Aerated concrete is a material with good thermal insulation performance. Low density is also an advantage and can significantly reduce the load on the foundations. But with all its advantages, foam concrete blocks have several disadvantages. Exterior decoration of the house from aerated concrete should be made of materials with low porosity. This is due to the fact that the wall blocks are unstable to moisture and are able to accumulate it inside themselves. Read more about the construction of houses from aerated concrete.
The process of finishing the building from the outside is started immediately after the completion of the indoor work. It is necessary to strictly observe the technology of the work. Lining is performed by one of the following methods:
- painting using special paint for facade work;
- plastering with compositions for lightweight concrete;
- ventilated facade using various cladding materials (for example, siding or block house);
- the device of a multilayer wall with an external verst of front brick.
Plastering and painting
When choosing compositions for facade decoration it is necessary to take into account the vapor permeability of materials. The hygroscopicity of the walls of the blocks is at a fairly high level. They are able to accumulate moisture, which in the form of steam comes from the room. If the cladding has low vapor permeability and prevents steam from escaping, the walls will be wet. Water in the wall cake will ultimately lead to a decrease in its thermal conductivity, the formation of mold and fungus, and a violation of the bearing capacity.
As compounds for the decoration of the facade will NOT work:
- sand concrete plaster;
- covering film-forming paint.
For building insulation it is not allowed to use polystyrene or extruded polystyrene foambecause they have low permeability to steam and air. Read more about the insulation of a house from aerated concrete.
Decorating a house from aerated concrete can be performed using the following types of plasters:
- silicate;
- silicone;
- mineral.
The latter option requires additional work on painting the facade from the outside. The advantage of the material is maintainability.
Work on painting or plastering walls of blocks is carried out only after a set of preparatory work. The following set of measures is required:
- surface cleaning from dust and various contaminants;
- elimination of small masonry defects with glue for aerated concrete;
- surface leveling with special compounds;
- priming the walls with a layer of 2-3 mm (it is better to choose compositions with strengthening functions and protecting against atmospheric moisture).
The more even the surface becomes the basis for painting or plastering, the less mortar will be required to wall the walls of the blocks from the outside. Materials for decorating a facade from aerated concrete are relatively expensive, so you need to try to minimize their consumption.
When decorating walls with plaster, it is sometimes required to use a special reinforcing mesh. It is required to choose one that is resistant to alkali. The cell dimensions are taken to be approximately 3 mm. For reinforcement, the following recommendations can be made:
- if the total thickness of the plaster layer does not exceed 10 mm, additional reinforcement is not required;
- with a plaster thickness of 10 mm, fiberglass is used for reinforcement;
- the thickness of the finishing layer of 15-20 mm requires the use of a reinforcing metal masking net.
Plastering with a layer of more than 20 mm on aerated concrete is not rational.
The reinforcing mesh is applied to the primer before it hardens. With a spatula or grater, it is pressed into the solution. The surface is leveled and allowed to dry. After drying, proceed to applying the required thickness of the plaster. It depends on the evenness of the base.
Ventilated facade
Decorating a house from aerated concrete using the technology of a ventilated facade allows both lining and insulation. Especially such options are relevant for buildings located in server regions, where even blocks with good thermal insulation performance do not pass through heat engineering.
Mineral wool is used as insulation. It does not interfere with the removal of moisture from the walls. But the heat insulator itself needs protection from moisture. To drain the condensate, an air gap ventilated by external air is used. Its thickness is usually 40 mm. In the area of the cornice there are ventilation openings for the exit of moist air.
The basis for fixing the insulation and material for finishing walls from blocks is the frame. It is made of wooden blocks or light metal profiles. Wood is required to be treated with antiseptic compounds. They prevent the appearance of mold and mildew, rotting of the material.
The external crate to the aerated concrete facade is mounted on:
- long screws (use black as more durable);
- dowels with a plastic stopper not less than 30 mm long;
- special dowels for aerated concrete.
The latter option is preferable because it provides reliable fastening without cold bridges. The most undesirable method of fastening will be self-tapping screws, but in the absence of other possibilities they are used.
The installation step of the frame racks for aerated concrete is recommended to use 40 or 60 cm. But the exact dimensions depend on the width of the insulation. In order not to cut the material along, it is necessary to take into account the dimensions when assigning the distance between the frame elements.
After the base (guides and lathing) under the lining is fixed to special dowels, proceed to the installation of insulation. It is mandatory to provide waterproofing over mineral wool.
The waterproofing material should not allow atmospheric moisture to pass, but have high vapor permeability. It is reasonable to use special vapor diffusion membranes for wall decoration from aerated concrete blocks. They do not interfere with the removal of moisture into the ventilated layer from the side of the insulation. Waterproofing membranes also perform the function of wind protection.
After fixing the insulation and insulation, they begin to hang decoration materials. As the facade cladding can be used:
- block house;
- lining;
- siding;
- fibrolite;
- finished facade systems.
The materials are fastened to the insulation frame in accordance with the manufacturer's instructions and may vary for different types.
Brick facade
For reliable protection of the material of the walls of the blocks from external atmospheric influences, it is better to use front brick. Usually used ceramic material. In the general case, a two-layer wall with a ventilated layer inside is made.
The width of the gap for air circulation is assumed to be at least 30 mm, the optimal thickness will be the size of 40 mm. In the lower part of the wall, special openings are provided for air (air), which are protected by ventilation grilles from clogging. In the area of the eaves of the building (or the parapet when using a flat roof), it is possible for humid air to escape.
Brick is a rather heavy material for the manufacture of facade walls. This type of finish must be taken into account when designing foundations. When used for an existing building, it is better to pre-strengthen the supporting part of the house from blocks. Also, the width of the foundations is assigned taking into account the thickness of the wall with brick cladding. Brick overhangs of more than 30 mm are not allowed.
For the joint work of the outer and inner versts, special flexible connections are used. They are laid in aerated concrete at the construction stage. Instead of flexible ties, thin metal plates can also be used. It is important that the elements are made of steel with a corrosion-resistant coating, the most common option is stainless steel. Galvanized bonds in an alkaline environment are quickly destroyed.
Links are staggered. Horizontal distance is taken equal to 600 mm. It is allowed to vertically arrange the connecting parts at a maximum distance of 500 mm from each other.
Properly executed decoration of the facade walls will reliably protect aerated concrete from external influences. It is necessary to strictly observe the requirements for materials and the technology of their application.