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Discussion Starter · #1 ·
I am about to convert my garage to a living space. The floor is 3.5 in below the house floor level. I was going to pour in new concrete to match with the house level, plus I need to pour a curb where the garage door was. However I am thinking about insulating the slab as I live in zone 5. Can I put down 1 in ridged foam then pour concrete on that to level? Will that be strong ?

Thanks.
 

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That will give you a 2-1/2” slab ... i would not go any thinner, but since there won‘t be any heavy loads you should be ok. (Just don’t let my ex sister in law visit). You need to fasten the foam to the slab so it doesnt try to float up while waiting for the concrete to set.

Have you considered putting down 2x sleepers and fill in between them with rigid foam, then add a layer of 3/4” ply? What is the floor construction of the main house?
 

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Discussion Starter · #3 ·
The main house is on a slab, I did think about 2x4 framing, not sure which would be better long term.
 

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retired framer
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Does the garage have a concrete curb or will the floor be above the walls?
1" of foam is not much and insulating the floor will only help if you are heating the floor.
If you don't heat the floor the floor will be ground temp anyway.
 

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Discussion Starter · #5 ·
Yes the garage has a 3 in curb around the garage. This will become conditioned space after the conversion. The floor will not be not above the walls.
 

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retired framer
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this is the concrete curb I have in my garage, first photo is the door going to the living space, 3rd photo is the door going outside.
To do the foam you would have to level the concrete first.
When we do a walk out basement or a slab house they do insulate the outside edge with 3 choices. our frost depth is 18" so the foam goes down to the footing and when laid flat they just do 24"
The picture is the 3, we never see A and most times they do C.
1620231787025.png
 
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