How to plaster aerated concrete walls. How to plaster aerated concrete inside a house. Features of finishing aerated concrete walls

Aerated concrete is a cellular type of concrete and has a porous structure. Therefore, buildings made of aerated concrete blocks easily absorb moisture. Accordingly, for greater resistance to bad weather, the material requires protection. Among the most common methods is the use of plaster. Let's take a closer look at the features of plastering aerated blocks, where to start, what tools are required, what finishing technologies exist using this method.

When to start finishing aerated concrete walls

The main distinguishing feature of aerated concrete is its increased hygroscopicity. Moreover, if the structure gets wet, when the temperature is above zero, negative consequences can be avoided - it will simply dry out, everything will be fine, but if water gets into the pores of the stone in winter, it freezes, accordingly, it expands, and cracks may appear.

Considering this, it would seem that the sooner the walls are plastered, the better. But this approach is wrong. It is ideal to carry out these activities for the next season, when the surfaces are completely dry after laying. Drying time depends on what mortar was used for laying. For example, a seam made with a concrete-sand mixture will take longer to dry than where the adhesive mixture was used, since it is much thicker.

Another condition for finishing walls made of aerated concrete, which is recommended to be observed to achieve a high-quality result, is the need to do everything in warm weather. Experts call the optimal time March-October, when the air temperature is above zero. If this is not possible, it is necessary to at least coat the stone with a primer and cover it with plastic film, so that it will stand without losing its properties until it is completely finished. A deep penetration primer will most effectively reduce water absorption.

But sometimes there is no opportunity to postpone finishing work - it is necessary to carry it out immediately after the completion of the construction of the walls of the building. Here experts recommend paying especially close attention to the composition of the solution. It must have good plasticity and vapor permeability, then moisture can escape freely.

Which side to start finishing a gas block building from?

There are three options for where to start covering aerated concrete block walls. Each has its own characteristics, and only one is considered correct. In particular, you can start:

1. outside;
2. from the inside;
3. simultaneously from both sides.

Experienced builders recommend starting to plaster the outside only when the home is located near bodies of water. The primary task here is to protect aerated concrete from water and wind. Under other circumstances, the method of processing from the outside is not suitable - if you plaster the stone from the outside, all the moisture will go inside the house, which can cause cracks to appear, and the drying process of the joints at the end of the masonry will be significantly delayed. In addition, the stone itself may begin to deteriorate. Plastering aerated concrete walls indoors will help avoid the above problems - this method is considered the most preferable due to its effectiveness. The third method is considered the most unpopular method of finishing walls made of aerated concrete - despite the good vapor permeability properties, having “blocked” moisture on both sides, it will have nowhere to go, which sooner or later will lead to peeling of the finishing mixture from the block itself, and subsequently even destruction of the latter.

Sequence of work

Plastering aerated concrete blocks contains three stages. Before plastering aerated concrete, it is necessary to apply a special primer with a brush or roller, intended for building materials that absorb moisture well. The greatest effectiveness is achieved by applying the solution evenly, that is, there should be no dry spots. After completing this stage, the primer should be absorbed and dry.

At the second stage, a special reinforced mesh that is resistant to alkaline components is secured using self-tapping screws. The mesh is fixed at a certain distance from the stone - there should be free space between them.

The final, third stage is the actual plastering of aerated concrete walls. Here it is important to choose materials whose vapor permeability properties are higher than those of aerated concrete itself. You can increase the service life of the surface while maintaining its attractive appearance after a year by covering it with a water repellent.

How to plaster - requirements, nuances

Plaster on aerated concrete will be of the highest quality; it will not have to be re-done in a short time if the composition of the mixture meets certain requirements and the packaging contains special markings. Among other things, it should be characterized by:

1. resistance to cracking, drying out, and fading;
2. increased ductility without sacrificing strength;
3. good adhesion to porous types of concrete;
4. water-repellent properties;
5. high level of vapor permeability.

Compliance with such criteria is especially important when used outside the building.

Even taking into account the large number of different types of modern plaster mortars, only a few have these characteristics, so the following are most often used when working on aerated concrete.

