMHwestford]

Originally Posted by VilGeorge

Has anyone put foam, either high or low density, on the interior side of their roof? I put the low density foam on my roof in Georgia and it made a tremendous difference. The blown in insulation was removed and the vents were sealed. As a result the attic temp was no warmer than 10 degrees above the house interior temperature. My power bill dropped as well. Every time I try to search this subject all I get is info on garage or lanai insulation!!

Our CYV here in TV is built this way, I'm glad to hear you saved money when you made the switch I've always been concerned that it was costing us money because we have to condition the attic to some extent.

[Ruger2506]

For the life of me I will never understand why they are reluctant to foam and when they use spray foam they use open cell instead of closed cell. If you ask me they should be using closed cell spray foam on all these houses.

Another option. My parents had Radiant Barrier Foil installed in their attic here in The Villages and it made a huge difference neither were an option when we built out home in Middleton. Not during the build anyhow.

[kkingston57]

Originally Posted by VilGeorge

Has anyone put foam, either high or low density, on the interior side of their roof? I put the low density foam on my roof in Georgia and it made a tremendous difference. The blown in insulation was removed and the vents were sealed. As a result the attic temp was no warmer than 10 degrees above the house interior temperature. My power bill dropped as well. Every time I try to search this subject all I get is info on garage or lanai insulation!!

Be careful especially if you have an asphalt shingle roof. Sun heats up the roof and foam insulation will create a lot more heat between the roof and the foam insulation and could cause damage to your roof. Also if you have a small roof leak you will never know it since the water can not go through the foam. Check with a roofer. Friend in S. Florida had it and it worked great but problems I cited MIGHT occur later

[Ruger2506]

Originally Posted by kkingston57

Be careful especially if you have an asphalt shingle roof. Sun heats up the roof and foam insulation will create a lot more heat between the roof and the foam insulation and could cause damage to your roof. Also if you have a small roof leak you will never know it since the water can not go through the foam. Check with a roofer. Friend in S. Florida had it and it worked great but problems I cited MIGHT occur later

Both the scenarios you describe occur when foam is installed incorrectly.

It shouldn't touch the sheeting. There should be baffles in place to allow air movement between the foam and sheeting so the ridge cap (ridge vent) and soffit can move air as intended.

[villagetinker]

I agree with above, I have seen articles that indicate you should never spray the foam directly on the roof sheathing, so if you are considering this option have a detailed discussion with the insulation company as to exactly how this is done and applied. Check on the flammability of the product being used. Finally, ask one of the home inspectors about this option, I like Frank D'angelo.

[MarshBendLover]

I have considered it, but moisture by a failed installer is all it takes to cause issues. Resale can be devastating if they even think there is a moisture issue. Not to mention overheating shingles. Flammability is an issue to cut costs. It's funny, I recently researched it just last week for the garage attic. Still undecided. Once you do it, you can technically utilize the attic if the truss system can handle the weight. Will be following this thread. I may need to reach out to Tinker's guy.

[rsmurano]

Misinformation on a couple of threads. I built a custom home in Georgia and I used this closed cell foam in my attic and walls and my attic (5500 sq ft home) was always 70 degrees in the attic.
The 2 posts above that had misinformation were the ones that said you still needed a ridge vent and baffle. NOT TRUE! The foam was sprayed directly onto the plywood in the attic and in each cavity between the studs in the walls. I know, I watched them spray it.
I had no vents at all, it was a completely sealed attic: no ridge vents, no soffit vents, no can vents, no builders gap. I also had a friend that put this in his exiting home and the 1st thing they did was to seal his whole attic: take out all the vents.
There are 2 types of foam and there is a big difference in price, the closed cell being the most expensive. And yes, if you develop a leak, you won’t know it for a long time if it’s closed cell because it’s so dense, it will have to soak thru all this foam then onto your drywall in the ceiling before noticing you got a leak.
If I built a new home, I would definitely put it in because it’s too big of an expense sealing all the vents/soffits before spraying

[Alarmed]

I have a metal roof but that makes no difference. They are doing my metal car storage building next week with closed cell foam for additional overall strength of the building plus it is water proof. The week after they are doing my house attic with open cell foam after sucking out the old blown in insulation.

