Can a basement be waterproofed retrospectively?

A basement can be waterproofed after construction with ALLESDICHT liquid-applied waterproofing. Waterproofing can be carried out externally or internally; the appropriate approach depends on the level of water exposure and access to the basement wall. External waterproofing is the more reliable option because it intercepts water on the water-facing side of the wall. The wall is excavated, the substrate is cleaned and prepared to provide a sound surface, and ALLESDICHT is applied in several coats. Once dry, it forms a seamless, crack-bridging rubber membrane that adheres to concrete, masonry and bitumen and bridges fine settlement cracks.

At the junction between the wall and the base slab and around penetrations, mesh reinforcement is incorporated into the waterproofing. The required dry-film thickness depends on the level of water exposure: around 3 mm is sufficient for ground moisture, while approximately 4 mm is required where water accumulates or is under pressure.

Where the external side is inaccessible, for example because of adjoining structures or walkways, internal waterproofing can be considered. Applied on the side away from the water, it is particularly suitable for ground moisture and non-pressurised water where the substrate and level of exposure permit. The requirements for internal waterproofing are substantially higher where water is under pressure, so the waterproofing design must be assessed for the relevant water load before work begins.

Whichever method is used, the design must account for the relevant water load, and thorough substrate preparation is essential. Loose plaster, efflorescence and contamination must be completely removed before application. The waterproofed surface can then be plastered or clad.