Damp Proofing Injection for Building Walls in London


The most common moisture problem effecting homes throughout London is a phenomenon called rising damp in the walls. Rising damp refers to the movement of water from the earth up through the walls of a building via capillary action.


  • Capillary Action: the ability of a liquid to flow counter to the force of gravity in a narrow space due to the intermolecular forces such as surface tension and adhesion between the liquid and the solid surface surrounding it.
    • In real English: this is what happens when you dip a paintbrush into water and the water “wicks” up the fibers of the brush.


Capillary Action Draws Water up Against Gravity


There are tiny spaces in brick, concrete and other porous construction materials which wick water up the walls from the ground and into your home. Eventually the moisture will evaporate, but in the humid maritime climate of London the rising damp can reach a full meter above the ground before all the water evaporates.


Capillary Action Draws Water up Against Gravity


Rising damp is often made worse by the presence of below grade membranes along the foundation which prevent ground moisture from leaving through the exterior wall surfaces. This causes the moisture to reach even higher before finally evaporating, only after damaging or staining walls.


Damp Proof Course

Damp proof course (DPC) is a physical barrier installed 10-15 cm above the natural ground level during construction to stop moisture from passing to the wall above. The course is made of an impervious material such as hot bitumen, mastic concrete or metal sheeting which interrupt the capillary action and block the flow of water up the wall.


Capillary Action Draws Water up Against Gravity


Damp proof course is typically very effective. However, these materials eventually fail due to natural deterioration over many years, or they may give out prematurely due to poor installation.

Reinstalling damp proofing is, as you may expect, both disruptive and expensive. If the building in question is one of the older or historical buildings in London, with rubble or cavity walls, it can be nearly impossible to achieve the solid horizontal barrier necessary for successful damp proof coursing.

Chemical Damp Proofing Injection

Instead of reinstalling a mechanical damp proof course, you may consider damp proofing injection. This is a chemical technique which involves injecting a water repellant fluid into the masonry. The fluid travels through the same capillaries that wick water from the ground up into the walls of your home, leaving a water-repellent barrier along them that stops moisture from moving upwards.  

How Damp Proofing Injection is Done

To inject a chemical DPC into a building, holes are drilled in the wall 15 cm above the external ground level. These holes are spaced 1 meter apart all along the length of the effected wall. In a cavity wall, it is necessary to drill in both internal and external walls. The damp proofing liquid is then injected into the holes and spreads laterally through the capillaries of the wall to form an impermeable, continuous barrier.

Capillary Action Draws Water up Against Gravity

What are the Chemicals used for Damp Proofing Injection?

The original chemical damp proof courses were silicone based. These fluids were inefficient and messy, and often failed to fully seal the wall. This has given chemical damp proofing a poor reputation.

Fortunately modern chemical damp proof courses are much better. They come in liquids, gels and creams which are water based and emulsify inside the wall. They make injection easy and precise. Additionally these chemicals are safe to handle. There are many different formulas available. The one for your home depends on your specific problem and the current state of your masonry. It is best to seek the counsel of a damp proof specialist in London to pick the best option for your situation.

A Few Damp Proofing Injection Fluids


  • Triton Injection Mortar: A single ingredient product made of quartz, this mortar is odorless and easy to work with. It forms a crystalline layer along the capillaries of the wall stopping the migration of moisture. 
  • Dryzone Damp Proofing Cream: Quick and easy to install, Dryzone’s cream is safe to handle. It forms a water-resistant resin within the masonry capillaries that effectively stops rising damp. Rapidly becoming one of the most popular chemical DPC options available.
  • Thixotropic Gel: The very latest DPC option is a water soluble gel that goes through a chemical reaction within your walls to fill the capillary networks with silicone resin. The cool part- the coating is permeable to water vapor, allowing the wall to breathe and dry out quickly, thus minimizing damage.


DIY Damp Proofing Injection?

There are many DIY damp proof injection kits available, but the process is not always straightforward. Each building has its own unique issues to be resolved. To ensure your home is properly damp proofed and thus to avoid future expense and headache, it is best to leave chemical damp proof course injection to the professionals.


Capillary Action Draws Water up Against Gravity


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