I recommend you call Jeff at Suncoast for a no pressure estimate and an education of the product. 352-239-4628

[JRcorvette]

Originally Posted by rsmurano

Misinformation on a couple of threads. I built a custom home in Georgia and I used this closed cell foam in my attic and walls and my attic (5500 sq ft home) was always 70 degrees in the attic.
The 2 posts above that had misinformation were the ones that said you still needed a ridge vent and baffle. NOT TRUE! The foam was sprayed directly onto the plywood in the attic and in each cavity between the studs in the walls. I know, I watched them spray it.
I had no vents at all, it was a completely sealed attic: no ridge vents, no soffit vents, no can vents, no builders gap. I also had a friend that put this in his exiting home and the 1st thing they did was to seal his whole attic: take out all the vents.
There are 2 types of foam and there is a big difference in price, the closed cell being the most expensive. And yes, if you develop a leak, you won’t know it for a long time if it’s closed cell because it’s so dense, it will have to soak thru all this foam then onto your drywall in the ceiling before noticing you got a leak.
If I built a new home, I would definitely put it in because it’s too big of an expense sealing all the vents/soffits before spraying

I agree. We have had foam insulation in several homes and it is by far the Best insulation you can get. The only thing is you need to make sure the person doing it knows what they are doing. I am not sure close cell is worth the extra money unless you plan on staying in that house for a long time. I have been considering doing my garage with foam. It gets so hot in there I could cook a pizza on the hood of my car!

[jrref]

I feel this is a very bad idea. As others have said, if you get a roof leak you won't see it for a while and the wood sheathing will rot. You have to ask yourself, am I going to use a conditioned attic? If not, your living space shouldn't be that much different than a well ventillated and insulated attic shouldn't be that much difference than a spray foamed attic.

[Ruger2506]

Originally Posted by rsmurano

Misinformation on a couple of threads. I built a custom home in Georgia and I used this closed cell foam in my attic and walls and my attic (5500 sq ft home) was always 70 degrees in the attic.
The 2 posts above that had misinformation were the ones that said you still needed a ridge vent and baffle. NOT TRUE! The foam was sprayed directly onto the plywood in the attic and in each cavity between the studs in the walls. I know, I watched them spray it.
I had no vents at all, it was a completely sealed attic: no ridge vents, no soffit vents, no can vents, no builders gap. I also had a friend that put this in his exiting home and the 1st thing they did was to seal his whole attic: take out all the vents.
There are 2 types of foam and there is a big difference in price, the closed cell being the most expensive. And yes, if you develop a leak, you won’t know it for a long time if it’s closed cell because it’s so dense, it will have to soak thru all this foam then onto your drywall in the ceiling before noticing you got a leak.
If I built a new home, I would definitely put it in because it’s too big of an expense sealing all the vents/soffits before spraying

You are right. Thinking back to the last garage we had done. They direct sprayed to the sheeting on the roof. The house was done a few years prior and that's when we had to install baffles.

[rsmurano]

Bad idea? I would do this in a heartbeat if I was building a new home and I had the option. Not sure if I would use closed cell again or open cell.
As for not making a difference, there is a huge difference when an attic is 150 degrees and 70 degrees. Also, I did my walls too and you have so much air leakage in your walls unless you have a log or timber frame home with 10”-12” logs. My buddy that converted his attic to closed cell from blown in insulation told me he cut his cooling expense each month by almost 1/2.
Closed cell is almost 2x more expensive to put in. The only thing about here in Florida is that I hear they replace the sheathing when they do a new roof. If that’s true I would spray closed or open cell insulation on a roof that will get replaced every 15 years. Maybe the roof would last longer with the open/closed insulation because you wouldn’t have the 150 degree heat under the sheathing

[cherylncliff]

Originally Posted by VilGeorge

Has anyone put foam, either high or low density, on the interior side of their roof? I put the low density foam on my roof in Georgia and it made a tremendous difference. The blown in insulation was removed and the vents were sealed. As a result the attic temp was no warmer than 10 degrees above the house interior temperature. My power bill dropped as well. Every time I try to search this subject all I get is info on garage or lanai insulation!!

We had a free SECO energy audit when we built in 2011. The inspector recommended against the metal foil for several reasons including damage to roof shingles and really long payback.

[CarlR33]

Originally Posted by jrref

I feel this is a very bad idea. As others have said, if you get a roof leak you won't see it for a while and the wood sheathing will rot. You have to ask yourself, am I going to use a conditioned attic? If not, your living space shouldn't be that much different than a well ventillated and insulated attic shouldn't be that much difference than a spray foamed attic.

So how do you see a leak better with regular insulation vs. not seeing it with foam? No one is going to the attic looking for leaks until a ceiling in a room becomes wet with both systems?