The construction of houses from gas silicate blocks is one of the most promising areas in the field of private construction. In particular, aerated concrete blocks have gained great popularity, during the production of which special additives are introduced into the composition of the solution, causing abundant gas formation. As a result, aerated concrete has a pronounced open porous structure, which determines its significant advantages over other materials for masonry walls.

However, such a structure of aerated concrete also brings a number of difficulties in finishing the erected walls. A special approach is needed here, both in terms of the sequence of work and the materials used. In addition, the plastering of aerated concrete walls inside the room will also depend on their planned exterior finish.

What is the "capriciousness" of aerated concrete in matters of finishing, and how these problems can be solved - this publication is devoted to these issues.

Features of aerated concrete

But the materials for the work should go through in more detail.

• The open porous structure of aerated concrete will not allow you to limit yourself to only puttying the walls - a thin layer simply will not hold on to such a surface. Therefore, even if the wall is laid out with the highest precision and does not require special adjustments to its plane, you still cannot do without plaster. And on the aerated concrete wall you will have to “throw” a layer of at least 5 mm.
• Such a layer will be prone to cracking and shedding (the adhesive features of the highly porous structure affect), if it is not reinforced with a reinforcing mesh. If on other wall materials the use of a reinforcing mesh is desirable, then in the case of aerated concrete this condition should be considered as mandatory. The mesh is best - fiberglass, resistant to alkaline environment, so that over time it simply does not dissolve in the thickness of the hardened plaster mass.

The use of reinforcing fiberglass stacks is a prerequisite for high-quality plaster

• Aerated concrete walls are distinguished by high moisture absorption. As experienced painters say, this material literally “drinks” water. It would seem that this is not bad for good adhesion, but it turns out just the opposite. Aerated concrete "sucks" moisture from the applied one, which causes it to dry out quickly, crack and shed - in the case of gypsum compositions, and disrupt the normal hydration of cement, if plasters based on it are used. In both cases, the quality of the coating will be low, and the finish itself will be extremely short-lived.

It is important to find the “moisture balance” correctly, otherwise the work will be of poor quality.

On the other hand, excessive saturation of aerated concrete with water is also fraught with negative consequences. Yes, and such a wall is very difficult - the thrown mortar begins to "creep", the layer becomes loose or inhomogeneous, etc.

Which exit?

- you can use special plaster mixtures specifically for aerated concrete, intended for interior finishing work. Their component composition, when properly mixed with water, in accordance with the instructions, is fully optimized for the characteristics of such a surface and even sometimes does not require preliminary priming of the surface. All this is mandatory indicated by the manufacturer in the instructions for use of the composition.

— application of special primers of deep penetration. Here, however, balance is also important - oversaturation of aerated concrete with impregnating compounds can lead to the opposite effect, since the absorbency of the surface for applying plaster to it is still important.

In both cases, professional masters do not advise immediately to give a thick sketch - it is best to limit yourself to a minimum layer in which a reinforcing fiberglass mesh is embedded. Such a layer does not require a large amount of moisture, it is much easier to “wipe” it into aerated concrete with an effort, and reinforcement will create a solid foundation, without cracks. But after drying such a substrate, it will be possible to safely proceed to the main plastering along the lighthouses.

Video: the work of an aerated concrete wall plastering master

As already mentioned, the composition of the plaster mixture directly depends on whether it is necessary for the wall to leave its high vapor-permeable properties, or, conversely, to make it as difficult as possible for moisture to penetrate the material.

• In the first case, preference is often given to special gypsum-based plaster compositions, which often include light perlite sand. Usually, the instructions for use of the composition indicate that it is combined with aerated concrete (gas silicate) walls. A classic example of such mixtures is Plaster or Osnovit-Gypswell plasters.

Manufacturers claim that the application of such compounds does not even require a reinforcing mesh. But in the case of aerated concrete, this point is better not to be ignored.

• Silicate plasters, based on, are very well suited for aerated concrete, especially in terms of vapor permeability. However, such wall decoration will significantly limit the owners in choosing a finish coating, since silicate mixtures are incompatible with many other organic-based decorative compositions - acrylic, silicone, latex, etc.
• Especially for aerated concrete or similar surfaces, cement-lime-based plasters have been developed. Their composition is optimized specifically for such surfaces that do not even require preliminary priming before plastering. An example is Baumit HandPutz plaster or a mixture from a set of a whole "ensemble" of mortars specially designed for AeroStone aerated concrete.

The composition of such plasters includes cement, building lime, special light aggregates and plasticizing additives, fine-grained purified sand. Such a coating has good vapor permeability, and can be used for both external and internal work on aerated concrete.

• If in the plans of the owners of the house to achieve a minimum vapor permeability of the walls from the inside, then they usually resort to the use of cement-sand plasters without inclusions of lime or dolomite chips (flour). Naturally, the composition usually includes special plasticizing additives that suffocate the adhesion of the coating being created with a porous base.

All specialized mixtures for gas silicate surfaces have one common drawback - they are quite expensive, and with large volumes of work, such internal plastering of walls will result in a fair amount. But this is only a preliminary alignment, without finishing! Is it possible to do it easier, use more affordable mixtures or generally ordinary home-made plaster solutions, for example, based on cement and sand?

It is possible, but only an experienced master can perform such a finish with high quality, to whom his many years of practice allows him to "by eye" determine the condition of the wall, and the need for moisturizing or priming it, and the exact component composition of the plaster. And without the experience of such work, making a mistake on an aerated concrete surface is as easy as shelling pears, and all the work will be done in vain.

