small shed on larger concrete slab

[djtkach]

I'm building a 15x15' shed on a 15x20' concrete slab and am concerned about moisture coming in under the sill plate on the one wall which is adjacent to the 5' of open slab. I plan to use PT wood for the sill, with felt/membrane underneath, caulking on the exterior edge where the sill/membrane meet the concrete, but can only use flashing on 3 of the 4 sides.

The existing slab is level which increases the risk of standing/puddling water beside the shed, which may result in moisture wicking over time.

Suggestions please and thanks?

[MJ CORMIER]

What about a couple of tier of concrete cynder block.

[Fischer]

You could also platform frame it, and then put the shed up on skids or blocks. That way it wouldn't matter if water infiltrated, and you'll always have a dry floor. Also if it's up on skids, the slab would dry out. Extra cost would only be for the treated dimension lumber for the flooring and plywood.

[pushkins]

I'd go with the platform on skids, 4x4 or 6x6 skids then build your floor on that. It would mean a small ramp to get into the actual shed but better than water infiltration anyday. You can still bolt the shed down to the slab with some chemical anchor bolts.