The wall dividing my kitchen and extension is damp. It's the only wall
in the house that has a concrete floor either side of it and the only
one with significant dampness (even though it's been dpc'ed and lime
plastered - no guarantee, done by a plasterer).

My initial feeling is to remove a couple of inches of the concrete
floor next to the wall and install some membrane but I have no idea
whether this is feasible or whether it's just a daft idea.

Can anyone help? I'm 95% sure that the concrete floors are drawing
dampness to the wall.

Thanks, Ed.