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PermaSEAL Crystalline Cementitious Tanking Grey 20kg Bucket

£33.50 Ex VAT
£40.20 Inc VAT

Long lasting cement-based crystalline tanking slurry for waterproofing masonry and concrete.

Crystalline Waterproofing Slurry

PermaSEAL Crystalline Cementitious Tanking is a crystalline tanking slurry that provides a waterproof coating for concrete and masonry above and below ground.

As a cementitious (cement-based) tanking slurry, PermaSEAL Crystalline Cementitious Tanking combines quality graded aggregates and chemical modifiers with a blend of Portland cements. These elements combine to form insoluble crystals within any capillaries in the substrate, effectively blocking the passage of water.

It’s an easy to use product that is mixed on site and applied simply with a brush or specialist spray. The crystalline tanking compound is designed to adhere to various surfaces and can also be applied to damp substrates.

You can find our standard cementitious tanking slurry in grey and white if required.

Uses of PermaSEAL Crystalline Cementitious Tanking

This crystalline tanking slurry can be used in the following applications:

  • Basement & cellar tanking
  • Coating brick & blockwork structures such as garages (surfaces must be flat before application)
  • Sealing tanks and ducts
  • Lining of storage tanks for potable water
  • Drinking water structures

How to apply crystalline tanking


Preparing the surface: Start by making sure that all surfaces are free from any previous coatings as well as all loose material and dust. The substrate should be clean and sound. Carry out any repairs to existing cracks, holes or flatten undulating surfaces or concrete blocks with PermaSEAL Fillet Seal.

You will also need to create a fillet joint at the wall floor junction – you can read how to do this in our guide to cellar tanking.

Important Note: Priming is NOT NECESSARY. On dry surfaces, you should wet out the surface.

Mixing the crystalline slurry: PermaSEAL Crystalline Cementitious Tanking is mixed on site with water. The slurry comes in 20kg units. You will need 6-7 litres of clean water per 20 kg of dry material to create the correct tanking coating.

Pour the required amount of water into a suitable bucket or other mixing vessel. Now slowly add the powder whilst continuously mixing with a slow speed high torque drill with a mortar mixing paddle. Mix for three minutes once all the powder has been added – you are looking to achieve a creamy consistency.

Applying Crystalline Tanking

PermaSEAL Crystalline Cementitious Tanking is easy to apply with a brush or spray. You need to apply two coats of between 1.5mm and 2mm thickness per coat.

The first coat should be applied in a horizontal direction all the way down to the fillet level. The second coat of crystalline tanking slurry should be applied in a vertical direction. Make sure you cover the fillet with the coating. 

If leaks occur, drill 12 mm holes adjacent to the leak and seal with PermaSEAL Water Stop. Do not retemper stiffened material.

IMPORTANT NOTE: Do not apply PermaSEAL Crystalline Cementitious Tanking to frost-filled surfaces or when the temperature is 5°C or below.

Crystalline Tanking slurry coverage

A 20 kg pack is sufficient to cover the following:

Coarse surface: 2.5kg to 3kg/m²/coat 6.5 to 8m² per 20 kg unit/ coat.

Smooth surface: 2kg to 2.5kg/m²/coat 8 to 10m² per 20 kg unit/ coat.

Please note 2 coats are always required.


Permagard – Providing Tanking Solutions

If you are looking for a cementitious tanking solution or need more general advice on basement waterproofing then contact our expert team. 


  • Single component crustalline Tanking (just add water)
  • Easy to use product
  • High performance & long lasting tanking solution
  • Safe to apply on damp substrates
  • Suitable for above or below ground applications
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