Hey. I have a question nobody seems to be able to answer: We're building an 1100 sqft ranch on a monolithic slab w/ 2" hard foam insulation under slab (+ crushed stone & eps vapor barrier), and 2" hard foam insulation vertically around sides/edges of slab and subfloor above. On top of the slab will be a wood subfloor web-truss system where the electric & plumbing & hydronic floor heating panels w/ PEX tubing will be located - as these will not be buried in the concrete (subfloor space height around 18" from top of slab up to bottom of flooring). Here's my Question: Do we also need another 2" hard foam board on top of the slab? Or is the 2" foam board under the slab + the 2" foam board vertically around sides/edges of slab and subfloor enough to counter heat loss from above in conjunction w/ any heat from the PEX hydronic heating tubes located directly under the floor above? Please let me know your opinion as I'm not sure if a second 2" foam board insulation on top of the slab is really necessary or not. Thank u VERY much in advance. Look forward 2 hearing your answer!