However, we can recommend one very interesting way to pre-prepare the gas silicate wall for the future. If everything is done in accordance with the recommendations, it will be possible to apply almost any plaster composition without fear for the appearance of cracks, slipping of the solution, its rapid drying, or, conversely, excessive waterlogging of the wall.

How can I qualitatively prepare an internal aerated concrete wall for plastering

To work, you will need the usual, most inexpensive of all presented in the store, ceramic tile adhesive, fiberglass mesh, deep penetration primer (normal, such as Ceresit CT 17). And then it will be possible to plaster with any composition on a gypsum, cement, cement-lime and other basis. In particular, the usual cement-sand mixture is quite suitable, even in a ratio of 1: 5.

It is rather difficult to determine in advance the amount of plaster mixture to put the wall in order, since it depends on the condition of the surface, its evenness, the presence and depth of level differences both vertically and horizontally. But our calculator will help determine the amount of materials for the preparatory cycle.

It takes into account the conditions for priming the surface in two layers, moreover, with the dilution of the primer with water during the initial application, and the creation of a preparatory reinforced adhesive layer 5 mm thick. Calculations will show the result with the 15% margin "just in case" accepted by builders-finishers.

The calculation is carried out for rectangular surfaces, minus window and door openings.

Currently, such building material as aerated concrete is becoming more and more widespread. For the construction of a low-rise building, it is the best solution. The active use of aerated concrete in modern construction is due to the low cost of blocks, low specific gravity, high thermal insulation properties, the possibility of machining with hand tools, and high fire safety.

However, after the completion of the main construction work, the question of further interior and exterior decoration of the house inevitably arises. There are various types of finishes, but the most common is plaster. Let's try to figure out how to plaster aerated concrete inside the house.

Plaster options for finishing walls made of aerated concrete

In addition to the above advantages, which ensured the popularity of such a building material, it also has disadvantages that require the implementation of a number of additional rules during the finishing work. These disadvantages of aerated concrete include:

• High vapor permeability;
• The ability to absorb moisture very quickly and in large quantities;
• Fragility.

The first two disadvantages have a particularly important effect on aerated concrete plaster. It is the high level of adhesion that significantly complicates the process of finishing both inside the house and outside. There are three options for plastering walls made of aerated concrete:

1. Cement - sand;
2. plaster;
3. Front.

It is important to note that no matter what material you choose for plastering, the finishing of aerated concrete walls should begin with interior work. This is due precisely to the high vapor permeability of aerated concrete. When performing external plastering, the humidity of the room increases significantly, which can adversely affect the quality of internal work.

Wall decoration inside the house can serve two purposes:

1. Maintaining or even increasing the vapor permeability of aerated concrete. This option is used if the main purpose of finishing is to create an optimal microclimate in the house.
2. Complete vapor barrier. This option is used if the outer surface of aerated concrete is also plastered; in this case, the release of steam to the outside is minimized, which has a positive effect on the durability of the external plaster.

Now consider what material will be most suitable for plastering your particular home.

Cement - sand plaster. Often, many people ask themselves: is it possible to plaster aerated concrete with cement mortar? Wall decoration with such material is highly undesirable for the following reasons:

1. The vapor permeability index of cement is significantly lower than that of aerated concrete. It is possible to ensure an optimal microclimate in an aerated concrete house only if the vapor permeability of the finishing material is equal to or exceeds that of aerated concrete.
2. With significant moisture absorption rates, aerated concrete will intensively absorb moisture from the sand-cement mortar, and this will significantly reduce the quality of the plaster, since the acquisition of optimal strength parameters by cement plaster is possible only if it dries slowly and evenly.
3. Low adhesion and high specific gravity of the solution exclude the possibility of its reliable adhesion to the material.

Gypsum. Plastering aerated concrete inside the house with gypsum has both advantages and some disadvantages. The benefits include:

1. 1. Fast drying;
2. 2. No shrinkage;
3. 3. Ability to obtain a smooth surface;
4. 4. With skillful plastering of aerated concrete walls, you can avoid applying the finishing layer. It is unlikely that the quality of the surface will allow tinting, but wallpapering is quite acceptable.

The disadvantages of gypsum mixtures include:

1. Low vapor permeability;
2. A fairly large volume of water is needed to knead the mixture;
3. High adhesion of dried plaster to precipitation and moisture in general.

Despite these shortcomings, plastering aerated concrete with gypsum is quite acceptable.

Front. This type of plaster mixture is optimal for plastering aerated concrete indoors and outdoors. The vapor permeability indicators of such a composition correspond to those of aerated concrete blocks, they are characterized by high adhesion, and they also have good aesthetic properties after drying.

Interior decoration of the house from aerated concrete

Currently, there are a large number of ready-made dry mixes for wall plastering. When choosing a material for plastering work, the following factors should be considered:

1. The plaster mixture must have good vapor permeability parameters, at least equal to the parameters of aerated concrete;
2. An excessive amount of water must not be used to prepare the working mixture.
3. The selected mixture must have a high coefficient of adhesion to the base;
4. The plasticity of the plaster should provide the walls with resistance to cracking;
5. The frost resistance of the selected mixture must correspond to climatic conditions;
6. The time until the start of setting of the newly prepared mixture, in other words, the time during which the prepared mixture has sufficient plasticity to be applied to the base.

