We are planning a new build with a walkout basement. The ceiling height is currently 9′. I am thinking that I might want to top the slab with insulation and then Advantec as seen on some of Matt Risenger’s videos. Problem is that is going to take away from the 9′ ceilings. I was wondering if we could recess the slab so when the insulation and Advantec is added it will be level with foundation walls? What issues might this cause?
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Replies
Just make your foundation walls taller.
The foundation for the walls needs to sit on undisturbed or properly compacted soil.
Trying to make the slab or slab base lower than the foundation needs to be considered with the long term impact on where the foundation rests.
It might make more sense to insulate under the slab.
We plan on insulating under the slab too. The insulation on the top of the slab is give the floor some extra insulation but also give it more give so it is easier on the knees.
As I said previously, make the walls taller. If they're already built, then it's time for some compromises. In any case, the bottom of the insulation under your floor slab should be no lower than the bottom of the footing under the foundation walls.