Seal floor slab

Technologien und Beratung für den Betonbau - B.T. innovation

Professional sealing of floor slabs according to DIN

Moisture is the weathering agent that causes the most lasting damage to the building fabric. Seamless sealing is therefore important in all areas of the building. In particular, the floor slab is exposed to moisture from the ground, so its sealing against soil moisture is of great importance. The requirements for sealing a floor slab and its professional execution are regulated in DIN 18195 (2017) “Sealing of structures”.

The floor slab can be confronted with moisture in different ways. These load cases each require different sealing measures, which are regulated in DIN. A distinction is made between:

  • Capillary rising soil moisture according to DIN 18195-4 is always taken into account during the execution and sealing of floor slabs
  • Non-pressing water according to DIN 18195-5 arises from service water, precipitation water or seepage water
  • Sealing against water under pressure (also groundwater) according to DIN 18195-6
  • Sealing against rising seepage water according to DIN 18195-6
  • Condensation water precipitates indoors when moisture condenses
  • Residual moisture from the substrate escapes from screeds, for example, and must not penetrate into the floor covering.

With regard to sealing the floor slab to the ground, the first four types of moisture are relevant. In order to shield these reliably, DIN stipulates that the areas in contact with the ground must be completely sealed off. The FlächenElast® product range from BT Innovation is ideally suited for this area of application.

  • Surface sealing
  • Sealing of construction and connection joints
  • Sealings and penetrations
Various methods are used to seal floor slabs over a wide area; application by bonding, rolling, filling, painting or spraying is possible. The waterproofing layer is reinforced by inserting foil, fabric or fleece. The sealants from B.T. Innovation’s FlächenElast® range can be applied by roller. The modified polymer product can be applied to both vertical and horizontal surfaces and, thanks to its bitumen compatibility, bonds easily and permanently to the masonry barrier. The product can be used wherever there is a risk of pressurized water; the membrane covers crack widths of up to 5 mm without any problems. Not absolutely necessary for surface waterproofing, fabric or fleece inserts are indispensable at the movement and edge joints. This measure prevents the formation of cracks, via the execution of loops can avoid stresses and movements between pavement fields. These measures are also required where partition rails are incorporated at passages. Flanges or collars are used where penetrations require special measures for sealing the floor slab. The surface sealing is connected to the flanges via fabric or fleece.

Reliable sealing, which protects the floor slab in contact with the ground from soil moisture and other types of moisture, is thoroughly planned in advance. The required sealing measures with their connections should be shown in detail in the execution planning. This also applies to the connection to the thermal insulation or to the basement wall. The conditions on site, the planned floor covering and the intended use must be taken into account. In particular, the design water level at the building site, the basement construction (if available) as well as its layout and size are taken into account in the choice of sealing.

In existing buildings, it sometimes happens that a floor slab has to be subsequently sealed. Surface sealing for brushing on has also proven itself there. For subsequent interior waterproofing, the most important requirement is a load-bearing and clean substrate; any substances that may have a separating effect must be removed in advance. Depending on the surface and condition of the floor slab, priming is recommended. When sealing the floor slab at a later date, it should also be noted that a sealing measure can often only be effective once the cause of the moisture has been eliminated.

In the new DIN version 18195, sealing against rising damp in building components in contact with the ground is generally prescribed as a minimum standard. However, environmental conditions can change due to various factors, the best example being the many flood disasters in recent years. The ideal solution is therefore a sealing that is prepared for everything and reliably ensures a tight structure not only in the event of rising damp, but also in more extreme load cases such as water under pressure.

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