Currently, Ceresit CT 24 is confidently leading in the market of dry mixes for plastering aerated concrete, with a huge variety of choices, in terms of price-quality ratio.

In conclusion, I would like to remind you that regardless of how to plaster aerated concrete, compliance with the technological regimes indicated by the performer of the plaster mix is ​​directly related to the quality and durability of the work being done. Do not neglect the preparation of the base. Preliminary removal of various masonry irregularities will allow you to significantly reduce the layer of applied plaster on aerated concrete, and, consequently, its consumption.

Aerated concrete blocks are increasingly being used in the field of low-rise construction. That is why the question of how the internal plastering of aerated concrete walls is done is becoming more and more popular.

In this article, we will consider the features of the use of various plaster mixtures in the finishing of low-rise buildings, mainly for residential purposes.

The need for timely wall decoration

Before deciding on the better to plaster aerated concrete walls, let's figure out what this material is and what are its characteristics that can affect the finishing work.

Aerated concrete has a low specific gravity, which minimizes the degree of mechanical load on the foundation. The light weight of the building material is explained by the cellular structure of the blocks. And, if low weight is an advantage, then the cellular structure turns into a disadvantage.

The fact is that aerated concrete blocks are characterized by low hydrophobicity. They literally absorb moisture, both from the external environment and from inside the building. Absorbing moisture, the blocks lose their original heat-saving qualities. In addition, excessive moisture leads to the gradual destruction of building materials and structures built with its use.

It is for this reason that plastering of aerated concrete walls should be carried out in a timely manner.

Related articles:

Features of wet plastering of walls made of aerated concrete blocks

Plastering of building objects erected with the use of cellular concrete is mandatory both from the outside and from the inside. The finishing process should begin from the inside and then proceed to the facade cladding.

A gross mistake is the external plastering of aerated concrete walls, carried out in the warm season. In this case, interior decoration begins with the onset of cold weather. Meanwhile, the water used in the manufacture of wet plastering mortars will, for the most part, permeate to the outside both through ventilation and through blocks of cellular concrete.

Eventually, water vapor will condense inside the blocks at their dividing line with the exterior finish, as the walls will eventually be plastered on both sides. With a significant decrease in ambient temperatures, the external plaster, due to the freezing of moisture in the walls, will crack and peel off.

The technology of plastering walls made of aerated concrete does not provide for the use of cement-sand mortars, since such a coating will eventually become a serious obstacle to vapor permeability. As already mentioned, excess moisture in the walls must find a way out, otherwise the external plaster will deform over time and come into disrepair.

There are two ways to solve the problem of removing excess humidity without compromising the microclimate inside the room:

• Through the use of plaster mixtures specially designed and manufactured for finishing foam concrete structures.

Speaking of special mixtures that do not interfere with the removal of steam, we mean plaster mixtures with a high content of gypsum.

Today, in any hardware store you can buy a wide range of gypsum putties, both for outdoor and indoor use. The composition of high-quality modern putties, in addition to gypsum, includes slaked lime and fine-grained perlite sand. Due to such components, the mixtures are characterized by a high degree of adhesion, and therefore it is not necessary to prime the surface of the walls before finishing work.

The finished plaster layer of putty acts as a filter material, due to which water vapor is effectively removed to the outside, while moisture from the outside practically does not enter the walls.

• Using a vapor barrier film installed from the inside of the room.

Vapor barrier material - penofol

The film laid on the wall, before applying wet plaster, prevents the penetration of moisture into the blocks, so the type of exterior finish is not fundamentally important.

At first, the plastering of the walls inside the room was carried out using ordinary polyethylene film. As it turned out, the use of such a vapor barrier is not the best solution, since there is a high probability of condensation and swelling of the plaster. The solution to the problem is the use of polyethylene non-woven fabrics with microperforations.

When using a moisture barrier, it is allowed to use cement-sand plaster mixtures made without the use of dolomite flour or lime as fillers.

The choice of tools for finishing work

Before plastering aerated concrete walls, you need to decide on the choice of tools.

In principle, the tools required are the same as for conventional plastering:

• a plastic container for stirring the solution with a volume of at least 10 liters;
• perforator with adjustable speed and a special nozzle for mixing;
• plaster rule;
• spatulas of different widths (wide 50 cm and narrow 10-15 cm);
• medium-sized trowel or plaster ladle;
• water level;
• graters for leveling and grinding.

The technology of applying gypsum putty

The modern technology for plastering aerated concrete walls inside and out using gypsum putties is as follows:

• We prepare the surface. To do this, carefully clean the walls from dirt and dust.

To increase the adhesion of the putty and the surface, we use an acrylic primer, which can be applied with a wide brush or roller. At the same stage, we install beacons. Of course, you can work without beacons, but with special guides, the finish will be faster and better.

If the wall does not have significant irregularities, we choose the thinnest beacons to reduce the consumption of putty. The installation of beacons is carried out on a thick gypsum or alabaster mortar.

• We prepare a solution. In accordance with the manufacturer's instructions, pour water into a previously prepared container and pour dry gypsum mixture.

Tip: It is advisable to knead no more than 10 liters of solution at a time, since this amount is on average enough for 1 hour of work.
If you knead a larger amount of the solution, it is likely that it will seize before it is completely used.

You can find a detailed description of the technology of mixing gypsum putty in the relevant articles on our portal.

