Plastering the gas block with cement mortar. Aerated concrete wall plastering technology

The article popularly talks about widely used building materials, lightweight concrete, the main characteristics and finishing methods using traditional technologies, plastering of house elements.

Aerated concrete wall plaster

Plastering of internal and external structures made of lightweight concrete is the most used method of protection against the effects of external climatic conditions and giving the house an original respectable appearance, as well as internal comfort.

The prevalence of technology is due to the ability to inexpensively and on their own to carry out a set of works on the preparation and finishing of structures and achieve the desired results.

Special characteristics of aerated concrete blocks

Aerated concrete refers to aerated concrete, consists of quicklime, cement, sand and gas-forming aluminum powder. When mixing the components and water, a reaction occurs with the release of gas, forming voids, the number of which determines the weight, density, thermal conductivity of concrete and the scope of use:

• Concrete with a density of 300-400 (kg / m3) is used for thermal insulation.
• Density 500-900 (kg / m3) can be used for the installation of partitions and walls.
• With a density of 1000-1200 kg / m3, concrete is used for the manufacture of load-bearing walls.

Concrete has gained popularity in housing construction due to its properties:

1. Low thermal conductivity allows it to be used as a heat-insulating substance.
2. Frost resistance can reach 150 cycles; among lightweight concrete, only expanded clay concrete has greater durability.
3. High fire resistance.

Of the negative qualities for construction, hygroscopicity can be noted, which means that aerated concrete needs to be coated.

The hygroscopicity of aerated concrete requires insulation from moisture.

Preparation of gas silicate blocks indoors for plastering

In aerated concrete, the amount of cement is up to 60 percent, in gas silicate concrete no more than 14, lime is twice as much, the rest is sand. The percentage is important, because the more cement, the higher the strength, and the base must be stronger than the coating, otherwise it will flake off. That is, the decoration of the house must be done with a lime-cement composition.

When finishing, you need to remember that the base must be stronger than the coating.

The main function of plastering surfaces made of gas silicate blocks is to form a vapor-impermeable barrier and limit moisture absorption. To improve the adhesion of the coating to the base, the structural elements are covered with a deep penetration primer, the first layer is applied generously, preferably with a spray gun, after drying, you need to paint over again.

After priming, given that the base is weak, it is necessary to carry out reinforcement to prevent the appearance of cracks.

The rough layer of reinforcement is made from glue on which the blocks were laid; experienced craftsmen use tile glue for this as a cheaper composition.

The use of glue instead of a conventional solution is associated with polymer additives in the composition, which ensure strong adhesion with a thin layer of the mixture.

After applying a thin layer of glue, 2-7 millimeters thick, a fiberglass mesh is embedded in it, which fixes the blocks and serves as a reliable base for the coating. The mesh is overlapped on the applied adhesive and pressed in with a notched trowel.

It is advisable to start applying the solution in 5-7 days, when the reinforced layer gains strength.

Plastering gas silicate blocks inside a building: technologies used

Gas silicate structures are protected in three stages:

1. Plastering with lime-cement mortar.

2. Priming.

3. Putty.

A lime-cement or lime-gypsum mortar with a thickness of no more than one centimeter is applied to the reinforced surface.

Manual plastering technology is common, if the wall is large and uneven, beacons are installed and the applied layer is equal to a broad rule.

The solution is kneaded in a bucket, small tank or trough, water is poured into the poured mixture and stirred to the required consistency, you need to cook a little, gypsum sets after 20 minutes, cement takes a little more time, so the amount should be sufficient to produce during this time. It can be leveled immediately after covering, the last step is grouting.

After finishing with a long rail, the flatness of the surface is checked, irregularities within 5-7 millimeters will be invisible.

Do I need to plaster the gas block outside

The need to protect the aerated concrete facade is due to its properties:

1. Hygroscopicity will lead to saturation of gas blocks with water, which, in case of frost, will cause the destruction of the structure.
2. Mechanical impact will cause chips, dents, cracks.
3. The material has a porous structure with open pores, through which the circulating air carries away heat.
4. An unfinished aerated concrete house looks unpresentable.

For aerated concrete structures, the danger is the accumulation of moisture inside the blocks, which, when temperature drops, freezes and destroys the block from the inside. Therefore, the protection of external surfaces is mandatory, the method of protection by plastering is widely used for various reasons, one of which is the low cost of this technology.

Materials used for outdoor work

For the application of protective agents outside, substances with the following qualities are required:

• permeable to water vapor;
• not wet;
• with good grip;
• frost resistant.

The main types of mixtures for finishing aerated concrete outside:

• Acrylic for aerated concrete, strengthen loaded structures, plinth.
• Silicate, include liquid glass;
• Silicone based on organic silicon polymers, well suited for facades, but high price;
• Plaster mix;
• Lime-cement composition.

Do-it-yourself internal plaster of the gas block: a feature of the work

Due to the high hygroscopicity of the material, plastering inside the house has its own characteristics.

Plastering surfaces must necessarily provide for the reinforcement process. It is recommended to use a fiberglass mesh that does not degrade in an alkaline environment.

The surface should be painted twice with a deep penetration primer.

