Oak floor over old limecrete slab

[AliAli44]

Hello
I've just moved into an edwardian house, end terrace, with a limecrete slab in the sitting room. I would like to install a solid oak floor here, and have just taken up the carpet, under which was underlay, and under that, a damp proof membrane. The underside of the membrane was damp in patches (but not all over), and there were small puddles of moisture in a few places. The slab itself had what I'd assume to be a screed laid over it, this has broken up in three main areas, relatively small patches, given the size of the room. I'd assume this is because moisture being breathed out by the limecrete caused it to delaminate. Skirting boards look OK, as do the walls, bar a very small bit by the front door. Am I OK, do you think, to put a solid oak floor over this? A friend recommended laying the floor on a double layer of 1200 guage DPM, followed by 2by 1 or 2 by 2 floating batons, with celotex insulation between those. I'm a bit confused as to why the DPM that was already there had not caused issues elsewhere in the room, given that limecrete is breathable?

 

[Cubist]

I would not use solid oak. Theres too much risk with a concrete slab below for the timbers to warp and buckle owing to moisture accumulation either from the slab, the walls or simply from the atmosphere. Wiser to go with an engineered plank with say a 6mm oak veneer. Pretty much the same price and appearance and much less guilt if it ever fails.

Your mates recommendation suggests intent to nail or screw down the floorboards to the batons. That really is not necessary with modern close fit tongue and groove oak boards. You can construct such floors to effectively float immediately above the damp membrane.