Silicone plaster for aerated concrete has the most advantages. It is resistant to adverse weather conditions, has good vapor permeability, water repellency, and is easy to apply. This type has no disadvantages in operation, except for its high cost, which is nevertheless compensated by the long service life of the coating.

Second place belongs to silicate plaster for aerated concrete, characterized by a suitable level of vapor permeability and low water absorption. The main disadvantages are a small color palette plus the loss of the original attractiveness of the appearance of silicate when exposed to dust.

In third place is cement-based plaster with lime. It also has the necessary qualities to cover this type of structure.

Often in such houses a gypsum mixture is also used. Its advantages: it dries quickly, subsidence is excluded, there is no need to apply a finishing layer of plaster, in addition, you can make the surface as smooth as possible. However, the solution has its drawbacks. These include average vapor permeability characteristics, susceptibility to rapid getting wet from precipitation, and, in addition, stains may appear during its operation.

In addition, acrylic solutions are used for processing. Their quite significant advantage is strength, but we must also remember the disadvantages - low fire resistance, which is why they are used only in certain rooms, and a relatively low level of vapor permeability. To prevent condensation from accumulating in the pores of aerated concrete, experts recommend using additional ventilation or internal waterproofing.

Having studied the characteristics of all the materials presented, everyone can independently choose how to plaster aerated concrete.

Tools used

Plastering walls made of aerated concrete is carried out using tools used when processing other surfaces. Knocking off protruding parts of the walls, making them more smooth, and installing notches where they are needed is done with a plaster hammer or hatchet. The deep penetration primer is applied with a special brush (mack brush). You will also need a plumb line (it helps install beacons for covering the desired surface with the solution), a building level, a square, metal scissors, a hammer drill, a hacksaw, and other standard tools. Regarding beacons, there are several options. The first is to purchase specialized metal beacons at a hardware store; fortunately, the choice of them is now quite wide.

The second, “old-fashioned” method is to use available means: even blocks of wood, pipe scraps, and other suitable “parts”. Thanks to the beacons, the plane is perfectly flat and the angles are correct. The listed tools will be useful if plastering aerated concrete walls is done manually.

Faster, uniform application can be achieved with special equipment. The method is more financially expensive, but this is fully compensated by the quality of the final result: thanks to plastering under pressure, the bonding of the mortar to the surface of aerated concrete is quite strong.

Coating technology

The technology for finishing walls with plaster for aerated concrete is quite simple - it is performed in four steps:

1. preparatory stage, where, before plastering the aerated concrete, it is leveled, thus reducing the consumption of the solution;
2. padding;
3. covering aerated concrete walls with a thin layer of plaster, which will then serve as a base when securing the reinforced mesh;
4. mesh reinforcement (prevents cracks).

For reinforcement, metal or fiberglass mesh is used. Moreover, when installing it, special attention must be paid to windows and doors - places where the load is most significant.

Having secured the mesh, the surface is covered with a finishing layer of plaster, and when the coating dries, the so-called grouting is performed, that is, the surface is eliminated from unevenness, roughness, and other minor defects.

Features of finishing aerated concrete

When starting to cover aerated concrete with plaster mortar, you should take into account the characteristics of this material. First of all, experts recommend avoiding the traditional combination of cement and sand. The corresponding coating can crack and fall off over time, and it also contains a lot of water, which has a destructive effect on the walls themselves.

When plastering aerated blocks, a prerequisite is that all products are intended specifically for the cellular material.

It is important to begin work on the external cladding of the facade when all “wet” internal work has already been completed, then the formation of condensation inside the walls can be avoided. Moreover, the thickness of the plaster layer inside the building should be twice as large as the outside one, otherwise water vapor will remain inside the blocks and they will become damp. This is the only difference between carrying out this work inside and outside - the technology itself remains unchanged.

Thus, we see: with all its advantages, the building material is still quite finicky and requires special treatment. And in order for it to preserve its beneficial properties to the maximum, it is necessary to take a number of measures. But if you follow the above recommendations, it will prove to be a very reliable material, will last a long time, and your home will be cozy and comfortable.

