Plastering aerated concrete walls inside a residential building is one of the best options to preserve the heat-saving properties of enclosing structures.
The use of aerated concrete blocks as building material– practically perfect option for low-rise housing. Private houses built from them have such advantages as light weight (and, therefore, do not require the construction of very 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 heavier structures. To protect the walls, plastering of aerated concrete walls is required - sometimes external, but most often internal.
Finishing features
When performing internal plastering of aerated concrete, it is worth taking into account the characteristics of this material and the differences from more traditional brick, concrete and stone. First of all, this concerns the cellular structure of the blocks, which were initially considered insulation, and only then began to be used to build the walls themselves. Due to the open structure, which is the result of adding a special gas-forming 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 work on the facade of the building. Changing the order and performing the exterior finishing first, and only then the interior, results in too much high humidity in room. The steam escaping (especially in severe frost) condenses in the walls at the border between aerated concrete and finishing. The moisture created by this can lead to cracks in the plaster and pieces of it falling off. That is why interior finishing work is carried out first.
Selection of method and material
By doing finishing works Plastering aerated concrete walls is done 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, involves complete vapor barrier. The advantages of maintaining vapor permeability are the creation of an optimal microclimate, and the option with wall insulation is the preservation of the exterior finish, which is not affected by the 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, a material with the same or greater vapor permeability compared to aerated concrete is considered. In cement this characteristic is much lower, which does not allow preserving normal conditions inside the building. For the same reason, the answer to the question whether it is possible to plaster polystyrene foam or polystyrene foam will be negative.
In addition, cement-sand mortar has high humidity due to the significant amount of water required for its preparation. Aerated concrete structures, which have a high water absorption rate, absorb liquid from the finishing material. The quality of the mortar, which requires uniform drying to gain strength, is reduced, as is 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 the inside of aerated concrete. Despite the fact that it is designed taking into account the characteristics of the material, it is advisable to apply the adhesive in a thin layer, which is not suitable for protection against cracks. As soon as the vapor permeability of the block is broken, on the surface of thin-layer plaster for aerated concrete glue mixture will appear immediately;
- cracks;
- marks from seams;
- and even mold.
Vapor-permeable finish
When choosing the option of finishing walls made of aerated concrete indoors while maintaining the natural vapor permeability of the material, they use plaster mixtures with gypsum and gypsum putty. Thanks to the slaked lime and perlite sand they contain, 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 used as interior plaster walls made of aerated concrete such mixtures, which contain a high content of such natural materials with a high degree of vapor permeability:
- chalk;
- marble;
- dolomite;
- limestone.
Their vapor permeability rates are higher compared to not only internal, but even external plaster, and the dried solution is easily rubbed down, acquiring perfect whiteness. The resulting coating has excellent durability and allows for 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.
Finishing with vapor barrier
When choosing aerated concrete finishing indoors with the elimination of vapor permeability, that is, with complete insulation of the enclosing structures, one of the materials is polyethylene film. The simplest and quick method fixing it on the walls - laying it under one of the finishing layers. However, the speed and ease of installation do not matter if condensation forms on structures finished in this way and the plaster swells. A more suitable option for plastering aerated concrete inside a house would be a sand-cement mixture, which does not contain additives such as dolomite flour or lime. With its help, vapor permeability is reduced several times, but the possibility of peeling off the plaster after some time increases.
The following will help to further reduce the vapor barrier without affecting the quality of the finish too much:
- oil paint used to cover walls final stage works;
- applying 3–4 layers of a special composition as aerated concrete primer;
- use of adhesives before applying plaster. In this case, you can even do without using putty. Adhesive materials have the same properties and, in fact, replace it.
Features of work
To finish aerated concrete with your own hands, you need to use the same tools that are needed for regular plastering. To prepare the solution plaster mixture you need a special container - such as plastic tank or a bucket made of the same material. Their size should be sufficient to place all the ingredients for plaster inside.
Water is added to the dry mixture that is poured into the tank. The mixture is mixed to the desired state using a drill with an attachment or a construction mixer. As a rule, the proportions of material and liquid can be determined by the inscriptions on packages of building materials.
Plaster of aerated concrete walls is applied indoors by “throwing” it with such tools as:
- Master OK;
- plaster ladle;
- trowel.
The surface is rubbed with a float. And excess mortar can be removed from the wall with a scourer. Leveling the wall is required with the help of beacons, and tightening the plaster mortar is a rule. Another tool that you can’t do without when performing work is a slatting rod with a length from the floor to ceiling. With its help, defects on the walls are checked - deviations of no more than 6–7 mm in size are considered acceptable.
