Damp-proof membrane for shed: How should it be edged?

[livinginhope]

Hi all, a while back I had a wooden garden log cabin put up. It has a concrete foundation, then a plastic sheet as DPM, then the actual log cabin on top of that. I'm about to paint weather-proofing on the wood, and discovered that the builder has left the DPM in different positions on different sides of the cabin - as shown in the two attached pictures: At the front, the plastic simply extends in beyond the cabin walls and has been roughly cut. At the back, the plastic has been hooked up and nailed to the cabin - which looks marginally better, but makes it difficult to paint down to the cabin base.

Which arrangement is correct? How should the DPM be left so it provides full protection without being unsightly? And I'd like to pull the nails out at the back so I can paint the weather-proofing on the wood behind where the DPM is attached. Is there any reason I shouldn't do that?

 

[ericmark]

My shed is on plastic pallets, how long it will last I don't know, but at least any water can drain away, I question why a concrete base? Inside my shed, there is a wooden floor, which for storing things is fine, but to bolt a lathe to the floor I can see a problem.