Video: Plastering aerated concrete, preparing the base

Video: Putty and plaster of aerated concrete

Internal and external aerated concrete plaster must have optimal parameters, protecting the walls of the structure from destruction and cracks under the influence of external influences. There are several basic options for finishing mixtures that will improve and maintain the quality of the base. The correct application technology will ensure a long service life and decorative appearance of the coating.

Aerated concrete has good thermal insulation properties and a high degree of vapor permeability due to its porous structure. Proper finishing of aerated concrete will help preserve the quality of the material, preventing the accumulation of condensation and the occurrence of mold.

In this article we will answer the main question, how to plaster aerated concrete outside and inside the house.

Aerated concrete blocks Source sevparitet.ru

Basic requirements for plaster

It is worth noting right away that it is not recommended to apply ordinary plaster to a house made of aerated concrete blocks. Primarily because standard sand solutions are high-density, this leads to poor adhesion when applied to aerated concrete blocks and the rapid appearance of cracks.

Adhesion(from Latin adhaesio - adhesion) in physics - adhesion of the surfaces of dissimilar solid and/or liquid bodies.

The plaster should maintain an optimal microclimate inside the building, protecting the walls from moisture. Therefore, you should choose mixtures with a vapor-permeable base. Otherwise, the steam coming out of the house will get stuck inside the walls, since the plaster will simply block its exit to the outside. Thus, moisture will begin to accumulate in the walls, which will ultimately lead to their destruction. Of course, nothing will happen to the house in a few years, but in six to eight years the almost irreversible process of destruction will begin.

Plaster for aerated concrete should be:

• resistant to external weather influences;
• have good adhesion (adhesion to aerated concrete);
• resistant to sudden temperature changes;
• high degree of compressive strength (protection against cracking);
• vapor permeable;
• moderately dense;
• improving the thermal insulation of walls;
• have a decorative appearance.

When choosing plaster for aerated concrete, you should not ignore any of the points listed above.

Applying plaster to a house made of aerated concrete blocks Source emupauto.ru

The absence of facade finishing of aerated concrete structures will lead to darkening, deformation, and peeling of the surfaces of the blocks.

Types of plasters suitable for aerated concrete blocks

The choice of plaster mixture for aerated concrete primarily depends on whether you are going to cladding the walls from the outside or from the inside. Based on the type of application, plasters are divided into external and internal.

As you understand, external plaster is intended for finishing facades. Since here it performs protective functions, its strength, moisture resistance and thermal insulation indicators should be higher.

Internal mixtures are intended for finishing indoor walls, so the presence of moisture resistance in the characteristics of these plasters can be ignored, with the exception of cases of wall cladding in the bathroom. Due to the lack of resistance to moisture, internal mixtures are much cheaper than external ones.

Applying a finishing layer of plaster to aerated concrete Source o-cemente.info

Popular plasters for aerated concrete

Mixtures for finishing facades made of aerated blocks are divided according to the type of composition into:

• lime-cement;
• acrylic;
• silicate;
• silicone.

Lime-cement mortars quite durable and at the same time vapor-permeable, because their main component is lime, which replaces sand. The low level of water resistance, elasticity and limited choice of color palette of the material can be eliminated using various additives. Modern ready-made mixtures contain special fillers that improve the properties of the coating.

Acrylic It is advisable to finish a building made of aerated concrete only if there is high-quality internal insulation of the walls. This plaster cannot boast of good vapor permeability, but as a decorative finish, it is durable and reliable.

Silicate plaster for aerated concrete is produced on the basis of liquid potassium glass. The coating has good moisture resistance, vapor permeability and durability. The silicate solution is easy to apply. The finishing layer is resistant to dirt and abrasion, providing a decorative finish for a long time (more than 25 years). The problem with silicates is the limited choice of colors.

