Floor thickness question

tileproowner

I visited a new house under construction to bid on the wood flooring (2,000 s/f of wood). The heat system is hydronic, the tubes are buried in 5" of concrete on grade (insulated underneath the tubes) the slab is recessed 2" from other areas of the house and the builder wants to put 2 layers of plywood down and then install the wood flooring on top nailed down. I am concerned that he is flying by the seat of his pants and asked if this was addressed with a heating engineer. I would rather see the floor brought up to height with a cement product and the wood (engineered) installed on that. Do you have any thoughts on the thickness( 2") of the wood build up on top of the concrete. I have never see that kind of thickness on top of the tubes, also is the distance of the tubes to the surface (6"+) if the floor is built up with gype-crete or similar and the wood installed floating or glued going to lead to any problems?   

STEVEusaPA

I think you're going to run into some problems

First, good luck missing the tubing when you install all that wood.  Second, a very poor transfer of heat. You're going to have to get a much hotter water temp to get the heat thru all that wood. 

If you have to get the tile floors flush with the wood floors, a better way to go would be to install wood sleepers, to get you to the subfloor height, then lightweight gypcrete flush to the sleepers, nailing the finish floor to the sleepers..  Keep in mind your still increasing the slab thickness, and now the pipes are buried deeper.

Also, you (someone) has to make sure the floors done this way have seperate temperature controls.

Finally, how would you ever make a repair on this floor, or find a leak, if done the first way proposed.