Insulate crawlspace

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iknowaguy
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Insulate crawlspace

Post by iknowaguy » Thu Oct 31, 2019 2:02 pm

I have a ranch home with a basement. Originally the house had an attached garage but had been converted to a living space by spanning joists across the garage floor and converting the area above to a conditioned space. Leaving about an 18" crawl space underneath the living space with a concrete floor. The floor above gets pretty cold in the winter. There is currently insulation in the rim joists ends but that is it. I would like to get the living space above a bit warmer. I have access to the crawl space at the bottom of my stairs for the basement which is adjacent to this room. The crawl space walls are all above grade on the outside. My initial thought is to apply rigid foam tight to the walls and rigid foam in the rim joist ends with spray foam around the edges but there are quite a few obstructions such as ductwork conduit. So I may just spray foam.

1. Am I ok to just spray foam the rim joist and ends and bring it down the concrete wall as well?
2. Should I do something to the concrete floor in the crawl?
3. Should anything be applied to the underside of the joists, maybe regular insulation with poly stapled to the bottom of the joists?

I am attaching a crude diagram for a visual.
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crawl.png
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Shannon
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Re: Insulate crawlspace

Post by Shannon » Thu Oct 31, 2019 5:02 pm

Well in my opinion I would apply rigid foam agains the walls and then sprayfoam the rim joist ends and right down onto the edge of the rigid foam. This would be the most cost effective. If you have access I would also heat the crawl space area. It does not need to be room temp. just get it above freezing so the air is warmer and the floor above will be warmer. Running a duct from the existing furnace into that area will work. I would run it out kinda half way across the crawl space area. I would see how this preforms before you spend more money insulating the floor. You will likely find a difference for sure.
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iknowaguy
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Joined: Wed Oct 30, 2019 3:36 pm

Re: Insulate crawlspace

Post by iknowaguy » Fri Nov 01, 2019 1:54 pm

Do you recommend leaving the floor alone?

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Shannon
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Re: Insulate crawlspace

Post by Shannon » Fri Nov 01, 2019 5:07 pm

Personally the floor Of the actual crawl space is not likely adding to the cold much and not worth the $ to insulate IMO. At least I would try these other things first and see what happens before you spend $$ you may not need to. If you wanna are any this year I would do the outer 4’ perimeter against exterior grade beams that will be the coldest areas since this floor is above or at ground level.
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