I do believe it still works as described here: Building Pieces + Temperature Resistances:

Edit: I have not tried whether stacking foundations changes anything in this regards. May try for science later.

Edit2: Tltr.
The building material only really matters in case of extreme temperatures.
If you build in a hot area with cold resistance pieces, you will have the same body temperature.
If you build in a hot area with heat resistance pieces, you will have a lower body temperature.
If you build in a cold area with heat resistance pieces, you will have the same body temperature.
If you build in a cold area with cold resistance pieces, you will have a higher body temperature.