Apply a thin layer of plaster about 5 millimeters thick and sink the mesh in it. After drying, apply a base coat using beacons.

Which is the best plaster

If vapor permeability is required for kitchen, bathroom or sauna rooms, mixtures of gypsum with perlite sand are used. Silicate is also suitable, but it must be borne in mind that such mixtures are incompatible with acrylic, silicone, latex materials.

For use on aerated concrete, you can use cement-lime mixtures, which do not require a priming of the walls.

Set of tools

Finishing aerated concrete surfaces requires the following tools:

1. Spatulas.
2. Scraper to remove dirt and debris.
3. Metal brushes.
4. Hammer, for knocking down irregularities, protruding mortar.
5. Sandpaper.
6. Primer brushes, rollers.
7. Master OK.
8. Tank for mixing the solution.
9. Mixer for solution preparation.
10. Falcon, a shield where the mixture is applied.
11. Grout grater.
12. Half-eater.
13. The rule of thumb is to align the corners.

How to plaster: work progress

Ready-made mixtures are great for finishing, but they have a high cost, therefore, for do-it-yourself work, a wall preparation technology is offered, after which you can safely use any composition.

For preparation, you will need tile adhesive, fiberglass mesh, and a deep penetration primer. It is necessary to level all chips and cracks with a compound for laying aerated concrete blocks, then remove dust and debris from the wall with a cheek and paint over with a deep penetration primer twice.

Tile glue is diluted and applied to the surface with a thickness of 5 millimeters, the mesh is pressed on top with a notched trowel. When the layer is completely dry, plaster is applied in the usual way, you can use any solution.

The costs for this technology will be an order of magnitude less than when using ready-made plasters.

How long can you go to the next stages of wall decoration

After the end, the beacons are removed, the dents formed are subsequently sealed with putty.

To proceed to the next types of finishes, you must wait until the walls are completely dry at a constant temperature. Drying will take about a month during the warm season so that temperature changes do not lead to cracking or delamination. It is undesirable to speed up the process; if necessary, a heater is used.

Internal and external finishing of the house is an important stage of construction work, on the quality of which the durability, comfort of living and the aesthetic appearance of the house depend. There are many modern materials and technologies for finishing work, but traditional methods do not lose popularity and are still relevant at the present time. These methods allow you to achieve the required results at low cost and labor intensity.

Useful video

Aerated concrete is a cellular type of concrete, has a porous structure. Therefore, buildings made of aerated concrete blocks easily absorb moisture. Accordingly, for their greater resistance to bad weather, the material requires protection. Among the most common methods is the use of plaster. Let us consider in more detail the features of plastering gas blocks, where to start, what tools will be required, what finishing technologies exist in this way.

Aerated concrete absorbs moisture very well, so you need to protect it

When to start decorating aerated concrete walls

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

Given this, it would seem that the earlier the walls are plastered, the better. But this approach is wrong. Ideally, these activities should be carried out for the next season, when the surfaces are completely dry after laying. Drying time depends on the type of mortar used for laying. For example, a seam made with a concrete-sand mixture will dry longer than the one where the glue mixture was used, since it turns out to be much thicker.

Plastering is recommended for the next season.

Another condition for decorating walls made of aerated concrete, recommended for compliance in order 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 it is not possible to do so, it is necessary at least to cover the stone with a primer, cover it with plastic wrap, so that it will stand without losing its properties until the moment of complete finishing. The most effective water absorption will be reduced by deep penetration primer.

But the opportunity to postpone finishing work is sometimes not available - it is required to carry out them immediately after the completion of the construction of the walls of the building. Here, experts recommend paying particular attention to the composition of the solution. It must have good plasticity, vapor permeability, then moisture can freely come out.

If you need to plaster immediately, then you need to carefully select the material

Which side to start finishing the gas-block building

There are three options for where to start covering aerated concrete wall blocks. Each has its own characteristics, and only one is considered correct. Specifically, you can start:

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

Experienced builders recommend starting plastering outside only when the dwelling is located near water bodies. The primary task here is to protect the 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 may cause cracks, 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 walls from aerated concrete indoors will help to avoid the above problems - this method is considered the most preferable due to its effectiveness. The third method is considered to be the most unpopular way of decorating aerated concrete walls - despite the good vapor permeability properties, “blocking” moisture from both sides, it will have nowhere to go, which sooner or later will lead to delamination of the finishing mixture from the block itself, and later even the destruction of the latter.

Plastering only needs to be done on one side

Sequence of work

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

At the second stage, a special reinforced mesh, resistant to alkaline components, is fixed by means of 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 directly plastering the walls from aerated concrete. Here it is important to choose materials whose vapor permeability properties are higher than those of aerated concrete itself. To increase the service life of the surface, while maintaining its attractive appearance, you can, after a year, by covering it with a water repellent.

The material for plaster should be chosen with a higher vapor permeability than that of aerated concrete

How to plaster - requirements, nuances

Aerated concrete plaster will become of the highest quality, it will not have to be done with a new one in a short time, if the composition of the mixture meets certain requirements, and the packaging contains special markings. Among other things, it must be characterized by:

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

It is especially important to meet these criteria when used outside the building.

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

Silicone plaster is perfect for finishing aerated concrete outside.

