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Damp on concrete floor after removing old lino

Posted: Sat Nov 07, 2020 7:34 pm
by FirstTimeHomeOwner
First post here, so please be kind :)

I have just taken up lino flooring to replace it with laminate, and have hit a big problem. The concrete floor under is very, very damp, leaving mouldy patches in places on the lino. It's not the whole floor, just down one wall, going about 40cm into the room.

Any ideas what may be causing this in the one place?

It's a terrace house, the wall is joining onto my neighbours. I had to have damp proofing done before I moved in a year ago - the wall itself is dry, I have wallpaper on it and that is completely dry and not peeling off (had that issue in another room so waiting for the guy to come back to sort it - it's on the opposite wall so won't be linked).

Bits of the concrete floor had come up where the old carpet gripper had been ripped up, it's only a thin concrete layer then more like a sandy material. I, well, cheated at that point and fixed it with grout... Could it be something as simple as the grout not being strong enough for that purpose, moisture coming up from the floor, and then soaking through? If so, removing that and replacing with concrete would be an easy fix (I'm a lot more confident with these things than I was a year ago - I'd go straight for the concrete now, rather than trying to bodge it!)

The issue does not carry on into the next room

Really hoping that this is a simple fix and doesn't end up costing me more money... For now, tomorrow will be spent sorting my spare room so I can go put my work computer back up there, not sure the front room where I have been working will be suitable for working in at the moment.

Re: Damp on concrete floor after removing old lino

Posted: Sun Nov 08, 2020 10:11 pm
by stoneyboy
Hi firsttimehoneowner
The most obvious cause it that there is no Dpm in the floor at that edge or the dpc you have had installed is above floor level. If your central heating pipes run under the floor the presence of a sandy material may be a cover for heating pipes (which are leaking).
Regards S