Koster 21 - 2 Component, Solvent-Free, Liquid Applied, Elastic & Crack Bridging Material - W 210 020

A multi purpose waterproofing product with excellent adhesion to dry and moist substrates. KOSTER 21 is a 2 component, solvent-free, liquid applied, elastic and crack bridging material. It is liquid applied and therefore seamless, which greatly eases application to complicated architectural details. Due to its UV stability it is suitable for indoor and outdoor use. The white color reflects sunlight and reduces building surface temperatures. The fast curing coating is highly flexible, resistant to occasional foot traffic, aging, hydrolysis, UV-rays, frost, and salt.

KOSTER 21 seals against synthetic oils and aliphatic hydrocarbons with high boiling points (up to 2 bar). KOSTER 21 is not resistant against substances with high aromatic hydrocarbon contents such as benzene, xylene, toluene, etc. In case of questions contact our technical support team. KOSTER 21 does not contain volatile organic compounds (VOC content = 0), is free of polyurethanes, isocyanates, and bitumen.

Unit Size

Coverage: Approx. 0.4 - 0.6 lb/sq ft

Fields of Application KOSTER 21 is a waterproofing material for positive side waterproofing of basements, concrete slabs, tanks, flat roofs, beneath tile, terraces or balconies, and similar applications. KOSTER 21 is also suitable as a protective coating against mineral oils and aliphatic hydrocarbons. KOSTER 21 is suitable for protection of surfaces in facilities with chemical and mechanical demands on the coatings, such as containment and skimming tanks.

Substrate The substrate must be free of standing water, loose particles or other bond inhibiting substances. Soiled substrates must be cleaned down to a solid layer. On interior corners, install a fillet of KOSTER Repair Mortar Plus approx. 24 hours before application of KOSTER 21. Exterior corners must be broken and rounded. 

KOSTER American Corporation is a subsidiary of KOSTER Bauchemie AG of Germany.

Founded in 1982 KÖSTER BAUCHEMIE AG specializes in the development and production of high-quality waterproofing products and systems. Today, KÖSTER forms a group of more than 20 companies with worldwide activities in more than 50 countries. Its headquarters are located in Aurich, Germany.

Our R&D facility, production and technical department are all located on the same campus in Virginia Beach, VA. This allows each department to work closely together to ensure each product conforms to the highest standards of quality. 

KOSTER operates two production facilities in Virginia Beach. The liquid facility produces all of our epoxy coatings while the powder facility produces our self-leveling underlayments as well as other cementitious waterproofing products. 

We place tremendous value on producing our products ourselves in order to ensure the highest level of quality control from development to application. We strongly believe in providing our customers with an excellent and safe experience with our products.