Wondered if anybody had any experience of insulating a concrete slab. I am looking at putting some insulation under a concrete slab which will have telehandler and tractor & muck spreader driving on it. Will polystyrene or standard Kingspan type insulation do it or will it have to be the more heavy duty stuff? i.e. 300/500/700kpa. Looking at 50mm of insulation under 200mm mesh reinforced slab. TIA