Leveling walls with silicate plaster Source lineyka.net

Silicone mixtures contain resins and organosilicon polymers. The quality characteristics of the material are optimal for creating a durable coating. Silicone-type plaster retains elasticity after application, which ensures the absence of cracks on the surface even when the blocks shrink. It is important to note the special decorativeness of the finishing; thanks to special fillers and color variations, you can give the facade an original look.

Silicone plaster can undoubtedly be called a leader among others; it has all the advantages of silicate compounds, moreover, it is durable and looks great. But the price of silicone mixtures is much higher than others.

Most popular manufacturers

The building materials market is saturated with a huge number of plaster mixtures of various brands for finishing aerated concrete surfaces. Popular compositions have optimal characteristics for the work.

Applying plaster to the interior walls of a gas block house Source obustroeno.com

Ceresit CT 24. The mineral composition of the mixture gives the solution plasticity. The material is easy to apply. The coating can withstand up to 100 cycles of low temperature influences. It is recommended to paint after complete drying (after seven days).

CERESIT ST 77. The acrylic type of the mixture is used for facade finishing, ensuring the strength of the coating with a fairly thin layer of application. The material is frost-resistant and resistant to external influences. Used when there is waterproofing and ventilation inside the house.

Founded by Startwell T-21. Cement-lime plaster is frost-resistant and has a sufficient level of adhesion. The resulting coating is resistant to shrinkage and moisture.

Video description

Watch the video comparison of facade plasters for aerated concrete:

Baumit Silicone Top. A high level of adhesion and ductility is achieved thanks to the base of the mixture - silicone resins. The coating remains decorative for a long time due to its dirt-repellent properties. Wide choice of material color palette (up to two hundred shades).

Weber.pas silicone. Mixture based on silicone emulsion. It is possible to select the appropriate grain size. Optimal resistance of the material to moisture, temperature, and dirt.

Baumit Silikat Top. Silicate type of plaster. The coating is durable and has good vapor permeability. The composition has different grain sizes and up to two hundred tinting variations.

Priming the surface before plastering Source en.aviarydecor.com

Internal plaster of aerated concrete walls

Internal work on plastering walls made of aerated blocks is carried out with gypsum solutions with various additives. Composites in the form of perlite and marble chips will increase the decorative effect of the finish. There is the possibility of painting the composition in various colors.

Gypsum mixtures without additives have the required level of vapor permeability, which allows the plaster to be used as a base for wallpapering. Standard sequence of work:

• elimination of irregularities and chips on the surface of the walls;
• removing dust and applying the first layer of solution;
• installation of reinforcing mesh;
• applying the second layer.

After complete drying, you can glue wallpaper, paint the walls, or apply a third, decorative layer of plaster.

Interior work is carried out only subject to the preliminary application of a waterproofing compound and priming.

Interior wall plaster Source poradnuk.com

External plastering of aerated concrete walls

Plaster for façade aerated concrete can be applied using various technologies: thick-layer or thin-layer finishing. The sequence of work includes:

• mandatory preparation of wall surfaces, leveling;
• priming (compositions based on acrylate siloxane);
• applying a thin layer of solution - the basis for attaching the mesh;
• reinforcement (protection against cracks);
• leveling the finishing layer;
• second layer of coating (formation of a smooth, even surface);
• finishing layer of plaster, grout.

A year after completion of the facing work, it is recommended to apply a water-repellent solution. Thanks to the treatment of the facade with this composition, the moisture-proof and water-repellent properties of the coating are increased.

Features of plastering walls made of aerated blocks

Proper execution of the work must take into account the characteristics of the material of construction. Aerated concrete blocks may have differences in structure. Sawn options have an open, pronounced cellular structure and do not require special preparation for finishing.

The formed blocks are covered with a hydrophobic layer with a closed pore structure and require additional processing. Grinding the surfaces with a wire brush will help improve the adhesive properties of the material.

Video description

Watch the video of the process of applying plaster to a house made of aerated concrete:

It is also important to remember the rule of increasing the degree of vapor permeability from the inner layer to the outer surface. The façade finish should be twice as thin as the interior coating.

