Very interesting for me to see the evolution of slabs.
In the mid 50's, around here, a lot of subdivision housing was ranchers on a slab. The slab didn't have much of a perimeter footing and probably lacked any rebar.
Lots of those houses still exist but I doubt that a single one of them has an unbroken and level slab. And they lacked any vapor barrier under them so rot in the bottom sill plate wasn't uncommon.
When I built my house much later I put in a perimeter that went much deeper, rebar and a central trench similar to yours that carried the load from the main load bearing wall.
But yours shows evolution in progress, a 3rd gen slab. Using sonotube at the trench intersections to create piers takes it to an even higher level.
Keep the build photos coming.
Ron
Threaded Mode
