Lets Try This Again: A Well Insulated Slab

Time was ticking and we ran out of 2" type II EPS.  Luckily our local building suppliers carry a small supply of 2" 2'x8' Foundation Plus.   The next morning we finished up placing the foam.  Pipe and conduit penetrations in the foam were cut slightly oversized to allow some room for aligning the foam pieces together.  After the foam was laid, we spray foamed around the pipes (Photo 1-1).  This serves 2 purposes:  The first is to insulate, the second is to stabilize the pipes during the cement pour.

On to the next task:  Vapour barrier, air sealing, and rebar!


  1. Did you go with 10 in insulation, and is your garage insulated to the same standard

    1. Hi Winston, it's been a while! Hope all is well. There is 10" of type 2 eps under the house slab with the exception of the thickened rebar reinforced section in the middle. That section has 6" of type 3. I wanted a well insulated garage so we went with 4" under the garage slab. There is also a check poured into the foundation wall at the top so foam could be added in order to isolate the garage slab from the foundation walls. The garage walls will be insulated to r20 with batt but there is 3" of eps to the outside. I think the effective r value works out to be about 28 but I would have to calculate to confirm.




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