Facade waterproofing

Many building materials used for building and finishing the facades of buildings have a porous structure, which contributes to the abundant absorption of moisture from the atmosphere. When it evaporates (under the influence of solar radiation, for example), the salts that make up the water are deposited on the walls and appear as deposits that spoil the building's appearance, called “efflorescence”.

In order to protect the walls, the facade is hydrophobized using special water-repellent compositions (water repellents) to protect the porous surfaces of the facades from moisture penetration into them. Such compositions are effectively used to protect (waterproofing) facades made from the following moisture absorbing materials:

• brick and stone;
• aerated concrete blocks;
• cement-sand plaster;
• special facade tiles;
• tile or wood.

In addition to preventing the formation of "efflorescence", treatment with water repellents allows you to:

• to protect the facades from fatty contamination, as well as from the damaging effects of precipitation;
• improve the insulating properties of materials whose sensitivity to seasonal freezing and thawing after processing is somewhat reduced;
• protect wall surfaces from mold and mildew;
• improve the appearance of facades, which after processing look much better than before it (due to the greater expressiveness of color and texture).

At acquaintance with technologies of protection of facades from humidity it is necessary to distinguish water repellency from waterproofing known to all of us. The main difference between these two procedures is that with the hydrophobic protection of surfaces, their vapor permeability is maintained at a given level, thanks to which the building breathes (as they say, its walls allow steam and gases to pass through). A completely different picture is observed when waterproofing surfaces, after which the pores of the coating are completely isolated, losing access to ambient air.

The need for hydrophobization usually arises in situations where there is a repeated, but short-term effect of moisture on the surface (for rainfall, for example). In the same cases, when the structure is exposed to moisture constantly - as a rule, the waterproofing method is used.

Types of protection

The known methods of hydrophobization of walls involve the use of two methods of processing them with protective compounds: surface and bulk.

In the first case, a special composition is applied directly to the surface to be protected, whereas the volume hydrophobization is carried out at the stage of preparation of the finishing material itself.

The most effective way is considered the combined use of both of these methods, involving the introduction of water-repellent agents in a solution of liquid finishing material, followed by applying a protective layer directly on the finished (already dried) coating.

With the surface treatment of facades, the protective properties of the deposited compositions are maintained for about 10–15 years, and for bulk and combined, during the entire operational period. In our article, the surface hydrophobization method will be considered as the simplest and often used in practice.

Materials used

Hydrophobization of the facade can be made using various types of impregnating compositions, the most effective of which are materials based on silicone or silicon. Such compositions well protect the walls of the structure from moisture, without disturbing the natural air exchange through the facade of the building. Known silicone water repellents can be in the form of:

• water emulsions;
• organic compounds;
• water soluble blends.

As well as compositions based on silicon compounds, silicone water repellents do not lose their performance properties for quite a long time. During processing, they penetrate into the thickness of the walls to a depth of about 15 mm, as a result of which a polymer film layer forms on their surface, creating an impermeable barrier to moisture. In this case, the coefficient of moisture absorption of the material decreases significantly (for bricks, in particular, this figure can be as high as 20 times).

Currently, manufacturers of water repellents offer a wide selection of colorless and tinted impregnations, some of which allow to obtain various effects (the effect of "wet" brick - in particular). In addition, the composition of such impregnations may include other protective compounds (antiseptics or flame retardants, for example).

Conditions and procedure for applying protective coatings

First of all, we note that it is recommended to apply the simplest protective compounds on a dry surface in one or more layers (their exact amount is selected based on their specific needs) at air temperature not lower than + 5 ° C. In addition, it is undesirable to carry out hydrophobization at high humidity, which is most often observed during periods of precipitation.

Note that the primary impregnation of the facades can be done immediately after the surfaces are coated with the finishing material you use.

Note! Before treating the walls with a special impregnation, it is desirable to prime them first, which will ensure better adhesion of the materials used for this.

To apply a water repellent to the surface to be protected, you can use a conventional brush or spray gun, by means of which the liquid mixture is applied in several layers (at intervals for each hour to dry each layer).

Note! The walls should be processed only after the completion of all types of finishing works, since the water-repellent protected surface can no longer be not only plastered, but also painted.

As an example, consider the features of the organization of such protection on plastered facades.

The protection of plastered surfaces by the method of their hydrophobization is carried out according to the scheme already considered by us, which involves applying a protective compound with a brush or spray gun. In this case, impregnating compositions with organosilicon additives, which not only protect the wall surfaces from moisture, but also significantly reduce the drying time of the plaster (almost twice), are used as water repellents.

Particular attention is paid in this case to the preparation of impregnating compositions of dry mixes, carried out at the place of their use immediately before application.