• We apply the first layer of putty. Plastering on the lighthouses, we apply the solution from the bottom up to about the bottom of one third of the wall. You can throw the solution into the gap between adjacent lighthouses on a pre-moistened wall with a trowel, or you can apply it with a spatula. The outline layer should be 1-2 cm above the level of the surface of the beacons.

• Align the applied solution. To do this, we apply a plaster rule to the surface of neighboring beacons and lead it up, periodically shifting the tool from one side to the other. In the process of leveling, putty accumulates on the rule, which must be removed in a timely manner with a spatula and mixed with the bulk of the solution.
• After the first layer of plaster dries, you can proceed to the final leveling. A new putty mortar is diluted, which is applied and smoothed with a wide spatula.
• The final stage of plastering is grinding the finished surface and applying a primer layer. After that, the wall covering is completely ready for painting work or applying decorative plaster.

Features of the use of cement-sand mortar

As already mentioned, before plastering aerated concrete walls with cement-sand mortar from the inside of the room, it is necessary to take care of an effective vapor barrier.

Therefore, the work instructions are as follows:

• The surface of the wall is cleaned of contaminants, after which a film vapor barrier is applied to it. We fasten the vapor barrier film in layers overlapping each other.

• We fill the plaster mesh. In this case, it is optimal to use a metal mesh netting with a cell side of no more than 3 cm. Of course, you can use a plastic mesh, but the metal netting has a relief, which allows the mortar to better adhere to the wall surface.
  We fasten the grid strips vertically with a gap between the previous and subsequent strip for the width of the beacon.
• We install beacons in the gap between the grid stripes. We select beacons so that they are about 5 mm thicker than the mesh.
• We prepare the plaster mortar in the proportion of 1 part of cement to 3 parts of sand. We mix all the components in a dry form until a homogeneous mass is formed.
  After that, add water in small portions to the dry mixture and mix until the solution reaches the desired consistency.
  The readiness of the solution is determined as follows: we collect the solution on the trowel, tilt the trowel and watch how the solution slides down. The solution, ready to use, slowly slides, and does not drain or fall down in clods.

• Sketching and leveling, in this case, is performed exactly the same as in the previously described method.
• After the sketch and leveling of the solution is completed, the dried surface is rubbed with a foam float. Grouting is carried out in a circular motion with periodic spraying of the surface with water from a spray bottle.
  After the grout is completed, you can start applying decorative plaster.

Dry plaster technology

Finishing the walls of aerated concrete blocks with your own hands, you should not forget about dry plaster. Wall decoration with GVL, OSB and other materials in the form of plates is becoming increasingly popular everywhere.

Of course, this type of finish will be an excellent solution for interior work, while the outer side of the walls can be plastered in the usual wet way.

Consider the technique of frame wall cladding with plasterboard sheets, especially since the price of such a solution is affordable for most people.

Important: the average cost of a running meter of a frame profile is 30 rubles, while 1 sq.m. drywall will cost from 100 rubles.

Finishing work is carried out as follows:

• We equip the walls with vapor barrier. For these purposes, we use glassine, membrane or polyethylene non-woven materials with microperforation. We fix the vapor barrier with vertical strips with an overlap of 10-215 cm on each other.
• We mount the crate from a metal profile. Until recently, the crate was made exclusively with the use of wooden beams. But wood is a short-lived and expensive material. Therefore, metal galvanized profiles, which are light, inexpensive and stainless, have replaced wooden products.

To finish the walls inside the room, you will need a guide, rack and corner profile.

We fix the rack profile at a distance of 60 cm from each other, while the guide profile can be installed in increments of 1 meter. We fasten the profile with special dowels for working with foam concrete.

Important: To prevent the appearance of the drum effect, mineral wool slabs should be laid between the gypsum board and the vapor barrier.

• We fix drywall plates with self-tapping screws, but not closer than 15 mm to the edge of the sheet.
• We install the drywall of the upper row with some offset relative to the lower row.
• After the wall decoration is over, you can start puttying the joints between adjacent drywall slabs. We do this with the help of a special mesh tape, which we glue to the joints with a putty mixture.

Conclusion

Now you have a general idea of ​​​​what is the instruction for finishing walls from aerated concrete blocks. Despite the fact that there is a common opinion about the fragility and fragility of this material, aerated concrete blocks are not much inferior to other building materials.

However, this is possible only if the walls of the foam blocks are protected in a timely manner with high-quality plaster from the negative impact of environmental factors. Again, despite the fact that the plastering of such walls is considered problematic, the correct approach to business, in accordance with the above recommendations, will ensure the proper quality of the finished result.

You can find more useful and informative information by watching the video in this article.

Plastering walls made of aerated concrete is a justified measure. , like the foam block, despite all its advantages, the material is hygroscopic. This means that it easily absorbs moisture. Therefore, a gas-block house must be protected from the weather. If the gas block gets wet in the rain and then dries, it will not lose its properties. And if it gets wet in winter, then the water accumulated in the pores of aerated concrete will freeze and expand. This is fraught with the appearance of small cracks that spoil the view, as well as the occurrence of more serious damage.

Conclusion: protection of aerated concrete from the outside from freezing, moisture, snow and other precipitation is a necessary measure. During and during winter conservation (if necessary), this function can be performed by a film stretched over the walls. During the operation of the house, it can be any facing material for the exterior of the facade - plaster for cellular concrete. The main thing is to create vapor permeability conditions so that the aerated concrete "breathes".

