Swimming pools can present a special challenge for waterproofing, in that water pressure can affect the outside and 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 KOSTER recommends to waterproof swimming pools with a combination of positive and negative side waterproofing.
The substrate must be clean and sound. Damaged areas, cracks, and holes are to be repaired with KOSTER Repair Mortar beforehand. Weak or salt contaminated substrates are to be treated with KOSTER Polysil TG 500. Rounded fillets are installed using KOSTER Repair Mortar in inside corners. Edges are rounded off.
A negative side waterproofing is applied with two layers of the cementitious slurry KOSTER 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 KOSTER NB Elastic Grey are applied. KOSTER NB Elastic Grey is a light colored, waterproof, elastic, crack-bridging coating with excellent adhesion to mineral substrates. The material protects against movements up to 2 mm within the construction. KOSTER NB Elastic Grey can also be used with a flexible tile adhesive such as KOSTER BD Flexible Tile Adhesive, and subsequently directly tiled over.
Pipe and cable penetrations, drains, and other outflows can be safely and permanently sealed against water ingress with the flexible plastic sealing compound KOSTER KB Flex 200.
Always adhere to the specifications in the respective Technical Guidelines.