"Phil L" wrote

underfloor DPM is normally overlapped by 500mm to keep damp out of the
concrete.
It seems like someone has taken up a strip of concrete where the floor
meets the wall, possibly to make a channel for the pipes, and because the
inner block is easier to remove than concrete, they've taken this out and
then not joined the DPM properly to the existing underfloor DPM.

To do it properly, they obviously wouldn't take up 500mm of concrete in
order to get the required overlap, so it should have been overlapped as
much as possible, say about 100 - 150mm and glued, either with silicone or
some other waterproof sealant.

this is what will need to be done now if it's ever to be dry again.

And if the pipes are copper, they will need to be wrapped in PVC tape
prior to concreting.

Phil

Thanks for all your help with this.
Knowing how things should be will help when the insurance contractor comes
back - particularly if he starts spinning yarns/spouting the BS.

Phil