How do I place my insulation boards directly on the concrete slab?

Usually the concrete slab is not 100% flat and there are also utility pipes on top. We recommend that you first place a filling screed, insulating screed or sand to level out the surface before laying the insulation boards. If this does not work, it is best to cut the insulation boards into smaller pieces so that they no longer float and support well on the ground, after which you can spray all the cracks with PU foam and then place a plastic layer above it.