Residential Slab Foundation

[TRAK.Structural]

I'm reviewing some drawings by others (see below) and wondering if this type of detail for a slab foundation is common for residential construction. More often I've seen a monolithic turndown at perimeter walls, i.e. no construction joint/separation between the thickened edge foundation and the interior slab. Which way do you see this detail most often? Are there pros/cons between this approach and the monolithic approach?

 

[kissymoose]

We haven't used it, but it's becoming more common for energy conservation. The insulation provides a thermal break between the interior slab and exterior exposed foundation. I still haven't seen any sort of quantitative check/test/reasoning for it, just inclusion due to the idea "thermal break good."

Pros: Decreased thermal transfer from interior slab to exterior exposed foundation, of unknown quantity
Cons: Harder to build/easier to mess something up