Far away this is the most popular option available.
Hot roof with spray foam.
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.
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.
Murmurs and hearsay about open cell spray foam insulation have been gaining traction for a while.
I ve been told by every insulation contractor that i would have to do a hot roof 2lb sprayfoam application.
But what thickness is most beneficial to my roof.
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.
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.
A hot roof is one where there is no ventilation required as the insulation is directly attached to the roof sheathing.
Hot roof with 2 lb.
Spray foam on a 3 12 pitch roof.
It rots roofs people have told me.
Attics typically have an insulated floor and have ventilation.
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.
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.
While some try to do this with fiberglass or cellulose.
I don t want the costs of applying additional foam to outweigh the benefits it will provide.
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.
If you don t want to use sips or nailbase read this article tolearn the four basic approaches to insulating unvented roof assemblies.
How hot roofs differ from traditional roofs.
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.
You pretty much have to destroy a roof assembly that has been insulated with spray foam if you want to remove any of the sheathing for example.
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.