KÖSTER 21 20kg

In stock
£166.00 Ex VAT
£199.20 Inc VAT
Koster 21 is a two component, solvent-free liquid applied, crack bridging elastic waterproofing product, which has exceptional adhesive qualities to dry and moist substrates.

Koster 21

This fast curing coating is highly flexible, the seamless membrane is resistant to the occasional foot traffic, UV rays, salt and frost.

Koster 21 seals against synthetic oils and aliphatic hydrocarbons with high boiling points. Not suitable for aromatic hydrocarbons such as benzene, xylene, toluene, etc.

Uses of Koster 21

Koster 21 is used on the positive side for waterproofing:

  • Basements
  • Concrete slabs
  • Tanks
  • Flat roofs
  • Terraces or balconies

Applying Koster 21

Koster 21 is applied in two coats, with the waiting time between coats dependent on local conditions of the waterproofed area. Vertical areas no foot traffic a minimum of 3 hours, 24 hours before light foot traffic on horizontal areas. Areas which are subject to cracking or at wall/floor junctions should have Koster Flex fabric embedded into the first layer whilst fresh. Roofs and balconies are completely reinforced, fresh coatings are water soluble and must be protected from rain until fully dry.

Waterproof & Dry - Trusted independent suppliers of Delta products 

If you have any technical questions about Koster 21 call our expert team on 0203 947 2972. Find out more about Koster waterproofing systems or browse our full range of Koster Tanking products.


  • Positive side waterproofing
  • Fast curing - Highly flexible - Seamless application
  • NO VOC’s - free of polyurethanes, isocyanates, and bitumen
  • Resistant to occasional foot traffic, aging, hydrolysis, UV-rays, frost, and salt
  • Reflects sunlight and reduces building surface temperatures
  • Suitable for new construction and repair on existing structures
More Information
Model DMS 244
SKU DEK21/20
Manufacturer Delta Membranes
Packaging Individual item
Size 20 kilo bucket
Dillution Mix Part A with Part B
Coverage 2.5 - 3kg m²
Colour White
CE Mark Yes
Country of Manufacture Germany

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