Silicone plaster for aerated concrete has the most advantages. 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.

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

In third place is cement-lime plaster. She also has the necessary qualities to cover this type of building.

Aerated concrete plaster can be carried out with a cement-based mixture

Often, gypsum mixture is also used in such houses. 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. This includes the average characteristics of vapor permeability, susceptibility to rapid wetting from precipitation, in addition, stains may appear during its operation.

In addition, acrylic solutions are used for processing. Their rather significant advantage is strength, but one must also remember about the disadvantages - low refractoriness, which is why it is used only in certain rooms, with 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.

Aerated concrete finishing scheme

Used tools

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

Before starting work, you should prepare all the necessary tools

The second, "old-fashioned", method is to use the means at hand: even pieces of wood, pipe cuttings, and other suitable "details". Thanks to the beacons, the plane is perfectly flat, the corners are correct. The listed tools will come in handy if the plastering of aerated concrete walls is done manually.

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

Machine plastering is slightly more expensive

Coating technology

The technology of wall decoration with plaster for aerated concrete is quite simple - it is performed in four steps:

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

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

Having fixed the mesh, the plane is covered with a finishing layer of plaster, and when the coating dries up, the so-called grout is performed, that is, the surface is eliminated from irregularities, roughness, and other minor defects.

Before plastering aerated concrete, level the wall

Features of finishing aerated concrete

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

When plastering gas blocks, a prerequisite is the intended purpose of all funds specifically for cellular material.

Experts recommend not to use cement mixtures for finishing aerated concrete

It is important to start work on the external facing of the facade, when all the "wet" internal work has already been completed, then it is possible to avoid the formation of condensation inside the walls. Moreover, the thickness of the plaster layer inside the building should be twice as large as the outer one, otherwise water vapor will remain inside the blocks, they will dampen. This is the only difference between carrying out these works inside and outside - the technology itself remains unchanged.

If you take into account the recommendations of experts, aerated concrete will serve you for a long time

Thus, we see: with all its advantages, the building material is still quite picky, requires a special attitude. And in order for it to retain its useful properties to the maximum, a number of measures must be taken. But observing the above recommendations, it will prove itself as a very reliable material, it will last a long time, and the home will be cozy and comfortable.

Video: Plastering aerated concrete, preparation of the base

Video: Aerated concrete putty and plaster

Aerated concrete is increasingly used in private construction, competing with traditional bricks. Such houses are much warmer, and less time is required for construction. In terms of technical characteristics, aerated concrete differs markedly from other materials, and these differences must be taken into account when choosing an exterior finish for walls. Plastering is considered the most popular option, and in order for the coating to match the base material as much as possible, you need to choose the right composition.

Let us consider in more detail the types of facade plasters for aerated concrete and the correct technology for their application.

Aerated concrete has a cellular structure with open pores, which provides not only thermal insulation properties, but also high vapor permeability. Thanks to this quality, an optimal microclimate is created inside the house, condensation accumulation is excluded, and the risk of mold development is minimized.

But there is also a downside: open pores increase the hygroscopicity of the material, and the absorbed water destroys the cells when it freezes. For this reason, the exterior finish must necessarily be waterproof in order to reliably protect the walls from moisture, and have a vapor permeability not lower than that of aerated concrete, so as not to impede the escape of vapors.

Important! According to the standards prescribed in SP 50.13330.2012, in heated houses the vapor permeability of materials should increase from the inner to the outer layers. Only under such conditions is the normal functioning of the supporting structures possible. Since for aerated concrete this parameter varies within the range of 0.11-0.23 mg / (m · h · Pa), the plaster composition must be selected with a vapor permeability of at least 0.12 mg / (m · h · Pa).

Additionally, facade plaster should have the following qualities:

• high adhesion to the base material;
• frost resistance (at least 35 cycles);
• increased compressive strength;
• resistance to atmospheric influences;
• decorativeness.

In principle, aerated concrete surfaces can be operated without a protective coating, but after a few years the visual appeal will disappear: the blocks will darken, delamination will appear, and mold may develop. So it is better to immediately complete the facade decoration and then only periodically renew the coating with the help of painting.

Prices for aluminum stairs

Aluminum ladder

Types of plasters for aerated concrete

The most common and most affordable plaster for outdoor use is cement-sand. But since its vapor permeability is only 0.09 mg / (m · h · Pa), it is not at all suitable for aerated concrete structures. Other types of plaster mixes, such as mineral, silicate and silicone, have the required parameters. Let's consider the characteristics of each of them in more detail.

Mineral

Mineral-based plaster is an inexpensive material and is easy to do with your own hands. The main drawback is the limited color gamut, but since this coating lends itself well to staining, this is not such a big problem. The ready mixes contain lime, white cement, marble chips and other fillers, as well as some additives that improve the quality of the plaster. Homemade mixes are most often made from cement, lime paste and sand, or only from sand and lime. It is worth noting that sand-lime mortars have low water resistance, and the direct impact of precipitation is destructive for them.

Silicate

In silicate plaster, liquid potassium glass acts as a binder. Such compositions are more convenient to apply, they are not afraid of moisture and perfectly pass the fumes, which makes it possible to successfully use them for finishing aerated concrete walls as a topcoat.

