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Help & Advice Articles, Videos and How-to-Guides

Water repellents that cure penetrating damp problems

Categories: Damp Proofing

How can I identify penetrating damp?

Penetrating damp occurs when water penetrates the external material of a building; the moisture begins to seeps its way into the internal walls. Potentially the most damaging, penetrating damp contains salts and other pollutants which are then carried into the façade of the building. Sounds serious, right? And yes, it can be. Penetrating damp can cause a variety of different issues, including the corrosion of wall ties and metal framework, damage to timber, loss of strength and stability and the growth of algae and lichen on walls.

If penetrating damp is left untreated, the strength of the building’s facade can be affected, damp substrates can start to deteriorate in the freeze thaw cycles causing cracking and defacing of bricks. If your property is suffering with this it is vital you seek specialist help to stop the damage spreading.

Properties that are suffering from minor symptoms of penetrating damp can still experience changes that will affect your living. One prominent change is the building’s thermal conductivity; this will significantly reduce the property’s insulation, as the moisture continues to seep deeper into the interior walls.

It is not just your property that will suffer; any form of damp on internal surfaces can cause respiratory health problems, such as asthma.

What can I do to cure penetrating damp?

There are a variety of external water repellents you can use, depending on the severity of the damage.


Permagard’s Microshield is a water based repellent, suitable for external use on materials such as brick, concrete and other masonry. Simply apply one coat with this fast-acting repellent and it will produce a highly-protective barrier against rainwater. Applying the coating is easy; just use a brush, spray or roller, creating a clear and invisible layer within the masonry in minutes. Because of its mirco-porous nature, the product allows for rapid dry out, leaving the surfaces completely breathable.

We recommend that you do not apply the solution to green uncured cements/concretes, or DPC layers, yet it is perfectly safe to apply the repellent to alkaline cement surfaces, whether dry or damp.

Microshield Ultra

Our next product of choice is Microshield Ultra Masonry waterproofing cream. This is typically used to protect brickwork and façade against efflorescence and destruction as well as frost damage. This water based solution is a strong water repellent cream combined with a beading effect to mineral building materials. Made with silanes and siloxanes, Microshield Ultra works to protect and preserve materials, without visibly affecting its appearance. Once applied, water will simply bead and run off the material, preventing moisture seeping its way into the façade.

This highly-effective waterproofing cream will also improve your property’s thermal performance, saving you money on heating bills. The cream can be applied to a variety of building materials including brick, concrete, stone, limestone and render. Whilst being very versatile and suitable to many substances, we recommend using the product for concrete repair and remedial work.

Apply in a single coat and this fully breathable system will provide life-long protection due to its extra-ordinary penetration depth.

Water Repellent Solvent

Next, you can use a Solvent Water Repellent. This is a silicone resin designed to protect masonry against penetrating damp. You can apply the resin on a variety of materials, using a lamb wool roller, a brush or a coarse spray. For treating larger areas, a knapsack sprayer or piston pump is the easiest method to use. When using the spray, remember application should be applied slowly. When you apply the solvent, you should always start from the highest point, working from side to side, to allow the solvent to run. Two ‘wet on wet’ coats should be applied to the surface to maximise penetrations and surface protection.

For further advice please contact our technical help line for the right product for the job. Browse our range of Water Repellents.