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PermaSEAL Flexible Tanking Slurry

100% of 100
£76.00 Ex VAT
£91.20 Inc VAT

A waterproof and highly flexible coating system for brickwork, masonry and concrete.

Flexible Tanking System - Grey

PermaSEAL Flexible Tanking Slurry is a waterproof and highly flexible coating system for brickwork, masonry and concrete.

This flexible waterproof slurry combines a blend of Portland cements, quality graded aggregates and a high strength liquid polymer. These ingredients combine to provide a waterproofing solution you can trust above and below ground. It provides excellent adhesion to construction surfaces and is safe to apply on damp substrates. Its flexibility means it is suitable for areas at risk of movement in both external and internal environments.

When it comes to the application, ease of use is guaranteed. The components are designed to be mixed together easily on site and applied directly to the surface by brush.

Uses of PermaSEAL Flexible Tanking Slurry

PermaSEAL’s flexible tanking system is suitable for waterproofing concrete, brickwork or stone in the following situations:

  • Tanking of basements, cellars, lift pits
  • Above ground damp proofing
  • Podium decks, balconies/terraces, flat roofs
  • Sealing of tanks and ducts
  • Internal and external waterproofing
  • Lining of storage tanks for potable water
  • Coating of brick and block work structures
  • Waterproofing to BS 8102:2022 for Type A shallow basement structures – Grades 1, 2 and 3

Note: It can be used in areas that are subject to vibration or minor movements. 

Applying Flexible Tanking Slurry

PermaSEAL Flexible Tanking Slurry is easy to apply. For full instructions consult the technical guidance documents in the download tab.


All contact surfaces must be clean, sound and well-keyed. All loose materials and previous coatings need to be removed.

Note: Any areas with voids can be filled with PermaSEAL Fillet Seal prior to tanking. Any physical water ingress should be stopped with PermaSEAL Water Stop before over coating with PermaSEAL Flexible Tanking.


Dilute Permagard SBR Bonding Additive 1:1 (by volume) with clean water. Then apply to the surface with a roller, brush or spray. Allow 30 minutes for the primer to become tacky to the touch.


Remove contents from the bucket. Shake the liquid component and allow to settle. Pour the liquid into an empty bucket. Using an electric paddle, slowly start to add the powder into the bucket. Do this slowly to reduce dust generation. Next, add all of the powder and increase speed so vigorous mixing is achieved. Mix for two minutes and ensure that all powder is incorporated.

Mix for a further 1 minute to ensure the product is free of any lumps. Tap water can now be added to achieve the desired consistency. A maximum of 0.5 litres of tap water can be added without it affecting the crack bridging properties. The liquid/powder ratio is 1:3. If smaller batches are required it is imperative that this ratio is maintained.

Important note: Do not add any additional components e.g. sand, cement etc, as this will dramatically impact the properties of the product.

Applying the flexible tanking slurry

PermaSEAL Flexible Tanking should be applied by brush, trowel or roller in a minimum of two coats. The first coat should be brushed in a horizontal direction down to the floor and across the fillet if applicable to a minimum thickness of 1mm.

The second coat should be applied once the first coat has had sufficient time to cure to a state that it will accept the second coat without being damaged. 

Apply a second coat of PermaSEAL Flexible Tanking in a vertical direction again covering the fillet if applicable.

Note: Do not leave more than 24 hours between coats.

Curing and Ventilation

PermaSEAL Flexible Tanking is a cement-based coating so will dry with the same characteristics as concrete. It is essential that the coating does not dry too fast as cracking could occur.

Note: When used externally in warm or windy weather, the slurry must be protected to prevent drying too quickly as cracking may occur.

Finish and Decoration

PermaSEAL Flexible Tanking should always be covered by a minimum 10mm coat of 4:1 sand and cement render, a 1:1:6 Lime based render or PermaSEAL Renovating Plaster.

After this render coat has been applied dot and dab plaster board or a multi finish can be applied. Any initial decoration should be considered as temporary and restricted to a low cost trade emulsion. Plastic, vinyl or eggshell paints should not be used.

Permaseal - Complete Solutions. Made Possible.

Our flexible tanking slurry is part of the PermaSEAL range and represents quality, value and technical excellence. If you have any questions about tanking basements or above ground waterproofing please contact our expert team.  


  • Two component product supplied in a bucket for convenience
  • Crack-bridging capabilities
  • Highly flexible waterproofing slurry
  • Resists both positive and negative water pressure 
  • Suitable for both internal and external use
  • Excellent adhesion to prepared surfaces
  • Easy to apply by brush
  • Conforms to BS 8102:2022 as a polymer-cement based waterproof coating for Type A shallow basement structures – Grades 1, 2 and 3

Flexible Slurry for Flood Resilience

PermaSEAL Flexible Tanking Slurry is part of our flood protection range. It can be used as an alternative to a standard slurry, imparting extra flexibility. It can be used internally up to 600mm to slow the ingress of flood water.



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