The exterior finish of aerated concrete houses, in addition to block protection, allows:

• strengthen the heat and sound insulation of the walls;
• eliminate the likelihood of wetting the walls;
• protect the house from sudden changes in temperature;
• decorate the facade of the house (decorative plaster for aerated concrete).

One of the most popular ways to exterior finish an aerated concrete house is to apply plaster. Therefore, questions often arise, for example, how and with what to plaster aerated concrete, which we will try to answer as fully as possible. We will conduct a comparative review of the characteristics of the best mixtures for facade decoration, and also describe the wall plastering technology in the form of step-by-step instructions understandable to beginners without construction experience.

Plaster for aerated concrete

Summarizing the experience of builders and owners of aerated concrete houses, we can conclude that three types of finishing materials are used for plastering aerated concrete walls:

Cement-sand plaster for aerated concrete

Is it possible to plaster aerated concrete with cement mortar?

No. Regardless of whether the gas blocks were laid on cement or on glue. In general, it is highly undesirable to plaster aerated concrete with cement mortar, because aerated concrete is very smooth and the mortar does not adhere to it, and it also strongly absorbs water from the mortar.

Reasons why it is impossible to plaster an aerated concrete house with cement mortar:

• The cement mortar has a lower vapor permeability than the gas block. This is the most important reason why you shouldn't use it. In the case of finishing walls made of aerated concrete, professionals have a rule that only that finishing material can be used, which, in terms of vapor permeability, does not differ from the aerated concrete itself or has a higher indicator compared to it. Only in this case, the optimal microclimate of the aerated concrete house will be maintained.

Note. For the same reason, it is undesirable to use rigid heaters (polystyrene and expanded polystyrene) for insulating a house made of aerated concrete.

• Cement-sand mortar has a high moisture content. To knead the components in the sand-cement mixture, you need to add water. It is also obvious that aerated concrete, having a significant rate of moisture absorption, will tend to absorb this water from the solution. This, in turn, reduces the quality of the applied mortar and its ability to adhere to the wall. After all, concrete gains strength only if it dries evenly and slowly.

Remember, the foundation must be periodically moistened and covered with a film to ensure uniform drying. So why should it behave differently on the wall? The primer saves the situation, but not much. The appearance of a cobweb of small cracks on the plastered surface of aerated concrete cannot be avoided.

Note. In order to save money, you can mix a cement-sand mixture and a special mixture for finishing aerated concrete blocks in a ratio of 1 to 1. But is such savings needed, which will significantly reduce the speed of work, and the finished surface will not be 100% of high quality.

• Cement mortar for plaster has low adhesion. It cannot provide high-quality adhesion to aerated concrete. One of the reasons can be considered the weight of the solution and the presence of large impurities in its composition.

You can increase the adhesion index (sticking, adhesion of surfaces) by adding lime to the classic cement mortar recipe (proportion: 8-10 kg of lime per 100 kg of concrete).

Cement-lime plaster can be purchased as a ready-made dry mix. For example, dry building cement-lime mixture CREPS Extra-light (240 rubles / 25 kg), Startvell T-21 (208 rubles / 25 kg), Baumit HandPutz 0.6 (300 rubles / 25 kg).

• obligatory application of the final layer. Because it is difficult to make a smooth surface using a sand-cement mixture.

Is it possible to plaster aerated concrete with aerated concrete glue?

Also undesirable. Although designed with the specifics of aerated concrete in mind, it is intended for thin layer application and jointing, not for exterior wall applications.

Violation of the vapor permeability of aerated concrete will lead to such problems as cracking of the finishing layer, the appearance of traces of seams (disappear after drying), the appearance of mold.

Gypsum plaster for aerated concrete

Advantages of plaster based on gypsum:

• high drying rate;

• non-shrinkage of the solution;

• the ability to make a smooth surface;

• no need for a top coat.

Disadvantages of gypsum plaster:

• mediocre vapor permeability;

• greater, in comparison with a special mixture, the water content required for mixing the mixture (10-15 liters per bag);

• getting wet quickly during rain or snow;

• the likelihood of spots on the surface that have to be painted over.

Despite the disadvantages, plastering the walls with gypsum is an acceptable option for finishing aerated concrete. Well proven: gypsum vapor-permeable highly plastic plaster mixture Pobedit Velvet G-567 (previously Pobedit-Egida TM-35 for 320 rubles / 25 kg.), Knauf Rotband (360 rubles / 30 kg) and Bonolit (290 rubles / 30 kg).

Facade plaster for aerated concrete

The most effective material for plastering exterior and interior walls of aerated concrete. Facade plaster has a number of characteristics, including the vapor permeability index identical to that of aerated concrete (for most types of plasters), good adhesion to the base, beautiful appearance.

When choosing how to plaster aerated concrete, it is best to focus on a high-quality special mixture. In addition, the use of facade plaster simplifies the finishing of an aerated concrete house with your own hands.

What kind of plaster is better to plaster aerated concrete walls?

There are a variety of ready-made mixtures for plastering aerated concrete walls on the market. To make the right choice, you should pay attention to the characteristics of the plaster:

• vapor permeability;

• the required amount of water for mixing the mixture (no more than 0.2 liters per 1 kg of the mixture);

• boundary values ​​​​of the thickness of the plaster (minimum and maximum);

• adhesion to the base (minimum 0.5 MPa);

• resistance to low temperatures;

• crack resistance;

• solution pot life. The more, the easier it is for beginners to work with it.

