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There are many different types of damp problems that can occur in your property, and each one has various possible solutions and treatments.

We have gathered some useful information on damp-proof injections, how they work, when to use them, and how much it costs.

What is Damp-Proof Injection?

A Damp-proof injection is a solution to some kinds of damp problems. It is a very common solution, and is known for being very effective! If applied correctly, it can last for several decades or longer. Put simply, damp-proof injections involve injecting a chemical treatment into the bottom of a wall. The treatment permeates through the brickwork to form a water-resistant barrier.

When To Use It?

Most walls have some kind of damp-proofing measures applied or built in when they are first built. This is often some kind of damp-proofing membrane. Damp-proof injections are usually used when the original damp proof membrane of the wall has failed. It is designed to be used on brick or stone walls – alternative damp proofing methods are available for walls made of different materials.

You should consider a damp-proof injection treatment if your wall has begun to show signs of rising damp. Signs of rising damp include tide marks or brown and yellow patches on the walls. These are caused by damp evaporation. If the marks are more than a metre up the wall then it could be a penetrating damp problem rather than rising damp. Salt deposits on the plastering can also be a sign of rising damp. The water rising up from the ground contains naturally occurring salt from the earth, and as the water evaporates the salt is left behind on the wall. Other signs of rising damp can include peeling wallpaper or paint, rotting skirting boards or flooring, a damp or musty smell and sometimes the presence of black mould.

If you aren’t sure whether you have rising damp or penetrating damp, or you don’t know whether damp-proofing injections are the right solution for you, then you might want to consider getting a survey. A damp-proofing specialist can survey the property, diagnose the specific damp problem, and recommend the most appropriate and effective solution.

What Can It Treat?

Damp-proof injections can effectively treat rising damp problems. It can also be applied to walls that have already suffered from water saturation. It is not always suitable for other types of damp problems, such as penetrating damp. This is because the holes are drilled into the bottom of the wall to stop the water coming up from the ground, but it does not stop water coming into the walls from other sources.

How Does It Work?

Now you have an idea of what damp-proof injections are, how do they work?

After the damp problem is diagnosed and damp-proofing injections have been deemed the most appropriate solution, small holes will be drilled along the bottom of the affected wall. The holes are then injected with the chemical treatment. It will usually have a cream or liquid consistency, and is a silicone based product. The active ingredient is silane.

The chemical treatment seeps into the brickwork and spreads horizontally and vertically. It is absorbed into the bricks without leaking out. Once it has diffused to cures, creating a water-repellent barrier which prevents water from the ground from rising up into the wall.

Some fittings and fixtures may need to be removed from the affected wall before the treatment can be applied. This could include skirting boards or fitted furniture. Some of the plaster along the bottom of the wall might also need to be removed, depending on the water damage. After the treatment has been applied, those sections of wall will need to be re-plastered.

If the treatment is applied incorrectly, it may not be very effective. If the holes are drilled too high the injection will prevent the damp from rising up the walls, but will not protect the floorboards, leading them to rot and ruin.

Benefits of Damp-Proof Injection?

Why are damp-proof injections so popular compared to other types of damp-proof treatment?

They are quick to install, and relatively non-intrusive. The liquid chemical treatments are even faster and simpler than the cream based products, as they cure quicker and are more concentrated so less injections are needed.

Damp-proof injections are a low hazard solution to damp, as they are non-flammable, non-caustic and solvent free.

How Much Does It Cost?

Now that you understand how damp-proof injections work, how much does it cost?

The cost of a damp-proof injection treatment depends on many things. If you have a large wall or a whole house to treat then this will be significantly more expensive than one small wall.

The condition of the wall before the treatment is applied could also affect the price, like the materials it is made from and the severity of the damage caused by the damp problem.

Prices will vary depending on your local area and the company you choose to use. For a standard domestic damp-proof injection treatment with a survey etc then you will be spending at least a few thousand pounds. This price will usually include a survey, internal plastering, and a guarantee. 

Can I Do It Myself?

Unless you are a trained damp-proof specialist, it is not recommended to apply damp-proof injections to the affected wall yourself. There is lots of room for error in the application of this chemical treatment, which could render the treatment ineffective or even compromise the stability of the walls themselves. You will also need specialist help to diagnose the cause of the damp, as rising damp is easily misdiagnosed and you may be applying the wrong treatment to your property.

If you want to bring down the cost of the treatment, you could speak to the company you use about prepping the area beforehand, such as removing fixtures, fittings and plaster. This would save them time and might bring down the labour cost of the job. You could also consider your own plastering after the treatment has been applied.

For more information about rising damp, how it can be treated with damp-proof injections, and what services we can offer to help you, please visit our rising damp page.