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Insulating above slab

jbrys | Posted in General Questions on


I am currently adding R10 SilvrBoard – a high compression version above the slab. It will have two inches and then 2 layers of 1/2inch OSB on top of that. 

Structural walls will go to cement. Non-load bearing will sit above – correct?

Question is about drain holes and what not in the mechanical room – do we just continue with placing down in the mechanical room and extend those up? 

Thanks in advance,


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  1. Expert Member
    Michael Maines | | #1

    Jarryd, as long as the concrete slab is flat, you can frame partition walls (non-load-bearing) on top of the foam. Higher density foam is even ok under load-bearing walls.

    Yes, just extend your utility penetrations up far enough to make them accessible, and cut the foam around them.

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