Hot Roof With Spray Foam

Spray foam on a 3 12 pitch roof.

Hot roof with spray foam.

What s the recommended thickness of a spray foam roof. How hot roofs differ from traditional roofs. Far away this is the most popular option available. Don t let that ominous hot roof label fool you it s one of the best options for your roof as it will save you from costly repairs from damaged caused by ice dams.

By simple averages and 24 rafter spacing 8 of closed cell spray foam and 2x10 rafters you get about r33 for the assembly about r32 with 16 rafter spacing. 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. Attics typically have an insulated floor and have ventilation. It rots roofs people have told me.

I don t want the costs of applying additional foam to outweigh the benefits it will provide. Unvented roof assemblies should be insulated either with air impermeable insulation rigid foam or spray polyurethane foam or with a combination of foam and air permeable insulation. You may be wondering spray foam roofs get spray applied meaning they can be a inch 2 inches or 10 inches or really any thickness a spray foam applicator feels like doing. Spray foam under the roof this approach involves installing closed cell spray foam directly under the roof surface right down to the junction of the ceiling and exterior walls.

If you don t want to use sips or nailbase read this article tolearn the four basic approaches to insulating unvented roof assemblies. It s ugly it s expensive to remedy and it s potentially avoidable if the roof can be ventilated. This eliminates roof venting and creates what is called a hot roof where the attic space becomes part of the conditioned heated and cooled house space. The term hot roof comes in because the spray foam insulation is being affixed directly to the roof sheathing which removes the need for ventilation.

If you d like to learn more about using spray foam to create an unvented attic system for your home give us a call at 866 900 3626 or fill out the form on our website to schedule a free in home estimate. While some try to do this with fiberglass or cellulose. I have read articles about hot roof spray foam failures and seen these failures in person with consequences including rotten roof sheathing mold and in some cases extensive condensation damage to drywall. Canada01 posted in green building techniques on january 31 2018 10 36am i m in toronto and i ve built a house with a roof pitch of 3 12.

Hot roof with 2 lb. A hot roof is one where there is no ventilation required as the insulation is directly attached to the roof sheathing. Murmurs and hearsay about open cell spray foam insulation have been gaining traction for a while.