I have a unfiinished basement that I am planning finish in the near future. I plan to air seal as well as insulate my rim joist and mud sill using close cell spray foam. I have an area that is cantilevered out from the house, a small area that extended the eat in space of the kitchen. I noticed that the area is very cold on my feet. I investigated and found that there is no insulation at all. My question is , can I spray foam that area and create enough of a thermal break. Also would It be a good idea to also block off the joist bays with rigged foam since the area is cantilevered over the ground.
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How far out does this extension project? How much clearance between the ground and the bottom of the cantilever?
It extends out about 3 feet. And is about 3 feet about grade.
The most important thing is to air-seal the area, to keep outside air out of the joist space. This may require laying on your back and caulking, or possibly spray foam could be used from the inside if access is sufficient.
I have the same type of set-up in my kitchen. I did block the joist bays with rigid foam and then dense packed cellulose in there. If you use spray foam, I wouldn't think you would need the rigid...mine is only there to hold the loose fill. I have read a couple of posts about houses catching fire due to the heat generated by the spray foam reaction. Be careful to build it up in small lifts.