Sloped roof with cavity spray foam insulation sprayed on underside of roof deck and covered with a sprayed on thermal or ignition barrier coating over the spray polyurethane foam insulation if necessary based on the material properties of the spray polyurethane foam or as required by code source.
Spray foam roof deck.
But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used.
The concern here is with an unvented attic where insulation is installed directly under the roof deck the shingles may degrade rapidly due to the increased heat caused by the insulation.
Other considerations to get the best performance out of spray foam insulation you must cover the roof rafters and surrounding areas as thoroughly as possible.
I m assuming that you are installing the spray polyurethane foam to the underside of the roof deck.
Now more than ever architects are beginning to use materials and design features more common in commercial construction when building domestic homes so spray foam has a.
Proper drainage prevents ponding water deck deflection and protects the roof from leaks and premature failures.
Even small gaps can allow the passage of.
Despite the advantages of using spray foam under the roof deck there are some potential risks.
Foam lok is spray applied to the roof s surface making it possible to vary the thickness of foam and ensure proper drainage.
Not long ago someone even told me that in florida roofing companies won t let their workers go up on roofs with open cell spray foam because the roofs are so spongy the guys fall right through.
If you use open cell spray foam on your roof rafters you should cover the finished application with a paint or sealant that retards water vapor.
While spf offers decent r value when precisely applied its thermal resistance is only as good as the worker controlling the spray foam mix.
This results in extended life span.
It rots roofs people have told me.
This concern is over exaggerated.
The primary risks are rainwater leaks condensation from diffusion air leakage and built in construction moisture.
Murmurs and hearsay about open cell spray foam insulation have been gaining traction for a while.
Spray foam roofing has become a particularly popular solution in the commercial roofing industry but that doesn t mean it can t be right for your residential roof.