Hi folks, So, we're renovating (rebuilding, really) a really lousily built 1970s tract ranch home in the PNW. The floor is 4' O.C. beams supporting 1.5" car decking over which we laid 1/2" CDX ply. It's only 904 sq ft, so hardly massive. The original intention was that we'd be laying 3/4" ply in strips and putting the PEX for the radiant floor between them, then overlaying that with T+G engineered wood flooring - but we recently decided that we'd like to use trutop microcement as our flooring in the living / kitchen / dining area (roughly half the house). Having spoken to TruTop's technical advisor a while back they didn't see any problems with this being laid over the plywood and PEX but... We're trying to get into the house a bit quicker, and cutting that much ply (and laying it) is going to take me a while. I'm trying to work out whether the following structure would be a terrible plan: TOP--- TruTop Microcement +/- Self-levelling compound +/- Crack isolation membrane Sand Mix Cement in between the pex pipe - levelled off at roughly the top of the pipe (our heating supplier spec'd 3/4" pipe laid ~10" O.C.). [Existing ply, Car decking, Beams] Any thoughts from people who've worked with this 4'o.c. flooring would be particularly welcome We don't really have any more space to make the floor thicker, sadly. So we're really limited to about an 1 1/4", maybe just over, from the existing ply to the top surface of the floor. We've already taken the exterior doors as high as we can get away with, without replacing the headers...which would require more reframing than we've already done!