Damp solid floor

Hi

When I pulled up the living room carpet, it was extremely musty and a bit damp beneath, and I found the remnants of what looks like some form of old DPC layer between the solid concrete floor and the underlay - it was black, bitumeny, very old and disitegrating; looks a bit like thin roofing felt.

Any suggestions for treating said floor? I know there's certainly no DPC membrane below it, as I once had to dig a hole for installation of water/electricity supply (and digging up and replacing the whole ground floor is *not* an option!!). What would the roofing-felt-like layer have been? Worth trying to replace it? Or should I try painting the floor with bitumen-based paint? Or something else?

Thanks David

Reply to
Lobster
Loading thread data ...

Hi David, try this....

formatting link
've used their products when 'tanking' a cellar, and they *do* work brilliantly.

Tim

Reply to
Tim Nicholson

Hi David - remember the dampness is under slight pressure enough to lift lightweight membranes, so I don't think paint would do the job. And I don't think roofing felt would be durable enough and the dampness would probably get through the lapped joints. That's why replacing the floor incorporating a damp-proof membrane under the slab is the preferred method. But there are other options. The traditional way of dealing with damp floors was to lay impervious quarry tiles or wood blocks in hot pitch. In the 1930's it was quite common to lay coloured flooring grade asphalt direct on the concrete slab, and more latterly tanking, using multiple coats of screed with Sika waterproof additive, has become popular. With all these ideas the moisture has nowhere to go and frequently can spread into adjoining walls unless there's a good dpc at the right level.

Another option is a ventilated plastic egg-crate membrane like Newtonite System

500 under a new screed, which allows the floor to breathe. This material is for quite serious situations though and I see they do another product called Newton Slimline which is laid over the screed. This looks like it could be suitable for your situation. I don't have any experience of this product myself.
formatting link
Reply to
Peter Taylor

Could it be old building paper or similar?

It's possible that there is a bitumenous DPC in the concrete which you've missed. Are you sure the damp is coming from below and not elsewhere? You could apply a bitumen emulsion, but it's not resistant to wear. How damp is "a bit damp"?

Reply to
Jerry Built

Paint is just glue, with pigment in.

If the paint is adhered well to the concrete, then it can work well. Getting it to stick is another matter.

Reply to
Ian Stirling

Thanks all - this certainly seems worth looking into; many thanks! David

Reply to
Lobster

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.