concrete floor very cold and damp - what to do?

[mrmisior]

Hi
Looking for ideas and any input is welcome.
I have a concrete slab in the ground floor. On top of it is a very thin layer of a leveling compound which is cracked here and there revealing the solid concrete. Carpeted over.
I took reading from underneath the carpet and the temperature of the slab is similar to the outside - today 10C outside, slab 13C.
This results in a very cold house.
Also, I get damp in the house up to 80% RH, however no sign of damp on the walls and no leaks.
Is it possible that the damp comes from the concrete?
What are the solutions to insulate the slab to stop the cold and damp?
Is it wise to install timber subfloor on top of the slab and insulate with celotex between the studs?
The timber would surely rot if not damp proofed somehow?
Please help.
Michael

 

[John D v2.0]

I doubt the humidity Comess from the slab, but it may be damp.
Put a plastic sheet or something on it and leave over night, see if there is condensation forming on it.
You should insulate if there's space to improve comfort, but you should make sure there's adequate ventilation and not excessive moisture generated on the house. Also heated properly.

For the insulation you can lay a DPM then a timber frame with full fill insulation eg celotex or glass wool depending on budget and head height. The hard part will be sorting out the doors and skirtings.

 

[endecotp]

What are the solutions to insulate the slab to stop the cold and damp?
Is it wise to install timber subfloor on top of the slab and insulate with celotex between the studs?

You don't need timber, except at the edges of the room. (Except perhaps in kitchen & bathroom where the heavy loads require more support.). Lay insulation boards in a continous layer, and then floating tongue-and-groove flooring e.g. chipboard / OSB / ply over that.

Celotex & Kingspan have documents describing this.

Electrics, plumbing, doors & windows etc. are all potential problems.

 

[mrmisior]

Thank you for the answers.
No problems with electrics, plumbing as these are over 5 inches of the floor.
Internal doors will be fine: there is just plasterboard above them so I can rise.
External door is a challenge. I think that I could leave 4ft square of the floor, by the door unchanged and this way will have a 4 inches step up. Is this OK?

Is it best to remove existing skirting or rather fit the new timber frame to it?

 

[endecotp]

No problems with electrics, plumbing as these are over 5 inches of the floor.

You don't want the sockets or radiators to be too low.

External door is a challenge. I think that I could leave 4ft square of the floor, by the door unchanged and this way will have a 4 inches step up. Is this OK?

It could look very peculiar IMO.

Is it best to remove existing skirting or rather fit the new timber frame to it?

Whatever's most convenient I guess. The new battens need to be supported from the concrete, but attaching them to the old skirting might be helpful during construction. Otherwise, you might be able to re-use the skrting if you remove it carefully.