thescullster wrote:
Phil

Thanks for taking to time to read and respond.

Yes, as the patio door was not an original feature, the strip above
the inner blocks was added with the patio door.

I haven't excavated serious amount of this floor strip out yet because
insurance company is involved and maybe I can get them to do it.
From the little I can see though, some of the dpm is damaged where it
wraps over the top edge of the inner block and damp is concentrated
in that area .

The inner block should come up to floor level - if someone in the past has
broken the top edge of this block off for some reason, it's almost certainly
rising damp coming up from below ground via the blocks and a DPM isn't going
to seal properly on a broken block.


So the only accessible bit of dpm at this point is the top broken edge
emerging from between the floor slab and the inner block. My
question is: how do I attach dpm to this top edge to lay over the
inner block?
Also there is sand above the dpm rather than below it from what I can
see.
Hope all this makes more sense.

Phil

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 L
RSRL Tipster Of The Year 2008