Slab floor addition, add insulation/subfloor, not much height
I’ve been researching so much, and things are becoming more muddy than clear. Maybe someone can help me. I’ll try to keep it simple.
– live in Western Washington
– adding one room addition on slab. Exterior done, now focusing on interior (approx 300 sq ft)
– slab (mono pour) has gravel/6 mil underneath and R-10 2″ EPS on outside
– slab poured last summer and closed in all winter, so good and dry
We have about 1-1/4″ allowance to add to floor before we run into height transition issues
1) is it worth adding 1/2″ rigid foam and 3/4″ subfloor for additional warmth and “cushion”
2) I’m considering layering like this: slab, polyiso, 3/4″ TG osb or ply, with 8-10 tapcons per board.
3) do I need 6mil under rigid foam?
4) 1/2″ Polyiso is avail at box store. Could prob get 1/2″ xps at lumber yard. Is one recommended over the other?
Any tips or recommendations? I’m a DYI gal who loves home projects. Built attached garage a few years ago, and small studio in backyard. Now into this “big” project and want to do it right, and keep the inspectors happy 🙂
THANK YOU for any expertise you can offer. I really appreciate it.
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