How to plaster aerated concrete outside and inside the house?

Recently, aerated concrete has been used in the construction of private houses. The material has earned wide recognition due to its positive qualities. Such material is produced in rather voluminous blocks of light weight, so construction is being carried out at a rapid pace..


The foam material perfectly retains heat, therefore, you can significantly save on insulation.

The abundance of pores allows the blocks to “breathe”. The bad thing is that they absorb moisture. If in the warm season the water dries up without consequences, then in frost the moisture absorbed into the building material will inevitably lead to the formation of cracks.

Plastering aerated concrete will prevent the penetration of water into the block, preserve its integrity.

For high-quality performance of work, it is necessary to take into account the features inherent in the material being processed.. Not all aerated concrete blocks are the same – their structure may differ. For example, the outer surface is different.

Plastering sawn aerated concrete can be done without pretreatment. The molded block has a smooth hydrophobic layer on the outside. It is problematic to apply plaster on such a surface – to increase adhesion, you need to grind the treated side with a metal brush.

We must not forget that the degree of vapor permeability increases in the direction from the inner surface to the outer, therefore, the facade finishing should be done twice as thin as the inner coating..

Before plastering aerated concrete walls after construction, at least six months must pass. During this time, the walls will completely dry out, from them excess moisture that gets into the blocks during the construction of the structure will disappear.

The outer surfaces of the walls can be plastered with decorative materials; compositions for subsequent painting can also be used. Exterior decoration sometimes serves as additional insulation. In cold climates, plastering plays a significant role in keeping indoor warmth..

For aerated concrete, you should choose a plaster with optimal parameters. The finishing material must protect the walls from destruction on both sides.

Due to the porosity, aerated concrete received characteristics such as thermal insulation and vapor permeability..

Correctly executed finishing:

  • helps to maintain the useful qualities of the blocks;
  • does not allow condensate to accumulate inside the pores;
  • prevents mold and unwanted damage.

Types and compositions

It is impossible to finish aerated concrete walls with ordinary cement mortar. Standard solutions have too high a density, so they do not adhere well to blocks. Due to poor adhesion, after a short time, cracks appear on the walls, which leads to peeling of the plaster layer and exposing the walls.

Special “breathable” mixtures with a so-called vapor-permeable base:

  • pass steam freely;
  • create a positive indoor climate;
  • protect walls from moisture accumulation inside them.

The following requirements are imposed on plasters for finishing aerated concrete:

  • resistance to precipitation and ultraviolet light, to rapid and frequent changes in outdoor temperature;
  • sufficient density;
  • possessing high adhesion;
  • the presence of vapor permeability;
  • compressive strength;
  • good thermal insulation;
  • decorative appearance.

Good plaster meets all of the above requirements. It is easy to apply, looks great and lasts a long time on the walls.

If the facade is not processed, then the aerated concrete will first darken, then it will begin to deform, and its outer part will peel off.

    Exterior plasters differ from those used for interior decoration of aerated concrete blocks. The former are more expensive, the latter are cheaper. The main difference lies in the moisture resistance of the hardened mixture. If for external walls this indicator is essential, then for interior decoration you can do without it.. The exception is plaster for rooms with high humidity., such as bathrooms.

    By their composition, facade plasters are divided into the following types:

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

    None of the species can be considered ideal – each species has its own strengths and weaknesses. For example, the vapor permeability of acrylic-based plaster is low, but it has excellent decorative properties. The finish is thin-layered, but very durable. The layer retains a flawless structure for a long time.

    It is advisable to use acrylic plaster when applying good insulation to internal walls.

    The basis of silicate plaster intended for aerated concrete is liquid potassium glass. The vapor-permeable coating is resistant to moisture, perfectly resists abrasion and dirt. Durability is a quarter of a century. The disadvantages include the limited color gamut.

    Silicone compounds contain organosilicon polymers and resins. The coating is very durable. Unlike other types, silicone plaster retains its elasticity after hardening. Cracks do not appear on the finishing layer even after the blocks have shrunk. Due to fillers, plaster is given various colors and shades.

    Benefits have a significant impact on cost – silicone compounds are the most expensive.

    Lime-cement mortars are characterized by vapor permeability and strength. They lack elasticity and water resistance. The problem is solved by introducing special additives into the mixture., and experimenting with fillers, you can get different colors.

    Ready-made mixtures are equipped with everything necessary – they can be used without preliminary preparation and introduction of improving components.

    For internal work, completely different compositions are used.. At the heart of the plaster for the treatment of aerated concrete indoors, there is gypsum.

    Before starting work, the blocks should be primed.

    The plaster is applied on a leveled surface, free from build-ups, dirt and dust.

    The work is performed in several stages:

    • padding;
    • applying the first layer of plaster;
    • installation of a reinforcing mesh;
    • applying a second layer of plaster.

    Wallpaper can be glued to the treated wall after the material has completely dried. Decorative finishing can be done on request. The decor appears when fillers in the form of marble chips or perlite are introduced into the gypsum mixture. Wall covered with plaster can be painted.


