Aerated concrete blocks - a convenient, lightweight and warm building material for walling. At the same time, its strength allows you to build two-story residential buildings, external walls and partitions in frame structures, any commercial, household and industrial low-rise buildings.
Aerated concrete has two serious drawbacks that require measures to provide additional protection in order to increase the durability and reliability of the building. This is the presence of through channels that can be blown by the wind, and the hygroscopicity of the material, which contributes to the accumulation of moisture and reduce thermal insulation properties. The solution to the first problem is solved by plastering from the inside of the premises, and the second - by installing a moisture-proof facade.
Features of performing plastering work on aerated concrete
When performing plastering walls of aerated concrete indoors, it is necessary to consider:
- Open pores on the surface of the blocks, even with very even masonry, do not allow the use of putty alone as a coating. Processing should be carried out in two stages. This is the initial application of a cement-sand plaster layer and, after that, a finishing putty.
- To strengthen the surface of the walls and increase adhesion, prior to plastering, mandatory impregnation with deep penetrating soil or the use of reinforcing mesh when applying the first layer of plaster is required. In this case, the mesh must be securely fixed to the wall.
- Aerated concrete, unlike brick and concrete, does not have high strength and can be damaged even as a result of not very strong hammer blows. This should be taken into account when laying hidden electrical wiring and pipes before subsequent plastering.
High hygroscopicity of aerated concrete forces to begin plastering work inside the building. Meanwhile, the remaining moisture will leave the solid wall, after which it will be possible to do external plastering or a warmed ventilated facade. If you change the order of work, then part of the moisture will remain inside the blocks, which can lead to a decrease in the thermal insulation properties of the material, and in the worst case, to its destruction.
Plastering materials
Manufacturers of pre-mixed mortars offer for sale a wide variety of dry formulations. Today in stores you can buy materials based on:
- popular cement, lime and gypsum;
- ground silicate blocks - the basis for the preparation of liquid glass;
- expensive silicone compounds;
- cement and fine mineral chips;
- decorative acrylic mixes.
Plastering walls with factory-made materials is less troublesome, but they cost significantly more. With a large amount of work, it is better to prepare the working solution yourself. It will be cheaper, and you will know exactly the composition of the applied coating.
However, it is impossible to use a traditional cement-sand mortar because of the strong porosity of the surface. It will be poorly fixed even with a mesh. The best mixes than plastering walls of aerated concrete inside the house are made on the basis of gypsum or lime. It could be:
- gypsum-lime composition;
- a mixture of gypsum with fine washed sand;
- cement, lime, filler and plasticizer.
The application of these solutions is done on a plaster grid or, if available, sawn holes in the wall with a depth of 2-5 cm.
Consumption of materials
To determine the amount of materials necessary for plastering a wall, it is necessary to multiply its area by the thickness of the layer and decompose the resulting value into the components of the working solution. The thickness of the plaster layer can be precisely determined after the installation of beacons or by a series of measurements on all walls.
It is better to buy a little more materials, by 10-15%. This will ensure that a full range of work is performed, and if there is a small excess, it will still be spent on straightening out individual places after installing outlets, switches, wiring, and other work.
In addition to the constituent components of the stucco mortar, do not forget about the acquisition of metal beacon profiles, soil and a polymer mesh.
Work Tools
To comply with the technology of plastering aerated concrete walls indoors, you will need:
- steady step-ladder or mobile scaffolds;
- bath for pouring soil;
- roller and paint brush;
- plumb and construction level;
- measuring tape 3 or 5 meters;
- two rules 1.5 and 2.5 meters long;
- hammer and chisel;
- a capacious container for the preparation of plaster mortar;
- trowel or trowel;
- wide and medium spatula;
- grater, ironer and fry;
- falcon;
- screwdrivers;
- scissors for metal.
Prepare a small shovel and buckets for water and mortar.
Preparing walls for plaster
After the acquisition of materials and preparation of the tool, you can proceed to the preliminary processing of the surface and prepare it for plastering indoors.
By this time, general construction work should be completed, screed work completed, window and door blocks installed, wiring done, and hidden pipes laid. The surface of the walls under the plaster should be cleaned of all types of contamination. Existing defects should be repaired or chipped.
At the next stage, the walls are covered with soil directly on the grid for two times. This will provide better adhesion (adhesion) of the stucco mixture to aerated concrete. To apply the first layer of soil, the existing composition is diluted with water 1: 1. After drying, a second layer is applied from the calculated flow rate of 160-180 g / m2.
Next, on the wall plane, a polymer stucco mesh is fixed. This can be done with tile glue, type CM11, or with special dowel clamps with a length of at least 15 mm. Fixing to the adhesive is done by spreading the diluted adhesive over the tiles.
The alignment of this layer is carried out with a notched trowel, which will create deepened strips for good adhesion of the stucco with the reinforced adhesive layer. The presence of such a layer allows you to use a solution of any composition used in construction for decoration, but it will cost more.
If necessary, profile metal beacons are installed on a primed or glue-coated surface, indicating the exact position of a flat vertical plane. If the wall is so even, then you can immediately start applying the first plaster layer.
Instructions for applying plaster on aerated concrete walls
The technology of plastering walls from aerated concrete blocks is almost no different from the finishing of other materials. The main difference is the preparatory work, which was described above.
So, how to plaster walls from aerated concrete indoors? The stucco mortar is applied to the wall in two stages: spraying with liquid primer and a coating with final smoothing. The solution should be kneaded in small batches, which can be worked out in 1-2 hours. The finished solution must be kept for 15-20 minutes before use.
The spray solution for reinforced tile adhesive is prepared from sand and cement in a ratio of 1: 2 and diluted with water to a density of liquid sour cream. After that, it is sprayed or sprayed with a thin layer on the surface of the prepared wall. The spray thickness should be within 3-5 mm, but not less than 3.
For the main plaster coatings, the solution is prepared in a ratio of 1: 5. To increase the ductility of the material, it is recommended to add lime, plasticizer or liquid detergent. The coating is applied until the soil has completely dried, preferably at the beginning of the setting of the solution.
The layer is poured onto the surface with a trowel and aligned with the rule. After that, alignment is performed with a trowel, which is moved along the wall in different directions until a smooth surface is obtained.
In preparing the wall for the tiles, the plastering work is completed. If it is planned to stick wallpaper or paint, then the plastered surface after complete drying should be puttied with a special plaster composition.
Putty mortar is applied with spatulas and leveled with a grater, which is moved along the wall in a circular motion. Finishing is best done by sweeping the large rule. This will eliminate the remaining small errors.
The difference in the performance of external wall plastering
There is no big difference in the technology of plastering walls on the outside, but, given the increased negative environmental impact, the ratio of cement to sand on the surface should be less. It is even better to plaster walls from aerated concrete with ready-made plaster mixes for outdoor factory-made work.
Finishing should not be applied on a damp surface or on non-dried aerated concrete. In rainy weather, walls made of aerated concrete blocks must be protected with plastic wrap to prevent excessive moisture penetration.
Technological break between the end of masonry and the beginning of plastering
A number of experts claim that plastering the walls can be done no earlier than six months after the completion of masonry and installation of the roof. However, for this period, for the outer surface of the walls, it is necessary to provide reliable protection against atmospheric moisture. Otherwise, during the onset of frost, the water inside the blocks may freeze and cause destruction of the material.
If the foundation of the house is a monolithic slab foundation, then there is no need to wait for shrinkage. You can start plastering work right away. From all of the above, the question of whether it is necessary to plaster walls from aerated concrete blocks can only be answered in the affirmative.