I am considering Superior Wall (precast) stem walls for a slab foundation system.
This is for a timber frame structure, and the 4’8″ SuperiorWall product is not thick enough at the sill to support 8×8 posts. So I’m considering putting a formed pier just inside the stem wall to support each post. Then a floating slab will be poured inside the stem wall boundaries and around each formed pier. The timber will rest on the piers, the stem wall will come up around the outer wall, the slab will not be structural support for anything (it’ll just be a floor). This approach will allow me to lift the outer wall above grade, while leaving the slab lower to maximize ceiling heights, and allowing perimiter insulation around the slab (which will contain hydronic PEX heating tubes).
Does this system make sense (appart from its cost)? What’s a good approach for setting up the pier forms so that the posts can rest just inside the outer stem wall? I’m thinking of a triangular pier with the wide side (base of triangle) against the frost wall.
Replies
My understanding is that Superior walls save on pouring footers and they are insulated.
But you are pouring piers anyway to support your timber frame. I think it will work, but for all that effort, and the fact that this is a timber frame house (as in a FINE house), I would be searching for an integrated foundation to keep everything bearing on the same solid system.
Since you were prepared to pay (15% more?) for Superior, why not consider ICFs (3% more?) or formed concrete with eps on the exterior? (just insulation costs) You would have a continuous footer for everything, insulation outside your thermal mass, and no worries that the timbers' foundation could settle separately from your floors.
In your application, it just seems you are wasting $$ on the "superior" walls. But again, it will "work".