concrete floor sealing

Consider the patch of concrete floor shown at

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It's on the ground floor (which is below ground level at the front) of a Victorian house. The dark brown and blue patches are bits of underlay rubber that have stuck to the floor.

Am I right in thinking that the thin rubbery surface on most of the floor is intended to seal against damp? And that its absence in places would explain a patch of mould on the carpet? It was under a chest of drawers.

The exposed parts don't *feel* damp.

-- Richard

Reply to
Richard Tobin
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you can check if there is any damp by putting down a sheet of newspaper and then polythene on top. weight it down and leave for a few days. if the floor is dry, the paper will stay crisp. if it is limp or wet then you don't have adequate damp proofing.

Reply to
Bob Minchin

On Thursday 24 October 2013 14:53 Richard Tobin wrote in uk.d-i-y:

No - I think that was solvent adhesive used at some point to stick vinyl or lino down. I had the same.

That's a poor metric - take a 50cm square sheet of plastic, ideally clear and tape it down over the test area.

Leave for 2-3 days - damp will be very obvious as condensation underside the plastic.

What covering are you planning on laying?

Reply to
Tim Watts

There certainly seems to be some amount of damp - elsewhere on the lower floor paint has peeled off the cement skirting, and where a board was left leaning against a wall for months the surface (I think it's painted wallpaper) has come loose.

That seems very likely.

The question is, what to do? The dampness has not been enough to cause any mould before, at least in the last 15 years. Should I just turn up the heating and try to improve ventilation?

Do you agree with the other poster that the rubbery coating is old glue rather than a seal?

-- Richard

Reply to
Richard Tobin

I think it's my preferred course too...

Thanks to you and all the others who commented.

-- Richard

Reply to
Richard Tobin

I'm not sure if the stuff sold as garage floor paint has sealing properties - I'd expect that it would, simply because there are surely lots of garages out there with concrete floors that aren't insulated and have no DPM.

There's also the latex basement wall paint which is designed to seal cracks, but IME it's crap even on walls, so I don't know how well it would work on a floor (with some sort of carpeting or whatnot over the top to reduce damage, obviously).

Oh, they do epoxy garage floor covering stuff this side of the Pond, too

- IIRC it's two cans that you mix prior to application, along with a bag of flakes to make it less slippery to walk on. It's quite expensive (about 3x the cost of "garage floor paint" cans) - however, I don't think it's been available in DIY stores for that long, so maybe it's one of those things that will come down in price in a year or two.

cheers

Jules

Reply to
Jules Richardson

On Saturday 26 October 2013 21:01 Jules Richardson wrote in uk.d-i-y:

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That's a "proper" epoxy DPM - I've used it - it works and is easy to apply (but you have to be quick which is not difficult if you get everything prepped, clear and ready beforehand.

Best applied with a roller on a long pole so you can apply whilst standing.

Reply to
Tim Watts

Just looks like flooring cover adhesive to me Anti-damp treatements are either bitumen form providing a rubber barrier, or a 'soaked in' clear surface treatemnet.

Reply to
Rick Hughes

Missed one - you can also apply an epoxy DPM as I did on one room with a shot damp proof layer. Personally I'd rate the epoxy as the best. See f-ball.co.uk for various products and guide notes.

Reply to
Tim Watts

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