Silicate plaster - photo

The color gamut is quite limited, but, again, this drawback can be easily eliminated by coloring. Silicate plaster goes on sale in a ready-to-use form, and the cost is slightly higher than dry mineral mixtures.

Silicone

Silicone plaster is based on organic silicon polymers. It has the best characteristics in comparison with other types of plasters: it does not absorb water, it is easy to apply, it is resistant to atmospheric influences, it is vapor permeable and does not lose its visual appeal for a very long time. In addition, such a coating remains elastic and does not crack when the aerated concrete blocks shrink. Silicone plasters are also sold ready-to-use and come in many color options. Thanks to the presence of special fillers, silicone plasters make it possible to create a variety of coating textures. The only drawback is the high price of the material, so not everyone can afford such a finish.

Acrylic

But acrylic plasters for aerated concrete can be used only under the condition of enhanced waterproofing on the inside of the walls and high-quality ventilation of the premises. This is due to the low vapor transmission capacity of the material, which is closer to cement-sand compositions. If you do not provide sufficient protection to the internal surfaces, water vapor will begin to accumulate in the thickness of the walls and provoke the peeling of the finishing layer.

Popular types of plaster mixes for aerated concrete blocks

Name	Specifications
	Dry mix on a mineral basis. Differs in plasticity and ease of application. The ready-made solution must be used within an hour. Application thickness - from 3 to 30 mm. After drying, the coating can withstand temperatures from -50 to + 70 ° C, and at least 100 freezing cycles. Dry mix consumption per m2 is about 14 kg when applied 10 mm thick. You can paint the coating 7 days after application.
	Cement-lime dry mix. Has good resistance to shrinkage, firmly adheres to the base, is not afraid of moisture. It is applied with a thickness of 5 to 30 cm, consumption - 14 kg with a layer thickness of 10 mm. The ready-made solution must be used within 3 hours. Frost resistance of the coating is equal to 50 cycles, can be operated in the temperature range from -50 ° С to + 65 ° С
	Ready mix based on silicone resins. Very flexible, firmly adheres to the base, forms a strong coating with dirt and water repellency. The palette includes about 200 colors and shades. Consumption is 2.5-3.9 kg / m2, depending on the thickness of the application
	Ready-to-use silicone-based plastering compound. It has various grain sizes - from 1.5 to 3 mm, can be tinted in more than 200 colors and shades. The coating is resistant to moisture. Pollution, exposure to ultraviolet radiation and temperature extremes. Consumption is 2.4-4.7 kg / m2
	Ready-to-use silicate plaster. Has a grain size from 1.5 to 3 mm and 200 tinting options. Forms a dense coating with high vapor permeability and moisture resistance. Approximate consumption 2.5-4.2 kg / m2
	Acrylic compound with mineral filler. It can be used for exterior finishing of aerated concrete blocks in the presence of internal water protection and ventilation of the premises. Forms a thin but durable coating that is resistant to negative effects. Possesses frost resistance up to 100 cycles, consumption is 4.5-5.2 kg / m2

Prices for various types of decorative plaster

Decorative plaster

Plastering technology for aerated concrete facades

Conditions for work

It is possible to plaster the aerated concrete facade only after all the "wet" processes inside the room have been completed and the surfaces are completely dry. This applies not only to plastered and painted walls, but also screed on the floor, from which moisture evaporates very actively. The blocks themselves must also be dry - the maximum allowable humidity is 27%. If plastering on wet walls, the intense release of water vapor will cause the coating to flake off.

It is recommended to perform plastering of external walls at a temperature of + 5… + 30 ° C, while the relative humidity of the air should not exceed 80%. If, for some reason, it is not possible to finish the exterior finish before the onset of frost, you need to treat the entire area with a deep penetration primer. The best option is Ceresit ST-17 primer applied in 2 layers. Such protection will be enough until spring, when weather conditions will allow you to start plastering.

Advice. Do not apply plastering compounds in heat, in strong winds and under the influence of direct sunlight on the walls. These factors contribute to the rapid drying of the solution, and it does not have time to firmly adhere to the base. As a result - the appearance of many small cracks and plaster flaking.

Deep penetration primer prices

Deep penetration primer

Surface preparation

As a rule, walls made of aerated concrete blocks are quite even and smooth, therefore, they do not need to be specially aligned. If there are deep chips or dents, you need to seal them with the glue that was used when laying the blocks.

To do this, knead a little glue (you can mix it with the dust formed when sawing blocks), pick it up with a narrow spatula and fill the grooves. Remove excess and allow the solution to dry. In the same way, the empty seams between the blocks are closed. When the glue is dry, the walls need to be rubbed to remove minor flaws. Use a flat metal grater for this. In conclusion, dust is swept away from the entire surface with a brush.

Padding

For priming aerated concrete walls under plaster, deep penetration compounds with strengthening properties are used. They create a very strong elastic film that allows water vapor to pass through, but prevents the material from absorbing water. Additionally, such primers increase the adhesion of the substrate and the finishing layer. Popular media: Knauf Grundiermittel, Siltek E-110, Aerated concrete-contact-1.

