Laying Plywood onto concrete

[arh]

Hi
Had a solid wood floor installer advise me to lay 12mm WBP plywood over my concrete floor to block moisture and help to even floor.

Is this the best thickness to use?
Should I lay a DPM under the ply?
He recommended screwing and glueing this - what type of screws and glue should be used?
Some of the floor is floorboards I guess I will only need to screw into this?

Thanks.

 

[WFRN]

Is the concrete new or existing?

Ply will not stop moisture, a DPM is required. National wood Flooring association suggest a polythene membrane as a DPM and then install the ply over this (this is where you have a problem) fixing through the polythene makes holes and defeats the object, so you could lay it floating but if the floor is not reasonably level the floor will be bouncy. 12mm ply is not sufficient to nail into unless using staples or short nails i would get 22 mm. The other option is to use kiln dried battens 22mm and glue and screw these direct to the concrete at 40cm centres, put insulation between the battens and use a sisalkraft moistop (bitumen backed building paper) over the battens as a moisture barrier and then nail the floor into the battens through the paper. Both systems are used and proved.