Can you paint over tanking slurry? What you need to know!

Tanking slurry can be an excellent way of creating a waterproof barrier. It is a low cost and effective way of waterproofing a variety of surfaces. It is particularly good at preventing water ingress, from penetrating damp and rising damp.

Whether you are using it to tank a garage, an outdoor stone shed, your basement, or any other room in your house, such as a bathroom, or kitchen. Tanking slurry is usually a very good option. However, you may find tanking slurry doesn’t provide the decorative finish you are looking for.

Once dried, the slurry is grey in colour and most people will want to add a more aesthetic finish.

There are a variety of ways you can choose to finish your tanking slurry. Such as adding a render, dot dabbing plasterboard over the top and skimming. Another option could be building a stud wall or adding timber battens to the finished tanking slurry and boarding over. If your tanking slurry has been applied in the bathroom or kitchen, you may even want to tile on top.

One question we hear asked regularly, is can you paint over tanking slurry? the answer to this is yes you can. Tanking slurry can be painted over with a water based paint, such as a standard emulsion. This can be applied once the slurry has completely dried after 24 to 48 hours.

At this point a water based emulsion can be added. However, you should avoid using any vinyl based paints for at least the first 6 months.  

Why only water based paints for the first 6 months?

It is recommended you only use water based paints in the first six months, because these paints are breathable. Vinyl based paints, whilst more durable, are not breathable. Due to this, they are prone to blistering and peeling as your tanking slurry cures.

Whilst the tanking slurry will be dry within 48 hours, it is like many other cement-based products. This means it does not completely cure for several months.

During the curing process, the silica in the tanking slurry, will slowly fill pores in the surface it has been applied to, as well as the slurry itself. this process is filling pores that will have been previously filled with small amounts of air.

As the tanking slurry fills these small gaps with silica, this increases the waterproof effect. However, the air that was previously in these pores is pushed out by the silica. Obviously, the small amounts of trapped air need to go somewhere.

When using a breathable, water based paint the air can easily escape. However, something like a vinyl paint will be far less breathable. This means instead of releasing the air, the paint will start to blister and peel from the surface.

The good news is, once your tanking slurry has completely cured, you can paint it with pretty much any type of paint.

How good will the finish be?

The one thing you should consider when painting straight on to tanking slurry is the finish. Once the tanking slurry dries, it does tend to have a slightly textured finish. This means that the surface is not completely smooth. If you do desire a completely smooth finish, then you may want to apply an additional surface prior to painting. as we mentioned previously, you have a few options here. These include:

• Rendering
• Skimming plaster straight onto the tanking slurry
• Dot dabbing over the tanking slurry and skimming – To read our article on how to dot dab over tanking slurry click here
• Building a stud wall and boarding and skimming.
• Adding battens to the wall. Again, this can be boarded and skimmed over.

As you can see most of these involve finishing your surface by skimming with plaster. Obviously, this is a skilled task and not something everybody will be comfortable with. With that said, there is another option If you don’t want to hire a plasterer.

The other option is you can use taper edged boards. This will allow you to simply fill the tapered edge where the boards join. This does not need to be as neat as skimmed plaster and once it has been applied, you can simply sand to a smooth finish.

Following this you can simply paint directly onto the boards. This will give almost the same finish as if the walls had been skimmed. The advantage here, is you do not need to pay a plasterer to come and finish the job for you.

Obviously, if this is a basement or a garage, then a smooth high quality finish may not be as important. However, this does give you a few options to consider.

If simply painting straight onto your tanking slurry is sufficient, then a couple of coats should be enough to finish the job.

Can you paint over tanking slurry with masonry paint?

One final option that is worth considering, is a masonry paint. These types of paint can offer a level of waterproofing all by themselves. They are also designed to be extremely breathable. They are designed to stop water from permeating the surface, while still allowing trapped moisture to evaporate.

Most masonry paints also provide a thick, smooth finish, which can really help to improve the finish of your tanking slurry. Finally, most good masonry paints come in a variety of colours, so you are not just stuck with white or grey, which is the colour you will get with just your tanking slurry.

If you want to learn more about the best masonry paints on the market click here

Conclusion

Here at thedampbuster.com we are a big fan of tanking slurry. It is an extremely high quality and affordable way of waterproofing surfaces. It is also extremely simple to apply, meaning that anybody can do this as a DIY project.

The one thing we have found though, is there is a lot of confusion when it comes to what you can do after the slurry has been applied.

Whether you can paint over tanking slurry is a question we see asked quite a lot, but not really answered that well. Hopefully, this article has given you a better idea of the do’s and don’ts when it comes to painting over your tanking slurry.

Essentially, you can paint over your tanking slurry with almost any paint that is available on the market. You just need to remember, initially you should only really use water based paints.

Try to avoid using any vinyl based paints for at least the first six months. This way, you will avoid any issues and have a painted surface that should last for years.

To learn more about our favourite tanking slurry and read a real case study where we used it click here