Hi A few years ago we had hot water underfloor heating installed in our kitchen and diner. The builder laid 18mm ply on existing concrete floor and routed it by hand to take the pipes. Flooring contractor screeded over and laid Kardean tiles. A couple of tiles are now beginning to lift and when removed the plywood under was black and the layers delaminating. Black means the ply has got damp but we have had the pipework tested and there is no leak. Did our builder do wrong by using ply instead of preformed panels? Any thoughts guys?
Black ply is some serious amounts of moisture. 80s build shouldnt have rising damp. Either a old wall that’s not been protected from rising damp or you’ve got moisture coming in from somehwere. Bifold doors, cracked waste pipes beneath the screed? The ufh should be fine but you could have a leak beneath the screed somewhere.
