Koster NB 1 Grey Cementitious Waterproofing - 55 lb Bag - W 221 025

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Watertight (> 400 ft water head) cementitious waterproofing with subsequently crystallizing agents. Suitable for positive side and negative side waterproofing. A waterproofing made of KOSTER NB 1 Grey possesses excellent pressure and abrasion resistance.  For area waterproofing in new construction and restoration, e.g. waterproofing of basements and tanks.

KOSTER NB 1 Grey is Certified to NSF/ANSI 61

Unit Size 55 lb bag (W 221 025)

Coverage: One 55 lb bag will cover approx. 110 sq ft. A minimum of 0.5 lb/sq ft is required for most applications. If brush applied at 0.5 lb/sq ft, apply 2 coats at 0.25 lb/sq ft each.

• Compressive strength (28 days) > 30 N/mm2
• Flexural tensile strength (28 days) > 6 N/mm2
• Adhesive tensile strength > 1.5 N/mm2
• Waterproof against pressurized water (negative side) up to 13 bar


KOSTER NB 1 Grey is a rigid coating for waterproofing masonry and concrete. It forms a waterproof barrier on the substrate and it contains pore/capillary plugging and crystallizing agents. These penetrate into the substrate where they form crystals which fill voids and capillaries, producing an integral waterproofing effect. KOSTER NB 1 Grey is approved for use in drinking water environments according to NSF/ANSI 61. KOSTER NB 1 Grey is used on the positive or negative side of structures. It resists over 200 psi of hydrostatic pressure and is a permanent waterproofing system as long as the substrate remains sound. Freezing and thawing cycles will not affect the material. KOSTER NB 1 Grey is supplied in powder form. It can be mixed with water or a solution of KOSTER SB Bonding Emulsion and water. KOSTER SB Bonding Emulsion is added to improve curing and adhesion. KOSTER SB Bonding Emulsion also improves the abrasion resistance and elastic properties of the material.

Fields of Application KOSTER NB 1 Grey can be used in new construction and repair for horizontal and vertical waterproofing of concrete, masonry or cementitious plaster, on porous concrete, shotcrete, in wet rooms, bathrooms, showers, basements, elevator shafts, tunnels, leaking retaining walls, leaking ceilings, tanks, silos, sewage treatment plants, manholes, and drinking water tanks.

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.