Floating Chipboard Floor over unlevel stone flags

[antmcc]

I'm replacing my Kitchen and in doing so I discovered that the old screed on the floor had separated from the base, I've hacked this off and found the original sandstone flags (laid on earth).

The flags are very unlevel, up to 40mm and hence it would swallow lots of self levelling compound (cost...!), but the thinnest sections of the old floor were only 4 mm on top of the flags, so I can't use screed. I thought of installing a chipboard floating floor over a DPM, but I don't have much height to play with.

Therefore I'm after some thoughts..

If I laid sand onto the flags (to level them up) then DPM, then some thin insulation (6mm depron?) could I float a chipboard floor on this? I'm not convinced whether this would be better or worse than a really thin screed, because the old screed lifted (I assume because of damp through the original stone base), so I expect any new screed would do the same.


Thanks

Ant

 

[JerryM]

i don't like wood on solid floors (only with void/ventilation underneath) due to durability.

i would fill the big holes with mortar (5:1 grit sand:cement) followed by a self leveller/liquid dpm.

i don't think there is a way of getting a plastic dpm sheet to work with the depth.

 

[antmcc]

Jerry,

Thanks, what durability issues could I expect from laying sheet DPM, thin insulation and chipboard? I'm just concerned if I use thin screed it will lift the same as the old surface did and destroy all my hard work

Thanks for your advice

Ant

 

[JerryM]

i like to trap the damp at the surface that it's coming off. i also find chipboard (even the flooring grade) susceptible to any dampness.

whilst i'm sure the dpm sheet and chipboard will work, i'm just suggesting giving a thought to alternatives that are more akin to the environment you've got - ie a liquid dpm (something like an epoxy resin damp proof membrane, neoprene primer followed by self leveller).

i suppose it all depends on how much damp is coming off the flags. suggest tape a piece of plastic for 24hrs and see how much moisture appears. if the damp is high then it will just sit under the dpm sheet and i feel eventually gives rise to smells or dampness above it unless it is well sealed around the perimeter.

in terms of coming up/lifting then i would try a small area 1st of whatever method. have a visit to your local builders merchants and see what they would offer along with a look on this site a similar problems. then make your mind up.

 

[antmcc]

Thanks, I'll try the plastic trick and see how much of a problem I've really got