It is strictly not recommended to carry out plastering work on aerated block surfaces earlier than 6 months after the construction of the walls. The structure must dry completely, getting rid of excess moisture accumulated during laying of the material.

Plastering on reinforcing mesh Source bg.decoratex.biz

Optimal conditions for applying plaster

External plastering of aerated concrete must be carried out under certain conditions. It is important to first complete interior work with high humidity levels. The load-bearing structures of walls made of aerated blocks must be completely dry, not exceeding 27%. Otherwise, high humidity will cause adhesion failure and lead to peeling of the finishing layer of the facade.

The optimal time for finishing the interior of the house is spring, the façade of the building is the end of summer.

External temperature conditions for work must correspond to +5-+30°C, with air humidity not exceeding 80%. If it is necessary to perform finishing at low temperatures, it is recommended to use a special deep-penetration primer composition until the onset of acceptable weather conditions.

Carrying out the work correctly will help avoid peeling, cracks and defects. It is forbidden to apply the coating in hot weather, under direct sunlight and in windy weather.

Plastered facade of aerated concrete house Source econet.by

Conclusion

Choosing a high-quality solution for plastering aerated concrete structures will help improve the performance characteristics of the material and create strong and durable surface protection.

The topic seems to be “hackneyed”, I’ve read a lot, I have a lot of doubts, please advise, respected practitioners and specialists in the field of interior decoration.
Walls of the house: gas silicate block D 600, Venti Bats insulation on the outside, ventilation gap and half-brick cladding. Need plaster on the inside, wall area 230 sq. m. In order for the house, as they say, to “breathe,” what is the optimal way to plaster based on this and from an economic point of view?
I saw two options:
1. Lime-sand dry mixture produced by a local brick factory at a price of 2500 rubles per ton; they could not find out the consumption, they only said that cement would need to be added. In total, I assumed a consumption of 10 kg of dry mixture per 1 sq. m. meter, received a quantity of material of 2300 kg and costs at 230 sq. meters of walls cost 5,750 rubles. Plus cement, I think in the end it will cost 8-10 thousand rubles.
2. Gypsum plaster, sold in Leroy for 200 rubles 30 kg (bag) of the “Stone Flower” brand and for 300 rubles 30 kg of the “Volma” brand. For 230 kg at a consumption of 9 kg of dry mixture per square meter indicated on the bags. meter (in my opinion, the walls are quite smooth, this consumption is indicated on the bags with a layer of plaster thickness of 1 cm) it turns out that you need 2070 kg, i.e. 69 bags. Accordingly, “Stone Flower” gypsum plaster will cost 13,800 rubles, “Volma” will cost 22,350 rubles.
More introductory notes: the house will be without heating, but will have windows for another 2-3 years, I plan to plaster it for painting with water-based paints, plasterers in the region are asking 280 rubles per sq. m. meter of plastering work plus another 160 rubles with putty for painting, a total of 440 rubles per sq. m. meter of wall for painting, my wall area will cost me about 100 thousand rubles.
Dear colleagues, questions:
1. What is the difference between gypsum plaster for 200 rubles a bag and 300 rubles? In terms of reliability, performance characteristics, durability after completion of work, comfort in the future, or simply ease of application, I want the house to “breathe.” I don’t care about ease of application, because I will pay for the final result?
2. Is it better to use lime-sand plaster or gypsum plaster? How much does gypsum really provide a better microclimate in the house than lime-sand-cement plaster? First of all, I am interested in a comfortable microclimate in the house in the future; if I calculated correctly, then the difference in the cost of these two materials is not critical, because the main cost here is in the work. Or is the consumption indicated by the manufacturers on the bags underestimated, everyone writes that gypsum is much more expensive? The house, as indicated above, will stand without heating for 2-3 years, I read that gypsum plaster can swell from humidity.
3. Who has had experience - how many 30 kg bags of dry gypsum plaster will actually be needed for 230 sq. m. of mid-level walls?
4. Is it still necessary to prime the gas block before plastering work and with what, or is it enough to wet the walls with water? Should the plaster be primed before applying putty or not?
5. Regarding plastering work: 280 rubles per square meter. meter of plaster “for lighthouses” and plus 160 rubles of putty for painting - what should you pay attention to when working for this money, how many times should they putty according to the rules?
6. Another option was born: the first floor is definitely for painting, and to save money, just plaster and putty the second floor for the same 280 rubles. meter in a compartment, then cover it with non-woven paper-based wallpaper for painting (not vinyl, as they said in the store, non-woven wallpaper “breathes”). Maybe someone has done this and will give comments on this idea?
Of course, I wrote a lot, but with the goal of getting competent answers. Thank you all in advance for your help.

