Dodgy concrete floor

[PeTe33]

HAving just ripped up 1 stinky bedroom carpet & underlay there appears to be the remains of damp patches on the concrete floor.

1970's built no insulation, just what seems to be about 3" or screed on a black membrane on-top of base.

Ra5ther than digging up entire ground floor and doing the job properly, would it be an option to put a laywer of polythene sheet (glued?) on top of screed before laying new underlay/carpet to reduce any damp that "may" be travelling upwards?

I am not convinced it is damp going up, more damp/condensation from when we first moved in and didn't realise there was a serious lack of ventilation until mould and significant condensation appeared on walls, furniture, clothes in cupboards etc etc.

Thoughts appreciated. Cheers

[Lobster]

I had the same problem, and received several replies - see

the end I'm afraid I just had new carpet and underlay fitted directly on to my 'dodgy floor' without further ado, so can't report back on the effectiveness of the solutions which several folk kindly suggested. But tbh, after a few weeks of exposure to the atmosphere the floor did improve a lot, and I think there were considerable condensation-type issues too (plus the place had been unoccupied for yonks). All seems fine after nearly a year but I don't particularly feel like lifting the carpet to check what's going on underneath!

David

[Stuart Noble]

That's what I'd try first, assuming it's flat and you've improved the heating and ventilation situation. Would you need to glue it?

[Chris Bacon]

Before taking action, ascertain whether or not you've a problem.

How do you know that?

There are various options.

[Pinot Grigio]

Got a similar problem with smelly concrete floors. They have been tested and are no longer damp. Whether there was a problem in the past or lack of ventilation we don't know. The thing is, once they get musty and smelly, they always seem to be that way. When we first moved in, and started renovations, we left a couple of rooms empty for about 6 months with plenty of fresh air over a summer. The floors seemed to be ok so we carpeted them with the underlay being put on top of (can't remember what it is called but it is black and a bit like greaseproof paper). The smell came back once it was covered.

We have wondered whether to tile over the concrete using some type of glue that would create a membrane. Otherwise I fear all the floors should be dug up and relayed over a new membrane. Two weeks holiday and the house smells pretty bad on our return.

[david lang]

Provided that it's just a smell and doesn't have an underlying cause, it's actually easy to completely remove a smell for good. Have a look at;

products are easily available at any janitorial supplier - check yellow pages - and they work!

Dave

[<me9]

Why do all these products contain a 'fragrance'. They get right up my nose. Is it because they don't work, and are disguising the smell with a stronger one?

[John Schmitt]

More importantly, what would he glue it with? Polythene has a very low surface energy, so it is difficult to get an adhesive to grip it convincingly. Lots of tackifiers in the formulation help but these make the adhesive liable to creeping In any case the nails in the gripper rods will quite probably suffice, especially if the edges are turned back under them.

John Schmitt

[John Cartmell]

They don't. But it's harder to find those without.

Possibly.

[meow2222]

bad idea. Trapping damp in an airgap tends to cause toxic black mould. On an uninsulated floor it might also trap condensation.

There are 2 possible fixes.

1. is to leave the floor bare for several weeks with good ventilation and warm weather, or if its real persistent a dehumidifier. In a lot of cases this is all thats needed.

1. If that doesnt work, painting the crete with watersealant will do it.

I really would not use a surface membrane. Health is too valuable.

NT

[PeTe33]

:¬)

Just got back to catch up on the thread. carpet and underlay was fitted yesterday on the old floor, so we'll just have to wait and see.

The old carpet did reek of dog/cat piss (Amonia stentch) and I know the previous owners had up to 6 dogs at one time so fingers crossed.

besides, if I do dig up the old floor(s) i'll be refitting with UFH to match upstairs, at least I have bought a little relaxation time away from major projects.

:¬)

[PeTe33]

It's been re-fitted with gripper strips, didn't have time to get the polythene down.

[PeTe33]

because the C/H pipes run under the concrete and bits of the edge have gone all crumbly.

I'm re-running pipes above floor level sometime very soon.