Swimming pools can present a special challenge for waterproofing in that water pressure can affect the outside as well as the inside of the construction. When swimming pools are built directly in the ground, water pressure builds from the inside to the outside just like in a regular water tank. However, if there is no water in the pool due to maintenance or time of year, water pressure from ground moisture surrounding the pool will build from the outside to the inside as similar with a basement. That is why KÖSTER recommends to waterproof swimming pools with a combination of positive and negative side waterproofing.
The substrate has to be clean and sound. Damaged areas as well as cracks and holes are to be repaired with KÖSTER WP Mortar beforehand. Weak or salt contaminated substrates are to be treated with KÖSTER Polysil TG 500. Rounded fillets are installed using KÖSTER WP Mortar in 90-Degree inside corners. Edges are rounded off.
A negative side waterproofing is applied with two layers of the cementitious slurry KÖSTER NB 1 Grey. The material penetrates into the mineral substrate and becomes an integral part of the construction, protecting against negative and positive water pressure. Afterwards, two-layers of KÖSTER NB Elastic Grey are applied. KÖSTER NB Elastic Grey is a light colored, waterproof, elastic, crack-bridging coating with excellent adhesion to all mineral substrates. The material protects against movements up to 2 mm within the construction. KÖSTER NB Elastic grey can also be used with a flexible tile adhesive such as KÖSTER BD Flexible Tile Adhesive and subsequently directly tiled over.
Pipe and cable penetrations, such as drains and other outflows, can be safely and permanently sealed against water ingress with the flexible plastic sealing compound KÖSTER KB-Flex 200.
Always adhere to the specifications in the respective Technical Guidelines.