Internal and external plastering of gas silicate blocks is one of the most common methods of finishing walls made of this material. When carrying out this work, many people forget that they follow a slightly different approach than conventional brick or monolithic concrete surfaces.

Since houses made of aerated concrete easily absorb moisture, they must be plastered.

Plaster errors

For example, a case that needs to be considered to make it clear what the consequences may be if there are errors in finishing walls made of aerated concrete.

For exterior finishing, the use of conventional cement-sand mortar is simply unacceptable. This is all connected with the same vapor permeability and leads to a violation of the main rule, which states that any multi-layer breathable wall must have a vapor permeability that increases from the inside out from layer to layer or be at least comparable.

The plaster mixture for walls containing is sold in the form of a dry powder with special additives that help meet the following performance characteristics:

If you leave a house made of aerated concrete over the winter without plastering, then next year it will “delight” with a network of cracks.

• vapor permeability (the most important factor);
• water resistance (no less important and protects the blocks from getting wet);
• good frost resistance;
• high adhesion (ability to adhere tightly to blocks);
• resistance to mechanical damage;
• elasticity (prevents the appearance of cracks during precipitation and during the process of expansion and contraction during temperature changes outside);
• heat resistance (increases the ability to withstand the effects of fire, i.e. increases the fire safety of the entire structure).

Before starting plastering work, preparatory work is required. Clean the wall surface from dust, dirt, bitumen stains or old layers of plaster or paint.

The plaster solution for gas silicate blocks must be prepared strictly following the instructions on the packaging. To begin with, the mixture can be poured into a container of sufficient size, observing the proportions in terms of quantity and weight. For 1 kg of mixture, 0.20 liters of water is usually required. It is very important to correctly add the required amount of water, since it is undesirable to dilute plaster mixtures with too thick a consistency, and it is simply inconvenient to use plaster that is too liquid. The mixture of ideal consistency should be somewhat like a cream.

You can mix plaster mixtures manually, but it will be more convenient, better and faster if you use a drill with a special attachment.

Step-by-step instruction

Walls made of gas silicate blocks should be plastered in the following sequence:

The finishing of the facade occurs in three stages - priming, plastering and painting.

1. The wall is coated with a special primer, which is made from acrylate siloxane, which has strengthening and hydrophobic properties.
2. A fiberglass mesh is attached to the wall, which is resistant to alkali solutions and has a surface density of 200 g/m³. It should have a high resistance to tensile loads and should not stretch.
3. Having previously installed the guide beacons, the solution is evenly applied to the wall. This is done using a plastering unit, trowel or ladle. The thickness of the plaster layer should not be more than 1.5 cm. If the plaster mixture is applied in 2 layers, then each layer should be within 7 - 9 mm.
4. The still fresh plaster is leveled using a plaster lath, the excess is removed with a wooden float.
5. After letting the surface dry a little, it is rubbed down.
6. Not earlier than after 48 hours, the walls are covered with specially designed vapor-permeable paints, for example, ATLAS ARKOL S or FASTEL.

All tools must be thoroughly rinsed with water immediately after finishing work, otherwise the remaining plaster will harden and removing it will take a lot of time and effort.

The quality of the plaster layer is checked using a long strip (from floor to ceiling), which is applied in several places both horizontally and vertically. The presence of irregularities and protrusions relative to the plane of the rack is immediately noticeable. The permissible error is 5-7 mm, since it is invisible to the ordinary eye.