Plastering process
Having decided the question of how to plaster walls made of aerated concrete, they proceed directly to the work. They begin, like all surface finishing methods, with preparing the base. The blocks are cleaned of any remaining mixture and the seams between them are sealed. Before plastering aerated concrete indoors, a layer is applied to the porous surface.
Solutions for aerated concrete blocks, which require maintaining vapor permeability, also
are capable of transmitting steam, distinguished not only by high water-repellent properties, but also by the ability to strengthen enclosing structures. The primer must be applied not in one layer, but in several. In this case, it is necessary to take into account that the new application is carried out only on top of the completely dried old one.
- Fastening the mesh to reinforce the blocks. Due to the large size of each aerated concrete product, their adhesion to finishing materials is small. And to increase strength, reinforcement is used with a material that contains alkali-resistant fiber. Can be used for aerated concrete mesh "chain-link" with small size cells. To fasten it, the use of 120 mm nails is required, which are driven well into aerated concrete;
- If reinforcement is not used (it is necessary to decide whether a mesh is needed when plastering aerated concrete at the stage of selecting materials), the adhesion of the finishing layers to aerated concrete is ensured by grooves intersecting each other, made by any suitable tools- for example, with a hacksaw.
- Applying the first layer of material (pre-selected, the better to plaster aerated concrete) onto the mesh. In this case, the “spraying” technology is used, which ensures complete filling of the aerated concrete cells, and leveling of the first layer is not carried out, which improves adhesion to the next layer of plaster.
When applying a priming solution over rough aerated concrete plaster, it is necessary to maintain the layer thickness at 4–5 mm. It is recommended to add slag sand to the primer. When applying the final plaster layer, it is advisable to use a building material that contains fine sand, which increases the smoothness of the blocks.
Aerated concrete is one of the most common materials in the construction of houses. It is durable and has many other advantages. One of its few drawbacks is its low resistance to moisture. And if it doesn't happen in the warm season big problem, then in winter the moisture that gets inside such a wall after freezing and thawing will begin to gradually destroy the wall. Small cracks will be obvious at first, which will then lead to the problem getting worse.
Why else do you need plaster finishing?
Plastering aerated concrete is a mandatory task when building a house from this material. In this case, it is worth considering the common compositions applicable for this work, a possible algorithm and a common method of finishing a wall with plaster. In addition to protection from moisture, an outer layer for an aerated concrete wall is required for other reasons:
- plaster allows you to retain heat inside the house;
- it has good sound insulation;
- This is an excellent protection for housing from temperature changes;
- a layer of decorative plaster will become good decoration facade.
In order for the material to perform its functions fully, it must be properly prepared and applied. Moreover, not only an experienced craftsman, but also a beginner can do this work with his own hands.
General requirements for choosing a composition for plastering walls
When choosing the type of plaster for a house made of aerated concrete, you should pay attention to the features offered in construction stores compositions. The method of preparation, use and quality of coating will depend on the selected material. Regardless of whether aerated concrete wall plaster is used indoors or for exterior finishing, there are a number of general requirements for the solution used:
- vapor permeability must be higher than that of aerated concrete so that the wall can breathe;
- minimum amount of water required for cooking;
- it is important to pay attention to the minimum and maximum possible layer thickness;
- the adhesion index should not be lower than 0.5 MPa;
- resistance to cold and sudden temperature changes;
- it is important that the solidified solution does not crack under unfavorable conditions;
- for a novice master it will be more convenient to use a solution that can be used for a long time without fear that it will quickly harden.
Choosing internal or external plaster for aerated concrete, it is important to pay attention to these parameters. You should not risk quality for the sake of a favorable price, since the cheapest plaster can reduce all the effort expended to zero.
Cement plaster for aerated concrete
Common plaster mixtures are divided into 3 main types: cement-sand, gypsum and facade. The question is whether it is possible to plaster aerated concrete with any of these solutions.
According to experienced craftsmen, plastering aerated concrete with cement mortar is highly undesirable, although it is a very common material. There are a number of reasons for this. Firstly, the vapor permeability of such a coating will be lower than that of the wall, so the applied layer of plaster on the gas block will not provide sufficient thermal insulation inside the room.
Secondly, aerated block walls are smooth, so adhesion cement-sand mortar will be weak. Even if you add glue to the mixture before starting work, this will have little effect on the result.
Thirdly, plastering of walls made of aerated concrete blocks is done to protect against moisture penetration, but a lot of water is needed to mix the cement composition. And even a layer of primer will not protect the solution from loss of liquid during contact with the wall, and improperly dried plaster begins to fall off the wall due to its own weight and the presence of large fillers in the composition.
Some craftsmen use the following method to solve the problem: they mix dry ingredients with water in a 1:1 ratio to reduce the percentage of liquid in the solution.
