Sealing bottom plate

I've got a roll of DPM about 20cm wide - was thinking of cutting a length, rolling it to make a long tube, held with a piece of tape, and squashing that between my bottom plates and the concrete slab to both make a seal and protect the plate from dampness coming up through the concrete.

Thoughts?
Good idea/Bad idea?

I was thinking of wrapping the wood in the DPM, but then I thought if water DID somehow get in, it would be trapped in there and the wood would rot for sure.

 

water might lie on the concrete

I think a better way is to build a 1-brick sleeper wall, and put the wooden joists on or across it, with DPC between them. Puddles are unlikely to rise high enough to get on top of the DPC, and the timber has reasonable ventilation.

Concrete bases usually get wet if they are not raised above surrounding ground level, or the shed does not overlap them, allowing rainfall to collect on the concrete.

 

How would water "lie on the concrete"
The only way the concrete can get wet is by soaking it up from underneath - I'm fairly sure that that will never result in pooling.

 

water can lie on the concrete in either of these cases:

 

Ah - sorry thought I'd put in my OP, this is a raised concrete pad that will be entirely covered by the shed.