    It is very important that the aerated concrete walls are prepared for the application of the finishing layer..

    Despite the fact that the outer and inner parts of the wall are used in different conditions, there are general requirements for their preliminary processing:

    • both inside and outside the walls should be even;
    • for both sides, the plaster should be selected with the maximum adhesion capacity;
    • applying the solution to the mesh is desirable on both sides;
    • the master will need a container for mortar, a trowel, a plastering bucket, a grater.

    In order for the plaster to fit well on the gas blocks, the latter should be evenly moistened. For this, ordinary tap water and the simplest spray bottle are suitable..

    If there are chips or cracks, then you will have to pick up a trowel and use a solution to eliminate the flaws. The cementitious mortar is an excellent restorative material if the recesses are first primed.

    With the help of beacons, the surface of the walls of the room is displayed in one plane, after which you can start performing the main work.

    First, finishing is carried out inside the premises and only then outside – otherwise excessive moisture will form inside the house..

    Application technology

    The appearance of the treated walls and the durability of the decorative layer depend on the correct implementation of the technology..

    Below is the sequence of processing the outer surfaces of aerated concrete walls.

    First you need to inspect the blocks: eliminate all irregularities, clean the cracks, expand and putty with ordinary mortar.

    They act in the same way when detecting chips and potholes in each gas block. The listed preparatory work can be done by hand – it’s not difficult at all.

    Those who dare to do basic work with their own hands without the appropriate skills need:

    • acquire tools;
    • follow the technology for performing plastering;
    • not be afraid of heights (part of the time will have to be spent at a decent height in the forests);
    • have free time;
    • have physical strength.

    In order for the plaster to fit well and not lag behind, the gas blocks are primed after cleaning with a metal brush.

      A special primer is required – it must contain acrylatesiloxane. This ingredient protects the wall from moisture and increases adhesion. At the same time, the composition does not interfere with the gas block “breathing”.

      The priming operation in accordance with the technology should be carried out in dry weather and an ambient temperature of about +15 degrees. It is advisable to process the walls from the side where there is no direct sunlight.

      The next stage – mesh tension – is started after the final absorption of the primer..

      A mesh made of alkali-resistant material is suitable for gas blocks. Any other material will simply dissolve over time, which will negatively affect the service life of the finishing layer. On the wall, a fiberglass reinforcing mesh is fixed with self-tapping screws so that a small space remains between it and the wall.

      Plastic plaster specially designed for aerated concrete is applied to the prepared wall in dry warm weather. Mixes for foam building material are quite expensive, but they repel moisture and allow air to pass through. The plaster is applied to the blocks with a wide trowel. The result should be an even thin layer, the thickness of which is approximately 8 mm..

      The processing does not end there.. A water repellent is applied to the plaster. After it has been absorbed, it is time for the final finishing. The choice can be decorative plaster or paint. In both cases, the formulations are distinguished by “breathing” properties, guaranteeing the unimpeded passage of vapors from the inside to the outside..

      The processing of aerated concrete walls inside the house begins in the same way as outside. Inspection is carried out in the same way, and significant deficiencies are canceled.. Before puttingty the surfaces, the leveled wall is primed.

      Interior finishing is carried out with special plaster, which includes gypsum and perlite sand.

      After completing the work, the walls become uniform, smooth, without the slightest visible defects. The plaster consumption is low, because the layer is applied very thin. This eliminates the need for long-term alignment, which is also important..

      Interior walls should be painted with paints specially designed for aerated concrete. They can be applied to both ordinary plaster and decorative. Painted surfaces look great – decorative finish retains its original appearance for a long time.

      When plastering houses from aerated concrete, you need to adhere to the established sequence: first, the walls inside the house are processed and only then from the street. The optimal humidity regime for porous walls is achieved by holding a certain time after the completion of the internal plastering.

      The most favorable time for finishing work inside the house is spring.. The aging period depends on the climatic conditions. As a result, the walls should dry out after “wet” work so that the humidity is no more than 27%. The indicator will be ensured if the exterior finish is carried out at the end of summer..

      Tips & Tricks

      When a wall of aerated concrete is in the bathroom, and it is planned to lay tiles on it, experts advise to proceed as follows.

      First you need to align the wall, make it look like a flat smooth plane. The best way to level it is by plastering, for example with a rotband. Is a gypsum plaster sold as a dry powder. It is perfectly suited for interior work on porous walls..

      Before performing work, do not forget to prime the work surface well. After the plaster has dried, the walls must be treated with a coating waterproofing. Now you can glue the tiles. Suitable adhesive – Ceresit 117.

      Correctly selected mortar guarantees long-term service of the finishing layer. The mixture must have good adhesion and impact resistance..

      Outside air temperature during work should not be below +6 and above +26 degrees. As for the humidity of the outside air, this indicator should strive for 50%.

      Experts recommend applying a hydrophobic solution to the surface a year after plastering the facade – such actions will significantly increase the ability of the walls to resist rain flows and melt water.

      You should not save on plaster, because not only the beauty of the visible part of the building depends on it, but also how long the house will last.

      For how to plaster aerated concrete, see the next video.

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