This option is not very convenient, because it is necessary to plaster the walls quickly with the composition diluted in this way, before the hardening process begins, and this is not possible for everyone who carries out repairs with their own hands.
Features of gypsum and facade plaster
When plastering aerated concrete walls, the use of gypsum compounds is considered acceptable for several reasons. This solution dries faster than a mixture of cement and sand. It does not shrink. Since the base layer already makes it possible to obtain a flat surface, gypsum plaster does not require a topcoat.
The disadvantages of this composition include the large amount of water required for preparation (up to 15 liters per bag). The vapor permeability of the coating is better than cement plaster, but this indicator cannot be called ideal. If you use the composition for exterior use, it may become wet during rain or snow, and during the drying process there is a risk of stains appearing on the surface, which will have to be corrected to maintain a decent appearance of the house.
According to experts, facade plaster on aerated concrete is the most the best choice for the master. High rates of vapor permeability and adhesion, combined with pleasant external parameters, give this material an advantage over other solutions.
How to choose the right time to start work
Before plastering aerated concrete, the wall must dry thoroughly. If cement mortar was used during the laying of the blocks, the waiting time will be longer than with an adhesive bonding element.
It is worth remembering that such wall material absorbs water, so its external decoration will not be effective during the rainy season. But it will be especially dangerous for walls, cold water turning into ice. When melting, this solid material begins to expand, destroying the structure of aerated concrete.
Therefore, construction must be planned in such a way that it is possible to plaster the aerated block walls between the end of March and September. The main criterion will be the air temperature, which should not be below 0 0 at night.
Algorithm options
Having decided on the best time to plaster the walls, it is important to choose the best sequence of work. It is well known that plastering aerated concrete walls outside is no less important than inside. Therefore, the master has 3 options:
- If the weather outside is expected to be wet for a long time, or the house is located near a lake or river, it makes sense to plaster the outside of the wall first. So, the structure will be protected from moisture from the outside. But, since with one-sided finishing, vapors from the walls go inside the premises, threatening to spoil the repair and destroy the structure, you should not hesitate with the interior finishing.
- Most often, craftsmen begin finishing the walls indoors, since in this case air vapor will not penetrate into the building, and after the interior decoration has completely hardened, they can begin work on the outside of the house.
- Finishing both sides at the same time is the worst option for plastering walls. Since the composition absorbs water from the solution, the wall will still be wet. Only if the moisture does not find a way out, it begins to destroy the wall from the inside.
Although the technology for plastering aerated concrete walls can be chosen at the discretion of the master and depending on the situation, the best result will be when using the second option.
Internal plaster of aerated concrete walls
Before plastering aerated concrete inside the house, it is necessary to rough the wall. It is necessary to remove all existing irregularities, since the thickness of the applied layer depends on this.
Before applying the primer, it is important to wipe the wall from dust with a roller dipped in water. This simple process will prevent you from increasing the amount of water when diluting the solution for interior work, while a properly prepared solution will ensure good adhesion to the wall.
The choice of primer depends on the purpose and degree of humidity of the room. So, for bathrooms and kitchens it is better to take the composition deep penetration, while for a corridor or toilet you can get by with a cheap primer.
So that the plaster for facade or selected type of aerated concrete lies even layer, install beacons. Their vertical evenness is checked using a level, and the installation frequency is determined by a rule.
Since it is necessary to plaster walls made of aerated concrete in several layers, you need to be especially careful with the initial one. It is important that the solution does not deform and does not move away from the wall. If this happens, you need to remove the mixture from the wall and re-prime it.
The first layer of plaster is done by throwing or spraying. The work is carried out from the bottom up. This way the composition is attached to the wall without deforming under its own weight. Additional material is placed in all places where voids have formed.
After the plaster has dried, the layer needs to be slightly moistened. At this stage, you need to remove the beacons, since they will be good conductors of cold into the house. Finally, finishing is used in the form of leveling and painting the walls. This step is optional. If you plan to use wallpaper, finishing is not required.
Features of plaster for exterior finishing
In general, the method of exterior finishing is similar to working inside, but there are some differences in this activity. So, the answer to the question whether a mesh is needed when plastering aerated concrete will be positive. Reinforcement requires material with small cells and a wire diameter of 0.1 mm.
Reinforcement prevents the destruction of the plaster layer during the shrinkage of the building when installed on outside Houses. And it is especially necessary in the area of windows and doors, where such damage is more often observed.
But how to plaster an external wall correctly? After leveling the surface and priming is completed, it is necessary to apply the first thin layer of mortar, into which the prepared mesh should be embedded. This design will be of higher quality than mounting on a dry wall, because it will ensure the greatest fusion of the reinforcement with the mortar. And over the mesh it is necessary to apply the first layer of plaster.
