What is Tanking Slurry?

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Even though damp is a risk for many properties, it can sometimes be overlooked. When damp does take hold, it can cause a lot of damage and problems through your home. Excess moisture doesn’t look great on walls or floors. Plus, it can potentially cause health concerns.

Along with this, damp can cause structural issues. This means that homeowners should deal with damp at the earliest point. Fortunately, most types of damp can be fixed relatively easily.

Tanking slurry is a popular product, it can help you to deal with penetrating damp in many different situations. So, what is tanking slurry?

Tanking slurry is highly effective at preventing damp and water leakage. This means that you can use it to stop seepage, leakage and damp from penetrating walls and floors. It comes in powder form and needs mixing with water.

The powder is made from a blend of cements, chemicals and aggregates that work to prevent water getting through walls and floors.

It usually requires a minimum of two coats, and this will create a waterproof barrier. This will keep properties protected from damp and help to maintain structural integrity.

How Does Tanking Slurry Work?

Tanking slurry works by stopping moisture from penetrating walls and floors. You need to apply this solution in a minimum of two coats.

The powder will need mixing before application. Once mixed it should have a thick creamy consistency. At this point, it forms insoluble crystals, that help to stop water from passing through capillaries in walls and floors.

The solution is applied directly using a brush. The blend of chemicals and aggregates will help to enhance abrasion resistance, bond and strength. Some types of tanking slurry will also contain an acrylic polymer that makes it even more effective than cement.

For tanking slurry to work, it’s important to prepare surfaces correctly. You will need to remove things like render, plaster, and paint, as well as any other coatings. If the surface is brand new, then tanking slurry can be applied directly to the walls and floors. To ensure that it bonds to the surface, it also helps to dampen them slightly prior to application.

What Jobs Can Tanking Slurry Be Used For?

The main job of tanking slurry is to stop damp and moisture from penetrating walls and floors. As a result, you can use it in a range of jobs. While damp can form in a range of areas, it is commonly seen in rooms underground such as cellars and basements.

As basements are located below ground, they’re highly likely to suffer from damp. This is because they are surrounded by moist ground outside. So, as the ground becomes saturated, it can penetrate the walls and floors. When tanking slurry is used, it can help to form a strong barrier that prevents water ingress.

Tanking slurry can also be used on outbuildings of properties, such as brick sheds and garages. These will often have a single skin and might suffer from damp. This makes it a highly effective solution.

Single skin refers to the use of one layer of brick. Exposure to the elements can cause water to get through the wall.

When is Tanking Slurry Not a Good Idea?

While tanking slurry is extremely effective, there are some instances where it is not a good idea to use it.

As tanking slurry is non-breathable, it makes it hard to apply certain finishes on top of it. This includes the likes of paint and even plaster. It could also cause issues when fitting plaster boards using dot and dab.

So, if you are planning to turn a garage or an outbuilding into another room, then it is worth considering your options. However, it might be possible to use these finishes if you apply a bonding compound before applying the final finish.

Most construction materials, such as bricks and blocks are breathable, and therefore you can see damp on the surface. This is because the breathability allows damp to escape through the surface, as well as penetrating in.

If you suffer from severe damp and the surfaces are saturated, then tanking slurry might not be a good idea. Not unless these surfaces have been able to completely dry. This is down to it being non-breathable.

If you apply tanking slurry over heavy damp, it will only trap it behind the surface. This could lead to the damp finding another route into the property. Therefore, you should always look to solve the external cause of damp first.

Where there is a lack of ventilation, such as basements, tanking slurry might not always be the best option initially. The walls and floors of basements can be quite cold. Once you apply it, the surface will be unable to heat up.

With cold walls comes the possibility of condensation and this could lead to further problems such as mould. So, it makes sense to consider ventilation before using tanking slurry.

Alternatives to Tanking Slurry

While it is often recommended to use tanking slurry internally for penetrating damp, there are other options for dealing with damp via tanking.

Tanking membranes (also known as damp proof membranes) come in sheets made of a plastic material. It’s possible to install them on damp walls. They create a small cavity that allows the wall to dry out. Any moisture runs down the membrane and into a channel that runs around the outside of the room. Any moisture is then directed to a gully where the water is then removed. In areas like basements this is then removed using a pump.

A membrane is perfect if you are planning on using dot and dab plasterboard or direct rendering. If you are installing stud work, then a clear membrane can be installed behind it.

There are also other products, such as resin coat waterproof tanking paint. This is a two-part polyurethane coating that you can use on all surfaces. It offers excellent abrasion chemical resistance, and it is fully waterproof.


Tanking slurry is a highly effective solution for penetrating moisture. It’s easy to apply and offers an excellent damp resistance.

In general, tanking slurry is suitable for use in rooms above and below ground level. There are other alternatives, but slurry is a popular option, due to its ease of application. It can easily be done as a DIY damp proofing project.

But it might not always be the best option, especially if you plan to paint or plaster. However, if you do the right research and prepare correctly, it can prove to be a highly effective solution.