Tätskikt

The waterproof layer behind the tiles

The tätskikt (waterproof membrane) is the watertight layer hidden behind the tiles in a bathroom. You never see it, but it is what actually keeps water away from the walls and floor structure. Tiles and grout let moisture through over time, so it is the membrane, not the surface, that does the protecting.

Where it is required

The building rules require floors and walls exposed to splashing or spilled water to have a waterproof membrane that stops moisture from reaching parts of the building, and rooms, that cannot handle damp. In bathrooms and shower rooms this normally applies to both walls and floors. In laundry rooms, toilet rooms and spaces with a water heater, a membrane on the floor is usually enough.

The protection is not only on the surfaces. It also covers seams, the seals around pipes and fixings, and the connection to the floor drain (golvbrunn). It is often right there, at the drain and the pipe penetrations, that faults appear.

What you do as a buyer

A failed membrane rarely shows on the outside, but the damp underneath can lead to mould and an expensive rebuild of the whole wet room. So ask how old the wet room is and whether there is a quality document (kvalitetsdokument) from when the bathroom was built or renovated. If the bathroom is older or the paperwork is missing, ask the inspector (besiktningsman) to look especially closely at the floor drain, the seams and any signs of damp, so you know what you are taking on before the bidding starts.