To proceed to the next stage, you must wait until the first layer has completely dried. The time period can be 3-4 days or more depending on the thickness of the layer. To protect against rain, you can cover the walls with polyethylene or other waterproof material. The degree of readiness is checked using water: the dried wall will absorb the liquid.
When applying the second layer, the main emphasis should be on leveling the surface. The third layer is already the finishing layer, followed by grouting or painting the house itself, if necessary.
You can clearly see the process by watching the following video:
The question: is it necessary to plaster aerated concrete blocks becomes resolved for those who know the features and weak sides this material. It's about about the low resistance of such walls to moisture, which is the main reason for the use of protective equipment.
When deciding how to plaster aerated concrete outside and inside, it is worth considering a number of factors: vapor permeability, the amount of liquid in the composition and resistance to negative influences. An important factor is which side you need to start finishing the house from.
A common method allows you to do the work yourself. Knowing the correct sequence, you can perform work on any surface, be it indoor or outer wall. The main thing is to observe the proportions when preparing the solution, give each layer enough time to dry and not continue working if the composition begins to move away from the wall. By following the recommendations of experienced professionals, you can be sure that everything will work out.
Construction of houses from gas silicate blocks is one of the most promising directions in the field of private construction. In particular, aerated concrete blocks have become very popular, during the production of which special additives are introduced into 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 constructed walls. This requires a special approach, both in the sequence of work and in the materials used. In addition, the plastering of aerated concrete walls indoors will also depend on their planned exterior decoration.
What is the “capriciousness” of aerated concrete in matters of finishing, and how can these problems be solved? These are the issues that this publication is devoted to.
Features of aerated concrete
But you should go through the materials for the work in more detail.
- The open porous structure of aerated concrete will not allow you to limit yourself to just filling the walls - a thin layer simply will not stay on such a surface. Therefore, even if the wall is lined with highest precision and does not require special adjustments to its plane - you still can’t 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 subject to cracking and crumbling (affected by the adhesive properties of the highly porous structure) if it is not reinforced with a reinforcing mesh. If on others wall materials the use of reinforcing mesh is desirable, but in the case of aerated concrete this condition should be considered as mandatory. The best mesh is fiberglass, resistant to an alkaline environment, so that over time it simply does not dissolve in the thickness of the hardened plaster mass.
Applications of fiberglass reinforcement stacks - required condition quality plaster - Aerated concrete walls have 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 concrete, which causes it to quickly dry out, crack and crumble - 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 right “humidity balance”, otherwise the work will be of poor quality On the other hand, excessive saturation of aerated concrete with water is also fraught negative consequences. And such a wall is very difficult - the applied solution begins to “creep”, the layer becomes loose or heterogeneous, 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 completely optimized for the characteristics of such a surface and sometimes does not even require preliminary priming of the surface. All this is necessarily indicated by the manufacturer in the instructions for use of the composition.
- use of special deep penetration primers. 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 craftsmen do not advise immediately giving a thick sketch - it is best to limit yourself to a minimum layer in which the reinforcing material is embedded fiberglass mesh. Such a layer does not require a large amount of moisture, it is much easier to “grind” it into aerated concrete with force, and the reinforcement will create a strong base, without cracks. But after such a substrate has dried, you can safely move on to the main plastering on the beacons.
Video: the work of a master plastering an aerated concrete wall
As already mentioned, the composition of the plaster mixture directly depends on whether the wall needs to retain its high vapor-permeable properties, or, conversely, to make it as difficult as possible for moisture to penetrate into the material.
- In the first case, preference is often given to special gypsum-based plastering 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. Classic example similar mixtures - “Plaster” or “Osnovit-Gipswell” plaster.
Manufacturers claim that applying such compounds does not even require a reinforcing mesh. But in the case of aerated concrete, it is better not to ignore this point.
- 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 finishing coating, since silicate mixtures are incompatible with many other decorative compositions on an organic basis - acrylic, silicone, latex, etc.
- Cement-lime based plasters have been developed specifically for aerated concrete or similar surfaces. Their composition is optimized specifically for such surfaces that do not even require preliminary priming before plastering works. An example is Baumit HandPutz plaster or a mixture from a set of a whole “ensemble” of solutions specially designed for AeroStone aerated concrete.
The composition of such plasters includes cement, building lime, special lightweight aggregates and plasticizing additives, and fine-grained purified sand. This coating has good vapor permeability and can be used for both external and internal work on aerated concrete.
- If the owners of the house plan to achieve minimal vapor permeability of the walls from the inside, then they usually resort to using cement-sand plasters without the inclusion of lime or dolomite chips (flour). Naturally, the composition usually includes special plasticizing additives that inhibit the adhesion of the created coating to the porous base.
