Raised floor to slab on grade

[reviest54]

I have a client who has an existing wood raised floor foundation. The joists bear on top of the concrete stem wall. They want to do a portion of their addition as slab on grade. This means the concrete slab on grade will butt up right against the existing wood sill plate, joists, and floor sheathing.

Does anyone know a way of protecting these joists from moisture? Will flashing be enough?

Thank you.

 

[CELinOttawa]

Denso tape? Moisture break? Elastomeric/asphaltic strip?

In my opinion any traditional flashing material is likely to fail. I would use a combination of a hydrophobic elastomeric/tarry material PLUS a traditional flashing. Or potentially a plastic flashing...

The CCA and other pressure treatments tend to each flashing metals. It is a problem we are seeing more and more, particularly in low rise condominium developments.

 

[reviest54]

Thanks CEL. The elastomeric combined with traditional flashing is what the architect is recommending.

 

[XR250]

Maybe stainless flashing. Aluminum and galvanized will fail. Even the vinyl flashing i have seen deteriorate.

 

[reviest54]

Thanks XR, I'll look into it.