The message
from "Barry Watts" contains these words:

Always a mine of useful information, I thought I'd ask the group if anyone
has successfully sealed of a garden shed to a concrete base.

I have an 8'x12' heavy duty shed being delivered/erected this week. There
is no floor to the shed, which will stand on a large level, concrete base.
I have a roll of 10" wide damp-course vinyl and thought I would stand the
upright walls onto this, then find a way of sealing the vinyl to the shed
and concrete.

Ideally the concrete base should be about 1" smaller than the shed's
dimensions, so that the shed frame sits on the base but the wood
panelling very slightly overhangs it. Rain can't accumulate on the base
and you don't need any DPC or sealant.

You also need to bolt a floorless shed onto the concrete base.

Janet.