All specialized mixtures for gas silicate surfaces have one general disadvantage- they are quite expensive, and with large volumes of work, such internal plastering of walls will result in a hefty sum. But this is only preliminary alignment, without taking into account finishing! Is it possible to do something simpler, use more affordable mixtures or even ordinary homemade plaster solutions, for example, based on cement and sand?
It is possible, but such finishing can only be done qualitatively experienced master, whose long-term practice allows him to “by eye” determine the condition of the wall, the need for it to be moistened or primed, and the exact component composition of the plaster. And without experience in such work, making a mistake on an aerated concrete surface is as easy as shelling pears, and all the work will be done down the drain.
However, we can highly recommend interesting way preliminary preparation gas silicate wall to further. If you do everything in accordance with the recommendations, you can apply almost any plaster composition without fear of cracks appearing, the solution slipping, its rapid drying out, or, conversely, excessive waterlogging of the wall.
How can you properly prepare an internal aerated concrete wall for plastering?
To work you will need ordinary, the most inexpensive of all those presented in the store, glue for ceramic tiles, fiberglass mesh, deep penetration primer (regular, type Ceresit CT 17). And then it will be possible to plaster with any composition on gypsum, cement, cement-lime and other bases. In particular, the usual cement-sand mixture, even in a ratio of 1:5, is quite suitable.
Determining in advance the amount of plaster mixture to put the wall in order is quite difficult, 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 you determine the amount of materials for the preparatory cycle.
It takes into account the conditions for priming the surface in two layers, with the primer being diluted with water during the initial application, and the creation of a preparatory reinforced adhesive layer 5 mm thick. Calculations will show the result with a 15% reserve “just in case” accepted among builders and finishers.
The calculation is carried out for rectangular surfaces, minus window and door openings.
Aerated concrete since its appearance in construction industry used exclusively as insulation. Later they began to use it for the construction of partitions. Then the understanding came that it was possible to build from this material load-bearing walls small low-rise buildings. At the same time, a problem arose - how and with what to plaster the aerated concrete walls inside and outside the house. Since aerated concrete products come out of the production line absolutely smooth, it is useless to plaster and putty them with ordinary solutions. These compounds simply do not adhere to the surface of cellular blocks and slide off.
It is also impossible to leave aerated concrete unprotected, since due to its porous structure it is susceptible to atmospheric influences and temperature changes. The cellular structure of this material has endowed it with properties such as high vapor and water permeability. If the first property is useful when performing finishing work, then the ability to absorb moisture should be eliminated. The correct choice of plaster composition will help with this. Plastering technology must also be followed. Inside the house, plastering, puttying and screeding on the floor can only be done in the warm season, in the absence of rain and before facing the walls outside. If you do the opposite and first close the facade, then the fumes from internal “wet” processes will concentrate in the pores of aerated concrete. Subsequently, this can lead to freezing of the supporting structures of the house, the appearance of mold and fungi, and the internal lining will peel off and fall off.
Selection of materials
To level and finish walls made of aerated concrete blocks, it is best to use plaster mixtures designed specifically for such surfaces. This is indicated by the corresponding markings on the packages. The plaster composition must meet the requirements and provide:
- good vapor permeability and ability to repel moisture;
- high adhesion to cellular materials and frost resistance;
- endurance to temperature changes, exposure atmospheric precipitation;
- strength and density of the coating.
A special mixture for aerated concrete surfaces is more expensive than conventional solutions. However, the savings here are not justified. It’s better to pay more than to damage the wall structures and redo the work. Manufacturers offer big choice cement-lime-based materials and gypsum. Each solution has its own characteristics due to the ratio of components and the presence of additives. Recommendations for use of dry mixes from responsible manufacturers are based on practical tests, so they can be trusted. With a quality product it is easy to plaster without much practice.
Among the recommended compositions for interior work, Rotband plaster from trademark Knauf. It is a dry universal plaster mixture consisting of gypsum binder and special additives. Plastering with it is quite easy even with your own hands, with a little skill. The main property of gypsum compositions is environmental safety. They meet all regulatory requirements for use in residential buildings and public buildings.
Mixtures based on cement and lime components can be used both indoors and outdoors. However, when deciding whether to plaster with cement mortar inside, you need to take into account the conditions construction production, and the circumstances of the upcoming operation of the premises.
