Damp floors

[tjhever]

I live in a mid-terrace house (built 1892) and have taken up the carpets downstairs as I'm wanting to replace them. The front living room has a wooden floor and the back has a concrete floor. I noticed that both floors are damp to touch underneath the underlay, there is no damp in the walls -is this normal?!? I want to lay a wooden floor but am worried that this is a mistake if the floors are damp. The wooden floor is very springy in one place and drops by an inch in the corner, not sure if this is related to the dampness.
Any ideas about who to get in builder? Flooring company? or if i should be worried at all about it
Cheers!

 

[Geoffrey]

How long have the carpets been up for? If you've just lifted them I'd leave it a week or so and just see what happens. A little bit of give in the floorboards is not uncommon anyway.

 

[worms]

While spring in the floors might be OK, this sounds very similar to a floor we had where the joist end was rotten in the corner of the room. Is there any way to lift one of the boards and look underneath?

 

[tjhever]

The carpet was lifted last week in the room with the concrete floor, I haven't had the courage yet to remove it from the wooden floor! I'll lift in the next couple of days and have a look underneath at the joists. Thanks for your replies and I'll keep you posted!

 

[tjhever]

Geoffrey - if the floor dries out is that ok? would the dampness not just come back once I put a new covering on the floor?

 

[Geoffrey]

Well it depends whats causing the damp I guess. In my limited experience I've found it takes a while to eliminate the various possible causes. Was the carpet wet when you lifted it or has the damp appeared since? It could be condensation if the concrete is cold - are there any pipes running through the concrete to radiators or taps that may have corroded. It would be unusual for a concrete floor (depending on age) not to have a dpc. Depending on the floor you want the supplier would probably recommend a membrane on top of the concrete anyway in an old house. Of course if you do have a damp problem this could relocate it to your walls.

 

[tjhever]

The floors were damp when i lifted the carpet. I've just lifted the carpet off the wooden floor and all the boards are damp. In the area where there was a lot of springyness I found a plank that had been screwed to the floor (adjacent to the flow of the planks - it seems to keep them steady but not working) and when the carpet was down i thought this is was drop in the floor. I've taken up the plank and underneath that was dry and the floor was drier underneath the sofa and armchair (what on earth is going on!) I looked under the boards and the joists seemed to be fine but what i did notice was that there was a lot of rubble and rubbish under the floor and I couldn't see the airbricks despite only being a couple of foot away from them. I wonder if the dampness has been caused by blocked airbricks?

 

[Penners]

You describe the wooden floor as being damp to the touch. Are you sure it's damp? Just putting your hand on something is not always a reliable test - coldness and dampness can sometimes be mixed up. How do you know it's less damp under the furniture?

If you want to carry out a proper test on the wooden floor you could hire a Protimeter from a hire shop. Push the probes well into the wood to get a proper reading of its moisture content. Anything under 16% - 18% is probably fairly normal, and not much to worry about.

If you can't see any air bricks ventilating the void under the floor, you should certainly rectify this.