And only when choosing between two equivalent mixtures, one should be guided by the price, it decides not the last role in this matter, but not the key one either.

According to reviews, plastering of aerated concrete walls outside the premises is popular among users - a dry mix with plasticizers Ceresit CT 24 (380 rubles / 25 kg), leading in terms of price / quality.

The material was prepared for the site www.site

When can aerated concrete walls be plastered?

Since aerated concrete easily absorbs moisture, it is better to protect it from getting wet immediately. We repeat, it is not critical if the material gets wet, but you should not allow moisture to freeze in the gas block. This can lead to its weakening and the appearance of unwanted cracks.

Haste in facing is also useless. After laying aerated concrete, the walls should dry well. That is why the plastering of aerated concrete walls is carried out only in the warm season. In the case of using a concrete-sand mortar as a binding element when laying aerated concrete blocks, the drying time increases, since such a seam is several times thicker than a seam made with a special adhesive mixture.

If it is not possible to finish the house during the warm season, you need to cover the walls with any deep penetration primer. For example, Ceresit ST-17 (549 rubles / 10 l).

The primer will reduce water absorption. It is also desirable to cover the walls with polyethylene left over from packing pallets with aerated concrete.

According to the masters, the most preferable time for finishing work is the period when the night temperature exceeds 0 °C. For central Russia, this time is from late March to early October.

From which side should you start finishing the house from aerated concrete?

We will conduct a comparative analysis of several popular options for the order of execution of wall decoration.

Option 1
First, the exterior of the house is made of aerated concrete

There is an opinion that the most important thing is to protect the gas block from the street, because. it absorbs moisture. However, this is not so, even after standing without protection (but primed) for a whole winter, the gas block will “give up” the accumulated moisture in the spring. And if it is closed from the outside, where will the vapors be directed? That's right, indoors. This will not only increase the drying process and delay the interior decoration, but is also fraught with the appearance of cracks inside the room.

Option 2
First, the interior decoration of the house is made of aerated concrete

With this approach, the pores of the aerated concrete block are partially closed in the process of finishing work. And if they are plastered first from the outside, the accumulated water vapor will simply have nowhere to go. Settling inside the block, moisture will contribute to its destruction. Plastering the walls of aerated concrete indoors will avoid this situation.

After the plaster has touched the interior walls and dried well, you can start finishing the exterior walls.

Option 3
Simultaneous finishing inside and outside the house

The method is the least preferred. The moisture that the gas block “pulls” at the same time from the outside and from the inside will not have the opportunity for a quick exit at all.

Despite the fact that plaster for aerated concrete has good vapor permeability, the speed of this process is not so high. Which is especially critical in the cold season (at night temperatures below zero). In this case, water vapor will settle in the form of condensate and, as a result, can lead to peeling of the plaster layer from the aerated concrete. In practice, this option will lead to the destruction of the gas block as quickly as possible.

Theoretically, each of the options has the right to be implemented. But the second one is correct.

How to plaster aerated concrete walls with your own hands

We figured out the question of whether it is possible to plaster aerated concrete. Now it is important to understand how to do it correctly, without prejudice to aerated concrete to let in moisture.

Plastering of aerated concrete blocks has no fundamental difference from the performance of works of this kind on other materials. The putty application technology differs only in a few details, which will be emphasized.

Internal plaster walls made of aerated concrete

The technology of finishing aerated concrete with plaster indoors - the sequence of work:

1. Foundation preparation

It begins with the alignment of the walls - the removal of irregularities is done using a planer or grater for aerated concrete. This work is recommended to be done at the stage of building a house, but many people neglect this, saving time. In principle, this stage can be omitted, which will lead to a significant increase in the consumption of the mixture and an increase in the thickness of the coating layer. In turn, this is fraught with flaking of the plaster and cracks.

2. Applying a primer

Often there are recommendations that the primer should be diluted with water 1 to 1. This is fundamentally wrong, because. reduces its ability to increase surface adhesion. There are better ways to save money. For example, remove dust from the surface by applying clean water to it. Water is applied with a brush or roller as if it were a primer. And then, after drying, a primer is applied.

The choice of primer depends on the purpose of the room to be finished. For a corridor or hallway, any universal primer is suitable, for example, Unis (250 rubles / 5l). For the bathroom and kitchen, it is advisable to use a deep penetration primer, for example, Prospectors (450 rubles / 10 l).

3. Installation of beacons

Beacons, as the name implies, determine the thickness of the application of the solution. They are set to the width of the rule. The accuracy of the installation is determined by the building level.

4. Throwing a "fur coat"

This is the name of the method of applying the first layer of plaster. The work is done from the bottom up. Next, you need to base the rule on the beacons and align (extend) the sketched layer along them. If voids appear, they must be repaired immediately. The main thing is that the plaster does not peel off from the base. If this happens, you need to remove the plaster, treat the surface with a primer and apply the solution again.

5. Processing the first layer

After the first layer of plaster has dried, it must be slightly moistened (with a spray gun) and leveled. Since the beacons serve as cold bridges, it is advisable to remove them at this stage, and seal the places (recesses after dismantling) with mortar.

6. Forming corners

A perforated corner with a mesh is used to arrange and reinforce the outer corners.

7. Finishing

Grouting (if necessary) and painting of aerated concrete walls is carried out. In the case of wallpapering, finishing is not required.