External plastering of aerated concrete walls
Walls aerated concrete can be plastered on the outside only after all “wet” processes inside the house have been completed. This is one of the main rules for the finishing work of buildings with load-bearing structures from cellular materials. Since aerated concrete walls have the ability to “breathe,” it is necessary to plaster the facade with solutions containing high level vapor permeability. This level should be higher than that of the wall blocks themselves. If this condition is not met, the plaster will trap the steam escaping from the house. The walls inside and outside will become damp with all the ensuing consequences. For finishing, only special plaster for exterior use can be used. The technology for finishing the facade is as follows:
- Preparing the surface of the walls consists of cleaning them from dirt, glue or mortar deposits, sealing seams and large sinks, if any. At this stage, the façade is primed. To improve adhesion, it is necessary to plaster over a primer.
- Reinforcement. This issue is resolved in each case separately. Some experts believe that there is no point in using reinforcing mesh if thin-layer plaster is used for aerated concrete. Although, for greater confidence and reliability of the future coating, it would not hurt to perform reinforcement. To do this, use fiberglass mesh with high resistance to alkalis, placing them on construction adhesive. Plaster mixtures for aerated concrete are alkaline.
- Application plaster solutions. The process is no different from traditional execution. If necessary, use beacons. You can plaster the outside manually or using small-scale mechanization tools ( plastering machines or semi-automatic pistols). The layer thickness in each case is determined separately and can vary from 7 to 15 mm.
- To give appearance a home with a more attractive appearance or special personality is applied decorative plaster or coloring. TO facade paints The same requirements are imposed on the coefficient of vapor permeability.
To increase the service life of the painted coating and maintain comfortable indoor conditions, it is recommended to use water repellents.
Plastering walls indoors
It is necessary to plaster internal surfaces, observing the technology and sequence of work. The procedure itself is standard, just like outside. The main requirements relate to the compositions used. Most often, gypsum-based solutions are used, less often cement solutions with the addition of slaked lime are used. But both of them should have recommendations on the labeling for plastering on aerated concrete. Interior finishing will only be done on a carefully prepared surface. It is cleaned of excess glue or masonry mortar, remove dirt, seal seams. Before plastering, apply several layers of primer. You should use a material intended for aerated concrete, which has increased water-repellent and strengthening properties and is approved for use in interior spaces. The technology is as follows: each subsequent layer of primer is applied after the previous one has completely dried.
If a decision is made to plaster over a reinforcing mesh (this the best option and more reliable), then fiberglass products with increased resistance to alkalis should be used. The mesh must be firmly and evenly attached to the plane. Sometimes, instead of reinforcement, notches are made on aerated concrete, which also help better adhesion inner surface and finishing material. Then you can plaster; applying a rough layer of the composition is recommended using the “spray” method. It would be good to use a plaster gun or machine so that the mixture is supplied under pressure and evenly distributed over the reinforcing mesh. When the plaster mass begins to set, it is smoothed out and primed again. Next comes the process of applying the finishing layer for wallpapering or painting. It can be plastered with textured decorative compounds recommended for covering aerated concrete walls.
Plastering walls made of aerated concrete is a justified measure. , like foam block, despite all its advantages, the material is hygroscopic. This means that it easily absorbs moisture. Therefore, a house made of aerated concrete must be protected from bad weather. If a 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 the aerated concrete will freeze and expand. This is fraught with the appearance of small cracks that spoil the appearance, as well as the occurrence of more serious damage.
Conclusion: protecting 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 external finishing of the facade - plaster for cellular concrete. The main thing is to create conditions for vapor permeability so that the aerated concrete “breathes.”
Exterior finishing of a house made of aerated concrete, in addition to protecting the blocks, allows you to:
- enhance the heat and sound insulation of walls;
- eliminate the possibility of walls getting wet;
- protect the house from sudden temperature changes;
- decorate the facade of the house (decorative plaster for aerated concrete).
One of the most popular methods of exterior finishing of an aerated concrete house is applying 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. Let's carry out comparative review characteristics of the best mixtures for facade finishing, and also describe the technology of plastering walls in the form of step-by-step instructions, understandable to beginners without construction experience.
Plaster for aerated concrete
Having summarized the experience of builders and owners of aerated concrete houses, we can conclude that three types of finishing materials are used for plastering walls made of aerated concrete:
Cement-sand plaster for aerated concrete
Is it possible to plaster aerated concrete with cement mortar?
No you can not. Regardless of whether the aerated blocks were laid with cement or glue. In general, plastering aerated concrete with cement mortar is extremely undesirable, because aerated concrete is very smooth and the mortar does not stick to it, and also strongly absorbs water from the mortar.
Reasons why you cannot plaster a house made of aerated concrete with cement mortar:
- Cement mortar has a lower vapor permeability rate than aerated block. This is the most important reason, why it should not be used. In the case of finishing walls made of aerated concrete, professionals have a rule that you can only use finishing material, which in terms of vapor permeability does not differ from aerated concrete itself or has a higher indicator in comparison with it. Only in this case will the optimal microclimate of the aerated concrete house be maintained.