In order to increase the service life of the facade, the finishing coating can be additionally treated with a layer of water repellent. But before applying, you need to wait until the house is as dry as possible. That is, this can be done 1 - 1.5 years after the completion of all finishing work (external and internal). The applied layer of water repellent should be as thin as possible.

To summarize, it is clear that plastering aerated concrete is not cheap, as many people think. Saving on materials can lead to disastrous consequences, as was shown in the example at the beginning of the article. Here we can confidently say this: it’s not about bad building materials, but about their incorrect and inappropriate use. And if a decision is made to plaster gas silicate concrete, then it is necessary to do this using only materials suitable for this particular work.

External and internal plastering of walls made of gas silicate blocks has become a widespread type of finishing work due to the widespread use of this material in the construction of individual and multi-apartment residential buildings. Gas silicate products provide good thermal protection of premises and significantly reduce the load on the foundation, but the technology of plastering requires knowledge of the purpose and behavior of each component involved in this process. Otherwise, the strength of the coating on the plastered wall will be less than expected.

Subtleties and tasks of gas silicate plaster

The task of properly plastering walls is important specifically for gas silicate blocks, because due to their specific structure they have a very high degree of vapor permeability. Saturation of the entire mass of material with water vapor during the season of severe frosts will lead to the destruction of its structure by the expansion of ice crystals.

The brand of plaster used should reduce the intensity of the process to an optimal value that does not pose such a risk, and establish a comfortable balance of humidity and temperature in the house.

As an example, we can give the characteristics of a typical plaster mixture, summarized in the following table:

On the packaging of its products, the manufacturer indicates recommendations for the possibility of application to certain surfaces. Usually on the front side it is indicated in large print whether the composition is intended for plastering.

Fundamental points

In order to perform its function fully, certain requirements must be met. They are associated with the characteristics of the material, which appear even after it is laid in the wall structure.

Depending on the planned completion date of all construction work, the following points are taken into account:

1. The permissible humidity, which is inherent in gas silicate products at the exit from the production line, is up to 30%. The drying procedure for the entire block takes at least 1 cycle of operation, so after the first winter the blocks tend to develop large or small cracks. Before finishing work begins, the laid out frame of the building is kept, if possible, for about 1.5 years. If such a period is unacceptable, then it is better to first plaster these walls inside the house so that the moisture has the opportunity to evaporate through the outer area accessible to air movement.
2. The appearance of cracks can also be caused by shrinkage of the foundation. Before plastering the walls, you need to let the house sit for 1 - 2 cycles of freezing and thawing of the soil. Otherwise, the cracks in the plaster will go deep into the base material of the walls and cosmetic rubbing will no longer be enough.
3. Air circulation from the outside is ensured by using the operational capabilities of the ventilated façade of the house. Facing with various types of panels (stone, wood, siding) or using well brickwork creates conditions for the constant removal of moisture vapor through a specially left air gap.
4. You should not use moisture-proof extruded polystyrene foam as external insulation. It will retain condensation at the border of contact with the masonry.
5. Problems of high humidity in individual rooms in a residential building should not be solved only by plastering blocks and selecting a composition with exceptional characteristics. In the future, the walls in this room can be additionally protected with moisture-resistant tile adhesive or finishing coatings (tiles, waterproof paint or vinyl wallpaper).

One of the options for the appearance of defects on gas silicate blocks 1-2 years after installation is visible in this photo:

The reason for the destruction is that a material such as aerated concrete needs reliable protection from aggressive environmental influences and destructive forces:

• mechanical damage;
• precipitation;
• ultraviolet;
• direct contact with water;
• weathering.

The porous material intensively absorbs water, which, expanding when heated or freezing into ice, breaks the cellular structure.

The means of protection will be waterproofing the base, covering with a layer of plaster (outside and inside the building), and installing external thermal insulation.

The effective operation of gas blocks is largely determined by the consistent and high-quality creation of an internal vapor-tight barrier made of plaster.

