Sprayed on Foam

1st time to run into this type of foam in an attic. Is anyone familiar with this product and would be willing to offer advise on the pros and cons of such a system. No ridge vent and soffits are cover with foam as well. Thanks in advance !



I am not but, seems like a hey I saw this on youtube, lets try this out.

Found this via NACHI search… Roy


It is considered by large the best. There is no venting. All venting must be closed off. There have been studies performed in Florida on the affects of roof shingles and heat. They found that no adverse effects. I will see if I can attach documentation.


Any roof warranty will be voided with this installation…

Please poet where you got that Information .

from what I read you could be wrong… Thanks… Roy

I’m pretty sure it was stated in the “inspecting asphalt shingle roofs” Nachi course.

Looks like you are correct spray foam can shorten the life of shingles …good. memory Thanks … Roy


Effect on Shingle Life

In general, shingles installed on unvented attic assemblies operate at a slightly higher temperature. This has impacts on the durability of roof assemblies. A 2 or 3 degree F. rise in average temperature is typical for asphalt shingles and a corresponding 10 degree F. rise in average temperature for sheathing (Parker & Sherwin, 1998; Rudd & Lstiburek, 1998; TenWode & Rose, 1999).
All other things being equal, applying the Arrhenius equation (Cash et.al, 2005), a 10 percent reduction in useful service life should be expected. This is comparable to the effect of the installation of radiant barriers. What is more significant to note is that the color of shingles and roof orientation have a more profound effect on the durability of shingles than the choice of venting or not venting (Rose, 1991) – double or triple the effect of venting/non venting.

Looks like some might give a warrantee Check with the manufacture …

Spray foam installed to the underside of your roof leaves no way to cool that side of the roof system. This may cause your shingles to overheat which may reduce their longevity and require you to replace them sooner. Check your shingle manufacturer’s warranties as some void or limit warranties or require special roof details when foam is used on the underside of the sheathing.

Can you imagine the mess when they peel back the shingles and have to replace a couple sheets of plywood? The most ideal installation for this IMO is a home with a metal roof. Have been in one that was built new with metal roof and spray foam and also an attic ventilation system because there is no ridge or soffit vents.


I see it in just about all the new homes I work in. Both tile and shingle roofs. Never seen it sprayed on the ceiling side though.

Looks like icyene open cell foam. Most manufactures will not void the shingle warrantee with this system. Actually the more they research it the less I hear people screaming the shingles are voided. The main concerns that need to inspected is whether or not they installed it properly. I usually pull out a core sample to look at the foam it needs to have tight tiny bubbles. If you get foam with large bubbles you reduce the R-value and can actually trap some moisture. It’s also a good idea to stick a moisture through to the decking. Pay attention to the texture of the foam as well, sometimes when they change out mixtures you’ll see almost a glazed looking foam, I’ve always made them remove that junk and respray it in that area. The improper mixture or lifting too much foam per spray can also cause it to shrink and break free of the rafters, trusses, ect which can allow air flow in behind the foam. This has to be removed, this will cause problems.

You have to realize the thermal boundary of the home is changed on renovations. It’s a good idea to remove the ceiling insulation so the attic is semi-conditioned. I always take a psychrometer with me to get the relative humidity in the attic. If it’s too high and the ceiling insulation is removed, you may have to advise them to install a supply and return to condition the attic and bring those levels down. When it’s done right, it’s the Cadillac of systems right now. I did a system for a big artist here and they now even keep incredibly expensive guitars in their attic.

Vented attics mainly reduce moisture, they reduce some heat at the back of the sheathing by the proper ventilation, but they increase radiant heat. When a radiant barrier is installed it redirects radiant heat with its emissivity. Now why in the world don’t people scream the shingles are voided when they see this system…just something to think about.

Kjones do you have any idea why they would put it on the ceiling? That’s not an accepted practice here, everything is done on the roof decking.

It’s all over SW FL - most new custom homes have it.

I’ve seen it a lot over the last 10 yrs.

Customers enjoy the lower a/c bills.

Between that insulation, peel and stick, and 8d ring shank nails, that’s one tuff cookie;-)

I forgot to add, I makes for for a difficult wind mitigation:-k

In the OP’s picture it looks like it is sprayed on the ceiling side also. I’m still just a carpenter not doing any inspections yet but I have never seen it there.

I don’t think all these custom builders around here would be using it if it voided the roof warranty. If I see the builder tomorrow where I’m working I will ask him.

This video will educate you all on the best practice to insulate an attic in any climate. Have fun watching Joe is the guru of building science and a blast to listen to. SimplyCLICK HERE

Wow, I really appreciate the information! Thank you everyone so much. Great video too.

Here’s a link that will bring you to a lot of info on spray foam and ventilation in attic spaces.


I agree