What is the best waterproofing material for external walls?

Antonio Neves
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Antonio Neves
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What is the best waterproofing material for external walls?

If you've read this article, you probably want to know about waterproofing external walls, right? This compilation of questions and answers is for you who have infiltration problems on external walls and want to solve them, or for those who are in the construction stage and want to know the correct procedures to avoid the harmful effects of humidity.

If you do not fit into any of these cases, but want to know more about this important subject to ensure a quality construction, you are also very welcome. Therefore, because of our years of experience in the construction industry, we know what the main doubts and questions about waterproofing external walls are. So, we selected and answered the most common ones about this topic to help you in this mission of fighting humidity. Read them all, because, for sure, one of them can be your doubt too. Are you ready? Let's go!

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Why waterproof external walls?

This is a basic question and one that you probably already know the answer to. But it is still very important, which is why it is here. Waterproofing walls is fundamental, firstly, to avoid the occurrence of infiltrations and their consequences, the pathological manifestations that range from the appearance of bubbles, mould and efflorescence. These problems affect not only the aesthetics of the walls, but can compromise the entire structure of the construction and generate problems that require work and money to solve.

In addition, waterproofing external walls, which are more susceptible and exposed to the actions of the weather, increases the conservation and durability of the material, reducing periodic maintenance.

How to stop infiltration in the external wall?

Is your outside wall leaking? First of all, you need to identify what solution your wall needs, that is, to know how to solve the infiltration that is occurring in your wall, you need to identify the problem and the type of coating. I say this because each wall with infiltration requires a solution. For example, if it is a painted wall, you should use BlokSeal, a water repellent that creates a layer that prevents the passage of water and accumulation of dirt.

So, before buying the product, it is important to consult professionals who have knowledge about the subject. If you talk to Blok's team when you have this kind of problem, you will surely use the right product to solve it.

What can be done on the external wall to avoid humidity?

It is very common to think about preventing infiltrations only after they appear. Of course, it is often possible to solve them calmly. However, the most important thing is to waterproof the plaster with BlokMassa ST to prevent the appearance of pathological manifestations on the surface when in contact with water and only then paint. Painting alone helps keep the wall protected, but is not enough to ensure protection against humidity and its consequences. So, the ideal is to waterproof the plaster, and after painting, use BlokSeal water repellent over it. Then you will have a resistant surface.

What is the best product to waterproof external walls?

To waterproof external walls, in addition to waterproofing the plaster before applying the final finish, the best waterproofing material is BlokSeal, a water repellent that can protect the surface against infiltrations and their possible consequences, by creating an invisible layer that prevents the passage of water and the accumulation of dirt. It is indicated for walls that receive various types of finishes, such as paint, textures, exposed brick, projected texture or even if it is exposed concrete. In all these cases, the best product to waterproof external walls is BlokSeal. To learn more, contact Blok.

How to choose the right waterproofing material?

To choose the right waterproofing material to protect external walls, I recommend consulting a professional to help you. The choice is very important because using a product that is not indicated for the purpose you want will not only make you spend money for nothing, but it will not work the way you expect, running the risk of pathological manifestations arising from infiltrations. To avoid mistakes, talk to Blok's team to receive the right orientation to use the right product to waterproof your external wall and avoid facing future problems.

How to apply waterproofing material on external walls?

Applying waterproofing to external walls is very simple. BlokSeal, for example, is the ideal water repellent to apply on exterior walls to prevent infiltrations. First you need to do a good cleaning: the cleaner the surface is, the better the adhesion of the product. After cleaning, it is very important to wait for it to dry completely, because for the ideal result the surface needs to be clean and dry.

Once these steps are completed, all you need to do is apply a coat of the product on the surface with a brush, sprayer or roller, with a thin layer being sufficient to ensure good waterproofing of the substrate. Pretty easy, right? Even so, it is essential to hire a professional team to carry out the service.

Can you apply waterproofing over the paint?

This is a very common question and I will answer it in one word: YES! You can apply BlokSeal over the wall painting. However, this does not dispense with waterproofing the plaster, right? After finishing the wall, you must apply BlokSeal, which is a water repellent able to create an invisible layer on the surface, preventing water infiltration and dirt accumulation, making it easier to clean the walls. BlokSeal also does not alter the characteristics of the material, and does not promote any type of shine on the surface.

How can I paint a wall that has leaked?

If you are going to repaint a wall that is already leaking, you need to remove the mould with water and chlorine and then scrape the entire affected surface, which will remove the paint. Once this is done, you can begin the process of repainting the wall. After drying the paint, you should use BlokSeal, a water repellent indicated to prevent infiltration and, consequently, pathological manifestations such as mold, efflorescence and stains. Thus, the wall will be protected against humidity, ensuring greater durability and conservation.

How to waterproof the wall against the ground?

The wall leaning against the earth is called a retaining wall. Retaining walls need a good waterproofing to prevent the passage of water that causes infiltrations. In this case, the most suitable product is Blok ST, a flexible waterproofing material for positive hydrostatic pressures that prevents the appearance of pathological manifestations resulting from infiltrations. It also has excellent adherence to cementitious substrates, flexibility and waterproofing. If the waterproofing of retaining walls is not done with the right product and in the right way, you will have to face unpleasant inconveniences.

Bonus: how to waterproof outdoor floors

Changing the subject a little bit, if you are interested in waterproofing floors in the external area, we did an article talking exclusively about this. The floors, just like the walls in external areas, are very subject to the action of water and, therefore, should be protected. In advance, on porous floors, such as natural stone or cement floors, you should also use BlokSeal to prevent infiltrations and unwanted consequences, keeping them preserved and with high durability.


We brought this article in a different format about the most common questions regarding waterproofing external walls, which are very exposed to the action of water. These are the most common questions we see in our daily lives, but if your case is not here and you need to know more information about this subject, be sure to talk to the Blok team to understand which product you should use to stop infiltrations on your exterior walls. We guarantee we have the right solution for your problem. Count on us to ensure more quality to your construction works!

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