Engineered oak flooring

[cartertim]

Hello,

I am about to lay an engineered wood flooring over part timber floor boards and part karndene covered concrete floor. both floors are in good condition and level, although there is a very slight difference in level between the wood and concrete floor.

i have been given conflicting advice/opinions regarding underlay. some have recommended no underlay and pinning the floor so that it isnt a floating floor while other a 6 mm fibreboard or 6mm ply.

i will be removing the skirtings and cutting in around door frams while ensuring i leave a gap for expansion but just not sure whether i need to lay a subfloor?

any advice will be greatly appreciated.

thanks

[welsh brickie]

if the floor is level,you must use a vapour barrier on the concrete with foam underlay.Dont nail it,its pointless as your floor is concrete and timber and will expand and contract on the different surfaces.
Also leave a 10mm gap around the perimiter.
When it comes to cutting around door casings you dont need a 10mm gap,leave 3 to 5mm and you can fill the gap with colour matched silicone.