For paint for aerated concrete, requirements are also put forward regarding vapor permeability. Such properties are possessed by interior paints based on PVA, latex, acrylic emulsions, on organic solvents and cement paints.

An example is ESKARO AKZENT (antibacterial paint, 325 rubles / 0.9 kg). At the same time, for rooms with high humidity, special paints should be used, for example, AquaNova Premium (282 rubles / 2.8 kg)

How to plaster aerated concrete walls - video

External plastering of aerated concrete walls

Decorative plastering of the facade of the house may involve the application of plaster for outdoor use in a thick layer (thick-layer finish) or several layers (thin-layer plaster).

Consider a multilayer version of applying thin-layer facade plaster for aerated concrete. Its feature is the creation of three thin (no more than 10 mm) layers.

Technology for applying plaster outside:

• wall preparation. Includes leveling the surface to reduce the consumption of the mixture and the thickness of its application;

• surface priming;

• applying a thin layer of plaster mixture (up to 5 mm). Its purpose is to serve as a basis for attaching the grid;

• reinforcement of plaster with mesh;

How to properly reinforce plaster

A metal mesh with small cells can be used as a reinforcing layer, for example, a steel mesh with a wire diameter of 0.1 mm and a cell pitch of 0.16x0.16 mm (average price 950 rubles / sq.m. = 2,850 rubles / roll) or fiberglass mesh (for example, reinforcing fiberglass mesh with a cell pitch of 50x50 mm (approximate price 17.60 rubles / sq.m = 880 rubles / roll).

The mesh is attached with an overlap of 50 mm. At the same stage, the corners of the building are formed using a perforated corner with a grid. The mesh helps prevent cracks in the plaster due to shrinkage of the building. Thus, the plaster of the aerated concrete facade will not be covered with a web of small cracks. The mesh is sunk into the applied solution with a spatula. It is especially important to install the grid in places of high voltage, near windows and doors.

Advice. Mounting the mesh on a dry wall will not give any result, because the mesh will be fixed to the base with self-tapping screws. In the case of its installation on the solution, it forms a monolith with the solution, and will move with it.

• alignment of the plaster layer on the grid;

Next, you need to wait until the first layer dries completely. Otherwise, it may fall off under the weight of the second layer. Since this method involves a thin-layer application of the solution, it will take 3-4 days to wait. The thicker the layer, the more. You can check if the layer is dry with water. If you spray on the wall and the water is absorbed, then it's time to get to work.

Note. When the plaster dries, it must be protected from the influence of environmental factors (moisture, snow, rain).

• applying a second layer of plaster. This layer is considered leveling, therefore, increased attention is paid to the evenness of application and the formation of a smooth surface;

• applying the third (finish) layer of the plaster mixture, followed by grouting if necessary;

• painting a plastered aerated concrete wall or applying a textured plaster mixture, for example, Pobedit-Bark beetle (340 rubles / 25 kg).

  For painting aerated concrete, only paints for outdoor use are used. For example, Nova-Facade (590 rubles / 7 kg), Gasbetonbeschichtung from Dufa (2674 rubles / 25 kg), ROLPLAST Gordianus (3700 rubles / 10 kg), Dyotex (concentrate, 5500 rubles / 15 kg).

• application of a hydrophobic agent. This is a special solution that professionals recommend applying a year after staining, after all facing work is completed. The water repellent will give any surface additional water-repellent properties. A special water repellent agent for aerated concrete "Neogard" (350 rubles / 1 l) has proven itself well.

Aerated concrete putty

When deciding how to putty aerated concrete, you need to know that there are three types of finishing materials on the market that are similar in purpose, but differ in their composition. All this, facade plaster for aerated concrete, sold as a ready-made mixture. It is intended for thin-layer finishing of the plastered surface.

Ready-made silicate plaster, for example, Baumit SilikatTop Kratz Repro 3.0 mm (3700 rubles / 25 kg)

Silicone plaster, for example, Baumit SilikonTop (3300 rubles / 25 kg) Acrylic plaster, for example, Ceresit CT 77 (3800 rubles / 25 kg) Facade "fur coat" Weber.pas akrylat or Weber.pas akrylat Fur coat 615С 1.5mm (1800 rub/25 kg)

Conclusion

Consistently performing work on plastering walls made of aerated concrete and using only vapor-permeable materials, it is possible to provide a reliable finish that will decorate the facade of the house for more than one year. And scheduled repairs will be reduced to periodic painting, to restore the color of the paint and eliminate small cracks.

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Primer for aerated concrete: requirements, examination of samples, application and subsequent finishing

Aerated concrete is one of the most popular building materials in private construction. However, it has a number of features that must be taken into account when decorating the walls externally and internally. Today we have to get acquainted with primers for aerated concrete - their features, application and methods of finishing after priming.

Properties of aerated concrete

Advantages

Thanks to the technology of its production, this material has a number of properties that are extremely useful in construction:

• Ideal geometry that allows you to make the seams between the blocks as thin as possible;

Each seam is a cold bridge and contributes to an increase in heat loss. The thinner it is, the less heat leakage. That is why when building walls, not a cement-sand masonry mortar is used, but a special glue with a finely dispersed filler.

• Low specific gravity (from 300 to 1200 kg/m3);

In most cases, aerated concrete with a density of 400-700 kg/m3 is used as a building material. A material of lower density (300 kg/m2) is used as a filling of the walls of frame-monolithic buildings, a higher one (the so-called structural aerated concrete) is used for the construction of load-bearing structures.