The primer is applied in 1-3 layers, depending on the climatic conditions of the area. For example, in dry and warm regions, one layer of primer is enough, and in areas with a damp climate, coastal areas, three layers are needed. To apply the composition, use a roller or a wide paint brush. They are primed with a continuous layer, evenly distributing the composition over the base. In corners and hard-to-reach places, a narrow brush is used so that no dry areas remain.

Plaster and reinforcement

It is not necessary to reinforce a layer of plaster up to 10 mm thick if the walls are properly primed. With a greater thickness, reinforcement is indispensable, and for this, a fiberglass mesh with a mesh size of 3x3 mm is used. The mesh must be alkali-resistant - this will ensure high durability and strength of the finishing layer. This information is indicated on the packaging, so when buying a mesh, pay attention to this point.

Step 1. Prepare a plaster solution. The proportions of water and dry mixture are in the manufacturer's instructions, so carefully read it before starting work. For mixing, take a clean container, pour the specified volume of water with a temperature of + 15 ... + 20 ° C. Pour dry components and stir with a construction mixer at a speed of 400-800 rpm. Let the solution brew for 5-7 minutes and mix again.

Construction mixer price

Construction mixer

Step 2. Take a wide metal spatula, apply a solution to the edge and apply it on the wall in an even strip. The spatula must be held at an angle to the surface and not pressed too hard, so the composition is distributed most evenly. The layer thickness should not exceed 5 mm.

Step 3. A mesh is laid on top of the solution, straightened, and then carefully deepened into the plaster, rubbing with a spatula over the surface with effort. If necessary, add the solution in small portions and rub thoroughly again. After fixing the mesh, apply the solution to the next section and repeat it all over again. The mesh must be laid with an overlap of 40-50 mm to avoid cracks at the border of adjacent areas.

Step 4. In the corners, special perforated profiles are attached with a mesh fixed at the edges. To do this, apply the solution to the very corner, level it with a spatula, apply an angular profile and gently press it. Then, like the mesh, it is deepened into the plaster and the surface is leveled with a spatula. They are placed not only in the outer and inner corners, but also along the perimeter of window and door openings.

Corners and mesh should not protrude above the plane of the wall anywhere. The surface must be flat, smooth, free from visible defects. Now you need to let the solution dry well. Drying time depends on the composition of the mixture and weather conditions, on average it is from 3 to 7 days.

Finishing layer

Mix the finishing layer solution and apply it with a wide spatula to the surface. The thickness of this layer varies between 4-10 mm. Special care is required here, since all defects will remain in plain sight. When plastering adjacent squares, the formation of stripes along the edges should be avoided, all excess must be immediately removed with a spatula.

When the plaster has set enough, but has not yet completely hardened, they begin to grout the walls. For this, it is most convenient to use a polyurethane float, but a metal float is also suitable. The grater must be applied to the surface flat, press down, and smooth the plaster layer in a circular motion. Do not press too hard so as not to leave scratches and dents.

After grouting, you must wait until the plaster is completely dry, and only then proceed to the final stage - painting. You can also apply decorative structural plaster, applying it in a thin layer to the prepared substrate.

Video - Facade plaster for aerated concrete

Plastering walls from aerated concrete inside a residential building is one of the best options to preserve the heat-saving properties of the enclosing structures.

The use of aerated concrete blocks as a building material is almost ideal for low-rise housing. Private houses built from them have such advantages as low weight (and, therefore, do not require the construction of too strong foundations), low thermal conductivity and an affordable price. At the same time, an increase in the humidity of the blocks leads to a deterioration in its heat-saving characteristics and to a heavier structure. To protect the walls, aerated concrete wall plaster is required - sometimes external, but most often internal.

Finishing features

When performing internal plastering of aerated concrete, it is worth considering the features of this material and differences from more traditional brick, concrete and stone. First of all, this concerns the cellular structure of the blocks, which were originally considered a heater, and only then they began to be used for the construction of the walls themselves. Due to the open structure, which is the result of the addition of a special blowing agent (aluminum powder) to its composition, aerated concrete has a high level of vapor permeability. This characteristic is one of the main ones when choosing a material and finishing method.

Regardless of the choice of how to plaster aerated concrete, finishing work should begin from the inside, and only then deal with the facade of the building. Changing the order and performing first external, and only then internal finishing, leads to too high humidity in the room. Escaping (especially in severe frost) steam condenses in the walls at the border of aerated concrete and finishing. The moisture created in this case can lead to cracks in the plaster and the falling off of its pieces. That is why the interior finishing work is performed in the first place.

Choice of method and material

When performing finishing work, plastering of aerated concrete walls is performed in one of two main ways. The meaning of the first is not only to preserve, but even to increase the vapor permeability of the blocks. The second, on the contrary, assumes complete vapor barrier. The advantages of maintaining vapor permeability lie in the creation of an optimal microclimate, and the option with insulating the walls - in the safety of the exterior finish, which is not affected by steam escaping from the building.

