What is positive and negative pressure?

Do You Know What Negative and Positive Pressure Waterproofing Is?

Do You Know What Negative and Positive Pressure Waterproofing Is?

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What is waterproofing?

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For you to understand about waterproofing by negative and positive pressure, let's first explain what waterproofing is. You must already know that it is an important process for a quality project and for keeping the property preserved and valued, right? But what does this process consist of, anyway?

Waterproofing is the application of a specific product over an area with the objective of making it protected against the action of water. This process causes water to not be able to cross the material and, therefore, avoids problems caused by humidity.

But how do you define the right product for each type of situation? To facilitate this choice, it is recommended to take into account two aspects before making the waterproofing: the type of structure and the form of water pressure. Today, we are going to dedicate ourselves to studying this second aspect, to understand the difference between negative and positive pressure and how waterproofing is fundamental for both cases.

What is the difference between negative and positive pressure?

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When we talk about forms of water pressure, we are referring to positive and negative hydrostatic pressures, but what does that mean?

Positive pressure is the force exerted by water or moisture directly on the waterproofing system, which compresses it against the base on which it is applied.

Negative pressure, on the other hand, is the pressure exerted by water acting in the opposite direction to that of the waterproofing, that is, penetrating through the structure and forcing the waterproofing in order to try to release it from where it was applied.

According to NBR 9575, we have the following definitions:

water under negative pressure: water, whether confined or not, that exerts hydrostatic pressure greater than 1 kPa (0.1 m.c.a), in reverse to waterproofing.
water under positive pressure: water, whether confined or not, that exerts hydrostatic pressure greater than 1 kPa (0.1 m.c.a), directly to the waterproofing.

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impermeabilização pressão negativa e positiva — Negative and Positive Pressure Waterproofing

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Was it possible to understand? Now let's get to what really matters! How to choose the right product for each situation?‍

How to select the product according to the forms of water pressure?

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You must be wondering how to choose the right product for each type of situation, both when there is positive and negative pressure and in this topic we will explain why it is so important to take into account the forms of water pressure when buying the product.

If you are looking for a solution for regions that suffer from positive pressure, such as a slab, swimming pool, Baldrame, underpinning, water tanks, reservoirs and wettable areas in general, the use of waterproofing agents flexible for positive pressure, such as Blok ST, since they will be directly pressed by water against the structure.

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Impermeabilização por Pressão Negativa e Positiva — Negative and Positive Pressure Waterproofing

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O Blok ST It is a waterproofing resin for flexible structured polymer mortar that will surprise you when applied to areas under positive pressure. It is a product that has excellent flexibility, adhesion to substrates, resistance to high positive hydrostatic pressures and ultraviolet radiation.

For areas that experience negative hydrostatic pressure, there are specific products for this purpose. Therefore, it is necessary to keep an eye out when the region is under negative pressure so as not to make a mistake when choosing the product. In this case, the waterproofing against moisture by negative pressure is carried out using products that are less flexible, when compared to those with positive pressure, but with a greater adhesion power, presenting greater resistance to negative water pressures.

The best product suitable for this situation is Block STP, a waterproofing resin for structured flexible polymer mortar, which can be used on any surface subject to negative pressure. In addition to excellent waterproofness, Blok STP has high resistance to negative hydrostatic pressures, excellent adhesion to the substrate and easy application.

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Have you seen how essential it is to prioritize choosing the right product according to the forms of pressure that water exerts on the structure? With that in mind, now let's see the consequences of not choosing the right product and the problems that may appear!

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What if I chose the wrong product?

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In a construction, there are several elements and each of them is exposed to different types of water pressure. For this reason, a waterproofing failure in a building may result from a lack of attention to the possibilities of occurring seepage coming from both positive and negative water pressures as well as from Wrong choice of the product, causing stains, mildew, fungi, molds, and paint peeling.

Therefore, it is necessary to be aware at every possible point of suffering moisture attacks and apply the specific product for each purpose. It's no use knowing that a wall of Arrimo is exposed to moisture if an appropriate waterproofing agent is not applied, as the case may be, for negative pressure, for example.

Choosing the right product for each cause of humidity is essential to avoid problems with seepage and maintain a quality construction!

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Negative pressure moisture treatment

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As we have said, the humidity generated by negative pressure appears when the water is pressurized from the inside out and, if the specific product is not applied, it can cause paint peeling and mold or mildew.

Therefore, carry out the negative pressure moisture treatment The use of the correct waterproofing agent affects not only the appearance, but the structure as a whole.

In addition, to address this problem, it is necessary to verify the different needs that are required, for example, if it is a problem in the basement, it is necessary to verify the foundation structure of the building and also, since the causes of humidity may be different, the products and the way of performing the service are particular and must be evaluated on a case by case basis.

An example of this type of problem is to disregard the negative pressure exerted by the water table in the construction of an inground pool, when applying a waterproofing agent that does not withstand the pressure exerted by the water, which can cause complete detachment of the bottom of the pool, which can cause enormous labor and expenses for repair.
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Today, we explain the importance of negative and positive pressure waterproofing and how choosing the right product can make all the difference and avoid major problems!

We also present our products that are suitable for solving these problems, but if you want to know even more, take a look at our site to discover other solutions for your construction!

Count on Blok and make the best choices every time!