Concrete Waterproofing

The options for waterproofing a basement are external waterproofing, waterproof concrete, or cavity drain.

How we resolve failed concrete waterproofing projects

We work to repair 4–6 failed concrete waterproofing projects found within basements each month whereby the additive companies have left the contractor and engineer with a water ingress problem to sort out.

The major problem is that leaks occur behind finishes, so it is not possible to repair the problem without removing all of the internal finishes to establish the source of the leak.

We do provide waterproof concrete structures.

Additives fail due to poor workmanship, cracks, honeycombing, and most commonly defective joints, hydrophilic strips and water bars.

The MacLennan CrystalCoat system is a concrete waterproofing solution that gets applied directly after construction. MacLennan repairs all defects and waterproofs the concrete completely and effectively.

The system, when combined with our cavity drain, is guaranteed for 20 years.

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    - Failed Waterproofing Concrete.
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    - Horseshoe - Basement Vandex Waterproofing
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    Base Of Brick Wall New
    Waterproofing Membrane
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    - Failed Bentoite Basement Waterproofing
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Get in touch with our technical team today!

MacLennan Crystal Coat for Concrete Waterproofing

MacLennan CrystalCoat is a concrete waterproofing system that is applied to the surface of concrete to provide in-depth protection against the movement of moisture through the capillaries and hairline cracks within the concrete.

CrystalCoat consists of Portland cement, specially treated quartz and a compound of active chemicals, and is supplied in powdered form. It is either sprinkled onto fresh concrete or is mixed with water as a carrier and applied by means of brush or spray as a slurry for application to fully cured or older concrete or vertical surfaces.

The active chemicals in MacLennan CrystalCoat combine with the free lime and moisture present within the capillaries to form insoluble crystalline complexes which effectively block the capillaries and any minor shrinkage cracks to prevent any further movement of moisture to provide a totally dry surface to the concrete. Large areas can be quickly treated with MacLennan CrystalCoat.

The speed of application and the low material application rate (1kg/m2) makes MacLennan CrystalCoat a very low cost option for a large number of scenarios where concrete waterproofing is required. Because MacLennan CrystalCoat penetrates deep into the concrete, it does not leave a physical membrane to the surface of the concrete element and so is completely unaffected by loadings imposed by further elements of the build.

Key Benefits of CrystalCoat

  • It's easy to apply and can be sprinkled onto new concrete or applied as a simple slurry to vertical and cured concrete.
  • Permeates deep into the concrete to form a barrier against moisture that cannot be damaged or punctured.
  • Loading capabilities only limited by the strength of the concrete.
  • No physical membrane – subsequent concrete placement is ‘concrete to concrete’.
  • Can be applied by airless spray for quicker application.
  • Concrete treated with MacLennan's CrystalCoat remains vapour permeable, allowing the structure to ‘breath’.
  • Easy to detail and specify as the concrete surface becomes the membrane.

Please note that MacLennan CrystalCoat is not a decorative material. When applied as a slurry, the slurry residue remains on the surface of the concrete and can be unsightly. Where applied as a dry powder to green concrete and trowelled or power floated, uneven colouring or blotching may be apparent once the concrete is cured. If a decorative finish is required, other products should be considered. Please get in touch with MacLennan for further advice.

Concrete Properties

Concrete is a porous material with a micro structure of capillaries and fine cracks. The amount of reinforcement steel used within the concrete will control the size of the cracks by controlling the degree of shrinkage in the curing concrete. Formally BS8007 and BS8110, EN.

Crystal Coat Concrete Waterproofing

Why should I work with MacLennan?


We Design, supply and install. There's no split responsibility with MacLennan.


MacLennan live and breathe waterproofing, have a look at one of our free CPD seminars and find out!


MacLennan has the most comprehensive guarantees and insurances in the industry.

The Problem with Concrete Additives

The guarantees with these products are meaningless. They don’t cover design or consequential damages. Most of them only cover the value of the original material value. Once you exceed that value, you will have no guarantee whatsoever. If a leak occurs after fit-out, as it often does, then you have to pay for all repairs.

Waterproof concrete additives are the most expensive form of waterproofing because of the required construction to BS8007, requiring 30% additional reinforcement. The basements MacLennan design are built of ordinary concrete to BS8110. This saves thousands of pounds on steel and makes detailing of hydrophilic strips and external water barriers so much easier.

Read our technical guide on Concrete Additives

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Get in touch!

Ready to start a project or require more information about us?
Call us about your project or problem and we will be happy to help.

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0330 3200 240
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