Unsuccessful options

It is not recommended to use cement mortar for plastering aerated concrete inside. The first reason is that smooth blocks do not allow the material to stick. The cement layer quickly falls off and the finishing has to be done again. Secondly, the best option for plastering blocks is considered to be a material with the same or greater vapor permeability index compared to aerated concrete. For cement, this characteristic is much lower, which does not allow maintaining normal conditions inside the building. For the same reason, the answer to the question whether it is possible to plaster expanded polystyrene or polystyrene foam will be negative.

In addition, the cement-sand mortar has a high humidity due to the significant amount of water required for its preparation. Aerated concrete structures with a high water absorption rate absorb liquid from the finishing material. The quality of the mortar, which requires uniform drying for curing, decreases, as does its ability to adhere to the walls. As a result, cracks appear on the plaster, and its quality decreases, bringing the next repair closer.

You should not choose a special adhesive mixture for finishing aerated concrete inside. Despite the fact that it is designed taking into account the peculiarities of the material, it is advisable to apply the glue in a thin layer, which is not suitable for protection against cracks. As soon as the vapor permeability of the block is broken, they will immediately appear on the surface of the thin-layer plaster for aerated concrete from the adhesive mixture;

• cracks;
• seam marks;
• and even mold.

Breathable finish

Choosing the option of finishing walls made of aerated concrete indoors while maintaining the natural vapor permeability of the material, they use plaster mixes on gypsum and gypsum putty. Due to the slaked lime and perlite sand in their composition, water vapor easily penetrates through the plaster layer. Another advantage of this option is that there is no need to prime the surface of the enclosing structures.

Slightly less often, mixtures containing a high content of such natural materials with a high degree of vapor permeability are used as internal plaster of aerated concrete walls:

• chalk;
• marble;
• dolomite;
• limestone.

Their vapor permeability indicators are higher in comparison not only with internal, but even with external plaster, and the dried solution is easily rubbed off, acquiring ideal whiteness. The resulting coating has excellent durability and allows further finishing.

You should know: Due to the porous structure of concrete, it is recommended to putty it only after applying a primer. If this is not done, cracks will appear on the putty.

Vapor barrier finish

When choosing the finishing of aerated concrete indoors with the elimination of vapor permeability, that is, with complete insulation of the enclosing structures, one of the materials is polyethylene film. The easiest and fastest way to fix it on the walls is to lay it under one of the finishing layers. However, the speed and ease of installation does not matter if condensation forms on the structures finished in this way and the plaster swells. A more suitable option for plastering aerated concrete inside a house is a sand-cement mixture, which does not contain additives in the form of dolomite flour or lime. With its help, the vapor permeability decreases several times, however, the possibility of plaster peeling increases after a while.

Additionally, to reduce vapor barrier, without too much affecting the quality of the finish, will help:

• oil paint, which covers the walls at the final stage of work;
• applying 3-4 layers of special composition as a primer for aerated concrete;
• using adhesives before applying the plaster. In this case, you can even do without the use of putty. Adhesives have the same properties and, in fact, replace it.

Features of work

To finish the aerated concrete with your own hands, you need to use the same tools that are needed for ordinary plastering. To prepare a plaster mixture, a special container is needed - such as a plastic tank or a bucket made of the same material. They should be large enough to accommodate all the ingredients for the plaster.

Water is added to the dry mixture that is poured into the tank. The mixture is mixed to the desired state with a drill with a nozzle or a construction mixer. As a rule, it is possible to determine the proportions of material and liquid by the inscriptions on packages with building materials.

Plaster of aerated concrete walls is applied inside the room by "throwing" with the help such tools as:

• Master OK;
• plastering bucket;
• trowel.

The surface is rubbed with a trowel. And the excess solution from the wall can be removed with a half-scrubber. It is required to level the wall with the help of beacons, and to pull together the plaster mortar is the rule. Another tool that you cannot do without when performing work is a rail length from floor to ceiling. With its help, defects on the walls are checked - deviations of no more than 6-7 mm are considered permissible.

Plastering process

Having decided the question of how to plaster the walls of aerated concrete, they proceed directly to the performance of the work. They begin, like all surface finishing methods, with the preparation of the base. The blocks are cleaned of mixture residues and the seams between them are closed. Before plastering aerated concrete indoors, a layer is applied to the porous surface.

Solutions for aerated concrete blocks, assuming the preservation of vapor permeability, also
they are able to pass steam, differing not only in high water-repelling properties, but also in the ability to strengthen the enclosing structures. The primer is required to be applied not in one layer, but in several. In this case, it must be taken into account that a new application is carried out only over a completely dried old one.

1. Anchoring the mesh for block reinforcement. Due to the large size of each aerated concrete product, the value of their adhesion to finishing materials is small. And to increase the strength, reinforcement with a material is used, which contains an alkali-resistant fiber. Can be used for a gas block mesh "chain-link" with a small cell size. For its fastening, the use of 120 mm nails is required, which are well driven into aerated concrete;
2. If reinforcement is not used (it is necessary to decide whether a mesh is needed when plastering aerated concrete at the stage of choosing materials), the adhesion of the finishing layers to aerated concrete is ensured by grooves intersecting each other, made by any suitable tools - for example, a hacksaw.
3. Application of the first layer of material (pre-selected, the better to plaster aerated concrete) on the mesh. At the same time, the "spraying" technology is used, which ensures complete filling of the aerated concrete cells, and the leveling of the first layer is not carried out, which improves the adhesion to the next layer of plaster.

