# Basement Rim Joist Insulation in Tight Space



## Logan176 (Feb 18, 2016)

I'm almost done insulating my rim joists with 2" XPS foam boards in preparation for a basement renovation. There is a 12' span where the access is so tight that it's impossible to slide in the foam boards. 

I might be able to push in some batt insulation, but do you think I can use spray foam from a can?

If I slide the spray nozzle up from the bottom, I could probably reach about halfway up to fill the narrow cavity with foam. I could also drill small holes in the joist, just big enough to get the spray foam nozzle through, to take care of the top half of the cavity. 

Your thoughts?


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## jlhaslip (Dec 31, 2009)

The trouble I have had in the past includes needing the can to be upside down when spraying. Also, it takes several cans and will get expensive, even with the large containers.
Talk to a local Spray Foam guy and see what he would charge if you let him decide the schedule for a day when he has an opening while in your area.


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## Logan176 (Feb 18, 2016)

Unfortunately, I really don't have a lot of trust in spray foam that is mixed in a van in my driveway. I am still dealing with the aftermath of a poorly installed spray foam job in my attic. I understand the cans will be expensive, but at least I know they are all mixed the same way.


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## jlhaslip (Dec 31, 2009)

Too late for this project, but when I layout a subfloor, I watch for exactly this issue.
After having to deal with small joist spaces at the rim board a few times, I start to layout the joists except the last one or two and I lay those out from the opposite side, creating more room above the concrete for electrical and insulation issues. Still meets code as long as the spacing does not exceed the designed c/l's.


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## Bud9051 (Nov 11, 2015)

Not sure what that joist is, 2x10? but I suspect a 2x8 would do just fine. A reciprocating saw and a nasty blade would give you all the space you need. If you would feel guilty reducing the depth, then sister something along side of it. Being that close to the outside wall there really isn't a load concern.

Bud


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