On Jul 25, 12:06*pm, "DanG" wrote:
Tar impregnated sheathing ( black Celotex) will be just fine for
expansion joint. *Many places sell it pre cut.

As to your project:

It sounds like you do not have a floor now.

I'm not sure what you mean by washed concrete(.)

Me neither - I meant washed gravel. I'm reading "Renovating Old
Houses: Bringing New Life to Vintage Homes" and that's what was
recommended under the concrete and vapor barrier.

JP