[RWebb]

I used some sort of thin membrane between the eng. wood flooring & the concrete. Ripped up the vinyl tile, left the black mastic coat on the concrete - concrete in parts, mastic in parts.

Just rolled the membrane out - taped it together & laid the flooring.

The membrane was esp. for that function - it has 2 layers of solid plastic with a 'crumple' or corrugated or bubble (or something - can you tell I didn't examine it closely?) in between. Flooring co. said it would cushion and quiet the eng. wood flooring.

Adjacent room has Marmoleum with a cork backing and it is nicer to walk on, so...