• Low thermal conductivity, which is provided by the porous structure of the material;
• High vapor permeability. It is due to the fact that a significant part of the cells in the structure of aerated concrete are open. Vapor permeability allows you to maintain a comfortable microclimate inside the house, getting rid of excess moisture.

Flaws

As is customary, the shortcomings of the material are a continuation of its advantages:

• Aerated concrete has a huge, by the standards of building materials, water absorption - up to 30-35% of its own weight;

• When moisture is absorbed, the heat-insulating properties of the walls fall sharply: the water that fills the cells is much more thermally conductive than air;
• Freezing of water inside the cells leads to the destruction of the walls at an accelerated pace. Remember: during the transition to a solid state of aggregation, water increases in volume; during crystallization, it breaks the cells, giving rise to cracks inside the blocks;
• Not only that: consistently high humidity leads to the appearance of a fungus, which, feeding on minerals, additionally accelerates the destruction of walls.

Where can water get into the thickness of the walls?

There are actually only two sources:

1. Precipitation. With oblique rain, insufficiently wide roof overhangs leave the facade without protection from moisture;

1. Condensation of water vapor filtered from the interior. It becomes possible with an incorrectly chosen finish structure.

About vapor permeability

So what should be the structure of the outer wall in order to completely exclude water condensation inside the aerated concrete blocks?

One of the main building rules says: the vapor permeability of enclosing structures should increase from the inside to the outside. Interior decoration should pass less water vapor than the material of the main wall; external - the same or more.

What happens if you break this rule?

It is obvious! The interior finish will allow a sufficiently large amount of moisture to pass through, which will linger in the thickness of the wall. We have already studied the further development of the scenario: an increase in thermal conductivity and crystallization of water in the pores during the very first frosts with the accompanying destruction of the wall material.

conclusions

• External wall decoration should be carried out with materials with the highest possible vapor permeability.. The primer for aerated concrete blocks is no exception: it should not create a barrier to water vapor;

At the same time, it is highly desirable that the soil has water-repellent properties, making the open cells of aerated concrete closed. In this case, the moisture absorption of the walls during precipitation will decrease, and at the same time the paint consumption during fine finishing.

• For interior work, a normal deep penetration primer or an adhesive primer with quartz sand can be used. The latter, as the name implies, will significantly improve the adhesion of walls to plaster or putty.

Priming purposes

Is it necessary to prime aerated concrete walls for plastering or painting?

So to speak: highly desirable. On the one hand, the oldest residential building made of this material in the post-Soviet space was built in 1939 and has been standing for almost 80 years without external finishing in general and without applying water-repellent compositions to the facade in particular.

On the other hand… let me just list the results of applying the primer:

• Improves adhesion between wall blocks and the next layer of finish (plaster or decorative putty);
• The surface is strengthened: the primer binds the outer layers of the wall, increasing their tensile and bending strength;
• Reduced paint consumption when plastering, the walls absorb less cement milk, which means that the plaster retains greater strength;
• Moisture of the walls and all the negative consequences associated with it are excluded.

Sample study

And now let's take a closer look at several products from the market sector of interest to us.

For outdoor decoration

So, how to prime aerated concrete before plastering the facade?

Eskaro Aquastop Facade

Polyplast PGS-116

Polimin Super-primer AC-5

For interior decoration

Knauf Betokontakt

Application

How to prime aerated concrete walls with your own hands?

By the time work begins, the wall must be cleaned of dust, dirt and streaks of masonry mortar or glue. If there are oil stains on it, aerated concrete is degreased with any organic solvent. .

The primer is carried out at an air and base temperature not lower than + 5C, otherwise the water base of the soil will freeze. Adhesive primers are applied either with a wide brush in one layer.

When priming, tinted primers (for example, pink Betokontakt from Knauf) are very convenient: they allow you to visually control the condition of the surface.

In order to reduce their consumption, penetrating vapor-permeable soils are usually applied in three steps with a gradual increase in the concentration of the aqueous solution. Here is a step by step guide:

1. When priming in the first pass, the soil is diluted with water in a ratio of 1:4;
2. In the second pass, the concentration increases to 1:2;

1. The third time the wall is treated with an undiluted primer.

Finishing

What is the external finishing of aerated concrete walls after priming?

Cement plaster mixtures of increased vapor permeability. They have sufficient mechanical strength and moisture resistance, while at the same time not interfering with the filtration of water vapor from residential premises to the street.

If you prefer to paint the facade over a primer without prior plastering, use waterproof acrylic, latex or silicone-based facades. All of them have sufficient vapor permeability for our purposes.

The “rubber” water-dispersion paint based on acrylic latex made the most favorable impression on me. It is absolutely impervious to water, which will help protect the facade from precipitation.

What materials can be used for interior finishing of aerated concrete walls? Here the set is quite standard:

• Gypsum plasters and putties;

In the photo - finishing gypsum putty.

• Gypsum board with gypsum adhesive. "Perlfix" or "Volma Montage" perfectly adhere to the surface of aerated concrete blocks after their treatment with the notorious Betocontact or any other adhesive primer.

Conclusion

From the article, you learned about the properties and features of the use of aerated concrete primers used in wall decoration from the inside and outside. In the video in this article, as usual, you can find additional thematic materials. I look forward to your comments and additions. Good luck, comrades!

December 19, 2016

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