Note. For the same reason, it is undesirable to use rigid insulation materials (foam plastic and expanded polystyrene) to insulate a house made of aerated concrete.
- Cement-sand mortar has a high moisture content. To mix the components into the sand-cement mixture, you need to add water. It is also obvious that aerated concrete, having a significant moisture absorption rate, will tend to absorb this water from the solution. This, in turn, reduces the quality of the applied solution 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 film to ensure uniform drying. So why should it behave differently on the wall? The primer helps the situation, but not much. The appearance of a web 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 saving necessary, which will significantly reduce the speed of work, and the finished surface will not be of 100% quality.
- U cement mortar for plaster low adhesion. It cannot provide high-quality adhesion to aerated concrete. One of the reasons may be the weight of the solution and the presence of large impurities in its composition.
You can increase the adhesion rate (adhesion, adhesion of surfaces) by adding lime to classic recipe cement mortar (proportion: 8-10 kg of lime per 100 kg of concrete).
Cement-lime plaster can be purchased in the form of a ready-made dry mixture. For example, dry construction cement-lime mixture KREPS Extra-light (240 rubles/25 kg), Osnovit Startwell T-21 (208 rubles/25 kg), Baumit HandPutz 0.6 (300 rubles/25 kg).
- mandatory application of the finishing 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 adhesive?
Also undesirable. Despite the fact that it was developed taking into account the specifics of aerated concrete, it is intended for application in a thin layer and the formation of seams, and not for external wall finishing.
Violation of the vapor permeability of aerated concrete will lead to problems such as cracking of the finishing layer, the appearance of traces of seams (disappear after drying), and the appearance of mold.
Gypsum plaster for aerated concrete
Advantages of gypsum-based plaster:
- high drying speed;
- non-shrinkability of the solution;
- the ability to make a smooth surface;
- no need to apply a finishing layer.
Disadvantages of gypsum plaster:
- mediocre vapor permeability;
- higher water content required for mixing the mixture compared to a special mixture (10-15 liters per bag);
- getting wet quickly during rain or snow;
- the likelihood of stains appearing on the surface that have to be painted over.
Despite the disadvantages, plastering 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
Most efficient material for plastering external and internal walls made of aerated concrete. Plaster for facade work has a number of characteristics, including a vapor permeability indicator identical to that of aerated concrete (for most types of plasters), good adhesion to the base, and a beautiful appearance.
When choosing what to plaster aerated concrete with, it is best to choose 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 plaster is best for plastering aerated concrete walls?
The market offers a variety of ready-made mixtures for plastering aerated concrete walls. 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 mixture);
- boundary values for the thickness of plaster application (minimum and maximum);
- adhesion to the base (minimum 0.5 MPa);
- resistance to low temperatures;
- crack resistance;
- pot life of the solution. The more, the easier it is for beginners to work with it.
And only when choosing between two equivalent mixtures should you be guided by the price; it plays not the last role in this matter, but not the key one either.
According to reviews, plastering walls made of aerated concrete outside the room is popular among users - a dry mixture with plasticizers Ceresit CT 24 (380 rubles/25 kg), the leader in terms of price/quality.
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When can you plaster aerated concrete walls?
Since aerated concrete easily absorbs moisture, it is better to immediately protect it from getting wet. Let us repeat, it is not critical if the material gets wet, but you should not allow the moisture in the aerated block to freeze. This can cause it to weaken and cause unwanted cracks to appear.
There is also no need to rush into cladding. After laying aerated concrete, the walls should dry thoroughly. That is why plastering of aerated concrete walls is carried out only in the warm season. If a concrete-sand mortar is used 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 finishing the house during the warm season is not possible, 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 advisable to cover the walls with polyethylene left over from packaging pallets of aerated concrete.
According to the craftsmen, the most preferable time for finishing work is the period when the night temperature exceeds 0 °C. For middle zone Russia, this time is from the end of March to the beginning of October.
Which side should you start finishing a house made of aerated concrete from?
Let's carry out comparative analysis several popular options for the order of wall finishing.
Option 1
First, the exterior finishing 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 picks up moisture. However, this is not so, even after standing without protection (but primed) for the whole winter, the aerated 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 finishing, but also risk the appearance of cracks inside the room.
Option 2
First, the interior decoration of the house is made from aerated concrete.
With this approach, the pores are partially closed during finishing work. aerated concrete block. And if they are plastered on the outside first, the accumulated water vapor will simply have nowhere to go. Moisture settling inside the block will contribute to its destruction. Plastering aerated concrete walls indoors will avoid this situation.
