Slab Sandwich
We have a basement with stone foundation and old cement floor (doubtful it has vapor barrier underneath) located in northwest Massachusetts. We just put in an interior perimeter drain with stone level with the current slab. Planning to cover with vapor barrier and 2″ of EPS or XPS, then pour new slab over that. I know with a brand new slab the vapor barrier should go between the insulation and the slab. With my slab sandwich, should insulation go on top of old slab, followed by vapor barrier and then slab. Or should vapor barrier go over old slab, then insulation and new slab. I’m planning to wrap the vapor barrier up the walls and tie into spray foam insulation so water will drain down and into the perimeter drain. Any feedback most welcome. Thanks.
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Stoltzberg,
The same logic applies as with a new slab. The poly should go over the insulation. Otherwise the bleed water from the concrete will pool under the foam and can take years to dry.