I'm in the process of converting an old barn into a heated shop and the old milk house into an office, we have the new rafters and false ceiling installed and the milk house is done except for the new ceiling and insulating, now for the tough questions, anybody use in floor heat in their shop where your putting in heavy equipment, I was thinking about 8 inches of cement in the floor but the cement guys are telling me 10-12 and not to put down the two inch insulation board under the cement period, they claim it'll crush due to the weight and cause the floor to crack over time and to just tie the heat tubes to rebar and lay it down first so its under the cement, the second problem is they are also telling me that in floor heat won't work good in cement that thick. I'm slightly confused on all this, first everyone recommends to insulate under the cement and thats what we did in the milk house but is it really needed if I only heat the shop to around 50-55 degrees, thats the temp of the ground anyhow inside a building thats heated so why would heat be lost into the ground if its already 50 some degrees and heat rises doesn't it? The next part of my question is why wouldn't the heat make it up through 10-12 inches of cement if heat rises? it makes it through 6 inches just fine, why not thicker? Would the cement and weight of what your running on the floor crush the 2 inch thick foam board under the cement? Is that thickness needed for heavy equipment? I plan on putting in a service pit to work on and service equipment and and want to make it all heavy enough to back loaded lowboys in and right now we weigh in at 110,000 lbs so I want to make it good enough to not worry about cracking the cement, my largest excavator weighs in at 60,000 and the cement people are worried about the vibration and weight in a short area. I don't want overkill but not to undersize it either. Someone out there has got to have experience with this and basically none of the cement guys have done anything with heavy equipment and don't know for sure, its kinda unique and not a big demand for like houses and driveways so I understand where they are coming from as far as experience goes. Tanks in advance for any input.