When applying the priming solution over the rough aerated concrete plaster, it is required to maintain the layer thickness at the level of 4–5 mm. It is recommended to add slag sand to the primer. When applying the finishing plaster layer, it is advisable to use building material, which contains fine sand, which increases the smoothness of the blocks.

Aerated concrete has long been loved by private developers for its excellent performance characteristics and very attractive cost. However, before starting construction from it, you need to study all the "pitfalls" in this matter in order to build a high-quality and durable structure. So, when planning the finishing, it is important to know how to plaster aerated concrete inside the house, and what materials are prohibited. What are the reasons for such restrictions and what kind of finish is ideal for gas silicate blocks, we will consider below.

Features of finishing aerated concrete walls

Before plunging headlong into the issue of finishing the walls, you first need to understand the structure of the gas blocks, from which the quality of the future home will completely depend.

The main method of obtaining this cellular material is the introduction of special additives into the composition of the concrete solution, which, upon reacting, form air bubbles that tend to escape outward. They simply sprinkle the aerated concrete body not only with voids, but also with thin channels, forming a surface that resembles natural pumice in its texture. Such a structure has excellent positive properties with the correct final processing of blocks:

• high sound absorption coefficient;
• good level of thermal insulation;
• "Breathing" walls create a unique microclimate in the room, keeping warm in winter and cool even in the most intense heat;
• the porous structure of aerated concrete is not susceptible to the emergence and maintenance of colonies of fungal and other microorganisms, which, as a result of their vital activity, destroy the walls.

The porous structure of aerated concrete

But despite these wonderful performance characteristics, aerated concrete also has disadvantages due to its structure:

• the porous structure is subject to increased water absorption, which is fraught with rapid destruction of blocks;
• products with the highest density index, and, accordingly, strength, do not differ in resistance to mechanical stress, leading to spalling and cracking;
• an inhomogeneous structure that retains heat so well is very sensitive to wind. Unprotected bare aerated concrete walls are strongly blown through, and it is cold inside them, even despite a well-organized heating system.

Taking into account all these negative circumstances, we can come to the conclusion that aerated concrete walls need mandatory finishing. But it must be done as competently as possible so as not to disrupt the microcirculation inside the walls, which can lead to destructive processes.

Vapor permeability

The porous structure, which has been talked about so much, has another property - good vapor permeability, which is the key to the durability of any aerated concrete structure.

In the process of life, people release a large amount of all kinds of moisture into the atmosphere. Just imagine how it saturates the air when ironing, washing, drying clothes, cooking or taking a bath. Of course, some of the generated vapors are removed using artificial and natural ventilation, but the bulk falls on the walls. In its pure form without finishing, aerated concrete perfectly passes moisture without retaining it inside its body.

It is another matter if there is a facade and internal cladding, and it is mandatory for such a wall material. Therefore, both finishes should complement each other, maximizing the natural removal of moisture.

For example, a ventilated façade system was chosen as an exterior finish. In this case, the provided ventilation gap does not disturb the natural moisture balance in the aerated concrete wall, leaving complete freedom for vapors to escape. In such circumstances, you can use any plaster for aerated concrete.

Ventilated facade - the best type of exterior decoration for aerated concrete walls

In the case of wall insulation, you need to pay attention to the characteristics of the main material. For example, mineral wool fully complies with the requirements - it insulates with high quality and does not interfere with the removal of moisture. As in the previous example, steam circulation is not disturbed, and the wall remains dry, so you can choose any plaster mixture.

How to maintain a natural moisture balance

But often, for one reason or another, facade decoration is arranged bypassing the basic rules, or, even worse, insulation was carried out with foam sheets (its steam transmission capacity is practically zero) without a ventilation gap. This leads to the accumulation of moisture in the thickness of the wall, which over time manifests itself in damp corners, the collection of condensate in the room - and these are the first harbingers of the appearance of fungal mold.

Consequence of violation of vapor permeability of aerated concrete walls

Such a serious defect can be corrected only by using materials for interior decoration, whose ability to pass vapors is much lower than that of aerated concrete. This shielding method will prevent moisture build-up inside the walls. Best to use:

• paints with a special composition;
• waterproof wallpaper;
• cement-sandy plaster mortars of dense consistency.

But in this case, the importance of a high-quality ventilation device is significantly increased so that the accumulated moisture does not settle on the walls and inside the room, forming a greenhouse effect.

In order not to complicate the construction process, it will be most correct to initially produce interior decoration. After all, the repair involves a large volume of evaporated moisture, which simply needs to go outside, and it is best if he does it through the "bare" gas silicate walls.

And one more little nuance regarding the timing of the processing of walls from aerated concrete blocks. Any cellular materials give good shrinkage, which, in turn, negatively affects any finishing cladding - this usually manifests itself in cracking and peeling of the decorative layer.

Therefore, it is recommended to carry out both internal and facade finishing processes at least six months after the complete construction of the building box and the roof device. It is best to plan this phase of construction during the spring and summer period. As mentioned above - first, the interior decoration is carried out, after the end of all processes, in a month you can start processing the facade.

