Structures that are built below the groundwater level (at the beaches of the water areas and at other sufficiently deep places) have to be measured for water insulation as so-called water pressure insulations.
Structures are usually made of concrete and must be insulated with elastomer bitumen membranes according to how deep below the water surface they are, noting how high the water surface may rise at the most. The lower surface of the building or structure must also be insulated and the insulation must be uniform under the floors of all the walls, for a sufficiently high height. The insulation must thus form what seems like a tight container around the structures. Performing the work requires lowering the groundwater surface sufficiently for construction work.
A sufficiently smooth bottom shingle is cast under the insulation of the lower surface. On top of it, it is possible to perform the lower surface's water insulation work (felt roofing, 2, 3 or even 4 times). A proper floor structure is cast on top of the water insulation. The water insulations must reach sufficiently far over the outer edges of the structure so that that they can be turned on the walls sufficiently after building the walls. The edges going over the insulation must be protected carefully for the entire process of wall and floor repairs, so that they do not get damaged. The insulation layers are overlaid on the walls for the insulation of the tasks, layer by layer. The lowest layers must be anchored to the wall structure reliably to stop runoffs. All the layers must be attached and sealed with particular care, because fixing the structures after the fact is very difficult.
Elastomer bitumen membranes of at least class TL2 are used as insulation, generally an Underlay Sheet K-MS 170/4000 (or-MS 170/3000)