After the plaster has touched the internal walls and has dried well, you can begin finishing the external walls.
Option 3
Simultaneous finishing of the inside and outside of the house
The method is the least preferred. The moisture that the gas block will “pull” simultaneously from the outside and from the inside will not have the opportunity to quickly escape.
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 condensation and may ultimately 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
The question of whether it is possible to plaster aerated concrete has been sorted out. Now it is important to understand how to do this correctly, without damaging the aerated concrete to allow moisture to pass through.
Plastering aerated concrete blocks is not fundamentally different from performing work of a similar type on other materials. The putty application technology differs only in a few details that will be emphasized.
Internal plaster of aerated concrete walls
Technology for finishing aerated concrete with plaster indoors - sequence of work:
1. Preparing the base
It starts with leveling the walls - removing unevenness is done using a plane or aerated concrete grater. It is recommended to carry out this work at the stage of building a house, but many people neglect it, saving time. In principle, this stage can be omitted, which will lead to a significant increase in mixture consumption and an increase in the thickness of the application layer. In turn, this is fraught with peeling of the plaster and cracks.
2. Applying primer
There are often 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 deep penetration soil, for example, Prospectors (450 rubles/10 l).
3. Installation of beacons
Beacons, as the name suggests, determine the thickness of the solution. They are set to the width of the rule. The accuracy of installation is determined by the building level.
4. Throwing on a “fur coat”
This is the name of the method of applying the first layer of plaster. The work is carried out from the bottom up. Next, you need to rest the rule on the beacons and align (stretch) the sketched layer along them. If voids appear, they must be filled 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 needs to be slightly moistened (with a spray bottle) 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. Formation of corners
To arrange and strengthen the outer corners, a perforated corner with a mesh is used.
7. Finishing
Grouting (if necessary) and painting of aerated concrete walls is carried out. In case of wallpapering, finishing is not required.
Paint for aerated concrete also has requirements regarding vapor permeability. Interior paints based on PVA, latex, acrylic emulsions, organic solvents and cement paints have these properties.
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 RUR/2.8 kg)
How to properly plaster aerated concrete walls - video
External plastering of aerated concrete walls
Decorative plaster of the facade of a house may involve applying plaster for external work in a thick layer (thick-layer finishing) or several layers (thin-layer plaster).
Let's consider a multilayer option for applying thin-layer facade plaster for aerated concrete. Its peculiarity is the creation of three thin (no more than 10 mm) layers.
External plaster application technology:
- 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 mesh;
- 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, steel mesh with a wire diameter of 0.1 mm and a cell pitch of 0.16x0.16 mm (average price 950 rubles/m2 = 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 mesh. 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 embedded in the applied solution using a spatula. It is especially important to install the mesh in high-tension areas, near windows and doors.
Advice. Attaching the mesh to a dry wall will not give any result, because the mesh will be fixed to the base with self-tapping screws. If it is installed on a solution, it will form a monolith with the solution and will move with it.
- leveling the plaster layer along 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 thin-layer application of the solution, you will need to wait 3-4 days. The thicker the layer, the more. You can check whether the layer is dry using water. If you spray it on the wall and the water soaks in, it’s time to get to work.
Note. When the plaster dries, it must be protected from the influence of factors environment(from moisture, snow, rain).
- applying a second layer of plaster. This layer is considered leveling, so increased attention is paid to the evenness of application and the formation of a smooth surface;
- applying the third (finishing) layer of plaster mixture followed by grouting if necessary;
- painting a plastered wall made of aerated concrete or applying a textured plaster mixture, for example, Pobedit-Bark Beetle (340 rubles/25 kg).
For painting aerated concrete, only paints for exterior 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 water repellent. This is a special solution that professionals recommend applying a year after painting, after all facing works. A water repellent will give any surface additional water-repellent properties. The special water repellent 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, similar in purpose, but differing in their composition. All this, facade plaster for aerated concrete, sold in the form ready mixture. Designed for thin-layer finishing of plastered surfaces.
Ready-made silicate plaster, for example, Baumit SilikatTop Kratz Repro 3.0 mm (3,700 RUR/25 kg)
Silicone plaster, for example, Baumit SilikonTop (RUB 3,300/25 kg) 
Acrylic plaster, for example, Ceresit CT 77 (RUB 3,800/25 kg) 
Front "fur coat" Weber.pas akrylat or Weber.pas akrylat Fur coat 615С 1.5mm (1800 RUR/25 kg) Conclusion
By consistently plastering aerated concrete walls and using only vapor-permeable materials, you can ensure a reliable finish that will decorate the facade of the house for many years. And planned repair work will be reduced to periodic painting to restore the color of the paint and eliminate small cracks.
