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

Usually, the concrete slab is not 100% level and there are also utility lines on it. We recommend first applying a leveling screed, leveling insulation screed, or sand to level the surface before laying the insulation boards. If this is not possible, it is best to cut the insulation boards into smaller pieces so that they no longer float and rest well on the ground; afterwards, you can fill all the gaps with PU foam and then place a plastic layer on top.