What plaster to prefer for interior decoration

As noted above, aerated concrete blocks are characterized by a high degree of water absorption, which can lead to excessive drying of the applied plaster layer. This is especially evident on gypsum compositions and cement-based mortars - fast drying, cracking and crumbling. If we go from the opposite direction, and excessively saturate the wall with water, then it will simply be impossible to plaster it, since the applied layer will not be retained on the aerated concrete base.

Choosing the right materials will help solve this problem:

• deep penetration primers with a special composition. Applying them, the main thing is not to overdo it and not to oversaturate the surface of the wall with moisture. Therefore, before use, read the instructions and follow them strictly;
• special mixtures intended for plastering of gas silicate blocks. Their composition perfectly protects such "capricious" porous surfaces. But this is provided that the plaster is diluted in the correct proportions with water. Only following the instructions for use from the manufacturer will help not to make a mistake in this matter.

But that's not all. The cellular surface does not have good adhesion properties. For this reason, it is necessary to initially apply a rough layer of plaster with a thickness of at least 5 mm. But even this finish is prone to cracking and flaking. To prevent this, a plaster mesh is used. Fiberglass or polyurethane is the best choice due to its excellent alkaline resistance and long service life. Only after applying such a reinforced plaster layer and its complete drying, you can safely proceed to finishing.

The best plaster mixes

Having a little understanding of what parameters the finishing mixture should meet, let's consider the most popular and effective types of it:

• plasters based on silicates, namely "liquid glass". They are perfectly combined with aerated concrete surface, especially in terms of vapor permeability. But there is a small "but". Such plaster mixes are incompatible with many types of finishing, for example, based on acrylic, latex, silicone;
• gypsum plasters with perlite sand. They are ideal for aerated concrete wall surfaces, as indicated on the packaging. Any material for finishing is suitable for them;
• cement-lime-based plaster mixes with the addition of optimizing additives. Such compositions were invented specifically for finishing cellular material, even without a preliminary primer. Internal plaster of walls made of aerated concrete of such a plan has not only excellent adhesion properties, but is also applicable for both rough and finishing.

The use of such plaster compositions is ideal for gas silicate walls and, if desired, with their help, you can apply the leveling layer yourself. Like all specialized materials that have been improved for a single application, these mixes have a very high cost, which in the end adds up to a decent amount.

But there is an alternative that will economically resolve the issue of internal plastering - the use of a conventional cement-sand mortar in a ratio of 1: 5. But to use it in relation to aerated concrete surfaces must be extremely careful and not overdo it with the addition of water to the working mixture.

Self-plastering process

Even if you decide that the plastering of walls from aerated concrete inside the room will be done by masters, then it will not hurt to know the process of its implementation. After all, even professionals can sometimes make mistakes, and external control will help to avoid annoying shortcomings.

Preparation for plastering

The algorithm for the process of preparing walls for plastering is quite simple in execution, in which it is impossible to make a mistake. Therefore, you can do it yourself. This will require:

• or plastic 100-120 cm wide;
• adhesive for ceramic tiles;
• deep penetration soil;
• notched trowel with 5-6 mm notches.

Step 1. Carefully inspect the walls for building "jambs". For example, cracks and chips are subject to putty and alignment to the general level of the walls. For these purposes, a regular repair solution is suitable, however, if not much of it is required, then it is best to use glue specially designed for aerated concrete.

Step 2. After the restored parts have dried, brush all walls with a stiff brush to remove dirt and dust.

Step 3. Apply the primer in one coat. This can be done in a way convenient for you, for example, with a roller or brush. To reduce the consumption of the primer solution, experienced builders will use conventional sprayers. If these are not at hand, then you can just as well use an old model of a vacuum cleaner, the principle of which is to blow out air. Only after high-quality drying of the first layer can you start applying the second.

Stage 4. When the primer is completely dry, you can safely dilute the glue according to the instructions and cut the plaster mesh into strips, the length of which should be equal to the height of the walls.

Step 5. Starting from the bottom, throw the prepared glue onto the wall, gradually moving upward. The thickness should be approximately equal to a layer of 5 mm, and the width should be slightly larger than the width of the mesh.

Step 6. Apply a strip of plasterboard and press down until it adheres securely to the wall. Now you can level the adhesive layer with a notched trowel so that the direction of the grooves is horizontal. This improves adhesion to both the wall and future plaster.

Plastering

After the reinforced layer is completely dry, you can safely proceed to the main plastering process.

Stage 1. Wielding a building level, profiles - beacons are exposed.

Stage 2. The working solution is mixed according to the instructions. If the choice fell on a traditional cement-sand composition, then it is taken in a ratio of 1: 5, a plasticizer is added and kneaded to a thick consistency.

Leveling the solution to the beacons

Stage 3. Between the two beacons, a solution is thrown over the entire height of the wall. The rule aligns the resulting layer to the required smoothness level. Once again, attach the rule to the wall and check if there are any gaps between them. If there is, add mortar and level, no - great, plaster all the walls in a similar way.

The described plaster technology is quite simple and even an inexperienced master can use it with success. The main thing is to choose the right way to plaster the walls of aerated concrete inside the house.