Stages of plastering aerated concrete

Plastering walls made of gas silicate blocks should begin by thoroughly impregnating the entire area of ​​the wall with a special primer. Unlike, which has a closed porous structure, during production the material develops open pores, since fine aluminum chips are added to the base solution as an additive. It is the main gas generator when reacting with lime present in the liquid mixture.

The purpose of the primer in this case is to close surface pores, prevent active absorption of moisture from the plaster solution (give it sufficient time to harden evenly), and ensure high adhesion for strong adhesion to the surface.

Primer impregnation can be applied generously without gaps over the entire wall using a sprayer or roller, as in this photo:

Attempts to replace special compounds by simply spraying with water, as a rule, give poor results in terms of the strength of the resulting plaster - the material absorbs moisture very quickly, and if it is soaked in a large amount of water, it will not give it back.

Reinforcement

To prevent subsequent cracking of the plastered surface, to maintain the integrity of the monolithic seamless solid mass - this is the task facing. Construction mixtures based on cement or gypsum have a pronounced alkaline environment, so fiberglass must be resistant to this category of substances.

When laid, gas silicate blocks form a fairly flat plane, which, if necessary, can be easily further leveled with a float with an abrasive attachment, so the sufficient thickness of the plaster mortar layer is from 2 to 7 mm. A flat mesh is placed in it.

On walls of a large area (height), it may be necessary to level the surface with plaster vertically or horizontally. Then it is advisable to choose a more durable coarse mesh, as in this photo:

A flat mesh is pressed onto a thin (1 mm) layer of plaster or glue, which is covered with another layer of plaster mixture. The total thickness of the resulting coating should not exceed 1 cm.

Advice on how to determine the need to reinforce internal plaster walls made of gas silicate blocks is discussed in this video:

Requirements for plaster application technology

External plastering work on blocks begins only after complete finishing of the wall finishing work from the inside of the house, completion of wet mortar processes for installing floor screeds, plastering, and puttying work.

All moisture evaporating during these operations comes out not so much through ventilation and other openings (drafts are harmful here), but is actively absorbed by the surrounding materials and then tends out through the pores of the gas silicate walls.

If the walls on the facade of the building are plastered prematurely, then the external protection made in the cold season will accumulate at the border of the plaster and aerated concrete, freeze and tear off the plaster layer (shooting, peeling).

The decision on how to plaster gas silicate is made taking into account the following factors:

1. Cement-sand mortar is poorly suited for this purpose for the following reasons: poor adhesion due to rapid loss of water (a primer will not always help); a significant reduction in the vapor permeability of aerated concrete (disturbance of the microclimate inside the house). For exterior finishing, the use of cement-sand mixture prepared according to the usual recipe is simply unacceptable. This leads to a violation of the basic rule - the vapor permeability of a multilayer wall should increase from the inner layer to the outer one or be a comparable value.
2. A solution of dry plaster mixture (for gas silicate blocks) must be prepared strictly according to the manufacturer’s instructions indicated on the product packaging. The mixing container is of sufficient size, maintaining the recommended proportions and water temperature with precision. The amount of added water is strictly metered, since subsequently it is undesirable to dilute a swollen plaster mixture with an overly thick consistency that has been kept for the required time, and a solution that is too thin will drain. It is better to stir evenly until a homogeneous mass is done with an electric drill with a special attachment.
3. In addition to strength, for external plasters you should pay attention to frost resistance and elasticity. Changes in external temperatures create the preconditions for the appearance of cracks in monoliths that are too rigid. We should not forget about the flammability class of the material - fire resistance is an important indicator of home safety.

The approximate consumption of necessary materials and approximate prices for determining the budget structure are given in the table:

The approach to plastering gas silicate blocks inside is simpler - for this purpose there is a wide range of gypsum compositions for interior work, which do not need to resist weather conditions.

You should not abandon the procedure of plastering the room from the inside, limiting yourself to making a thin coating of one putty. The effort expended should form a complete wall covering.

Saving through cheap materials or their quantity often leads to bad consequences. We can confidently say that the problem is usually not in poor building materials, but in their improper use. If there is a need to plaster gas silicate blocks of external walls, then this must be done using only materials specially designed for such types of work.