I'm converting a garage to habitable space. It's bone-dry, but I'll
be adding a supplemental barrier on top of the slab.
describes a method of wood subfloor over foam over concrete instead of
the more common subfloor attched to sleepers over concrete.
I need to keep my whole floor (insulation, sub, carpet & pad) under 2"
so the ceiling height will be 7'6" when it's insulated. I could use
1" foam and 2x sleepers ripped to only 1", but what about skipping the
Dow's page on polystyrene and polyisocyanurate insulation doesn't
mention this application. My guess is that the tougher polyiso is a
good idea for crush-resistance.
There are UK and Australia web pages that mention this technique, but
the APA page is the only US one I've seen. Probably going to be hard
to get the inspector to OK this. It's also more work for the
subfloor- I can't get 4-edge tongue & groove, so I'll have to use
Would my idea of 1" sleepers with 1" insulation work or is the 1/2"
gap when using 2x sleepers required for some reason?
Thanks in advance!