I an extending a basement flat, which has a concrete slab, the carpet is just lain directly onto underlay onto the slab, no insulation under it, there was a damp proof course injected some time ago.. I'd like to incr the insulation of the flat (the new bit will have conc,insulation and screed)..but obviously at not great expense and not too much loss of head room.
i could just go for puker underlay, but would like to do more - though if putting say, 25mm celotex, would also need 18mm ply then floor covering..is there something out there that is stiff enough to do away with the ply on top? yet also really would help with insulation? or would it be more costly than celotex/ply? do advise, the ffl to ceiling at the mo is about 2500mm, so can afford to loss a little, but really not too much.. thank you.