[dbhansen]

Is it necessary to put plastic sheeting under a foundation slab that sits on top of a wall going below the frost line? See attached pic. Is the point of the plastic to keep water from wicking INTO the slab, or the other way around? I expect the ground will stay dry under my foundation. Can I just pour the concrete right onto a 4-6" layer of stone, or would plastic help it cure? I would just use the plastic regardless, but a roll of 6 mil sheeting costs $24 at Lowes, and that can buy a lot of flour!

But now that I look at my own picture, I see that that half-height row of blocks (just under the top row) will let water in....D'oh!! Live and learn. Maybe I do need to put some plastic and rigid insulation under there after all (I shoulda' gone with the solid blocks!). Suggestions appreciated.

FOLLOW-UP: I confirmed with the block manufacturer that this foundation should be perfectly fine as long as I fill the holes in the half-hi block with mortar to keep the dirt and water out. Stupid rookie mistake on my part; I'll be sure to use a solid block on my next oven!


Daren