Despite the fact that there are several possible ways to decorate the walls in the bathroom, the most common traditionally remains moisture-resistant plaster for painting and tile. The functional feature of the bathroom is increased humidity, which determines the requirements for the materials used and the quality of work.
Types of plaster for walls in the bathroom
Aligning the surface with a plaster layer allows you to eliminate bumps that immediately appear and are clearly visible after painting. Therefore, the walls for painting should be plastered and well dried. In the case of laying ceramic tiles, the plaster layer is sometimes discarded. However, in this case, the thickness of the adhesive layer increases, which leads to:
- rise in price of materials required for finishing;
- shrinkage of glue during setting and violation of the flat plane of the wall;
- complication of the process of laying tiles, which begins to "float" on a thick layer of glue.
Therefore, the rejection of the device for leveling the plaster layer under the tile is possible only if the initial surface of the wall is as even as possible.
Manufacturers of building materials have long been offering for sale a large number of ready-made stucco mixtures, which before use can only be diluted with water. However, all of them are prepared on the basis of gypsum and cement binders with different ratios of constituent components.
Gypsum plaster mixes
The main astringent component of gypsum mixtures is heat-treated and ground natural mineral. As a result of production, the substance can take the form of a fine powder with a fibrous structure, which is called gypsum, or a larger material with granular granules - alabaster.
The main virtues gypsum plasters consist in high adhesion (adhesion to the wall material), ductility and affordable cost. Simple leveling and grinding of the surface allows you to abandon the finishing putty before painting or wallpapering. Only gypsum mixes allow the application of a plaster layer with a thickness of up to 60 mm in one pass.
Main disadvantage gypsum consists in the porous structure of the material, which leads to increased ability of the plaster to absorb moisture and the formation of pores inside the applied layer.
However, to improve the performance characteristics of gypsum mixtures, manufacturers began to add synthetic and natural fillers, as well as polymer additives to their composition to reduce the moisture absorption of the dry layer.
A layer of ceramic tile or waterproof paint, with preliminary priming, will also provide sufficient protection of gypsum plaster from destruction under the influence of moisture. therefore the use of modern plaster mixes based on gypsum binders is acceptable for the bathroom.
In the building materials market, several types of deep penetrating primers are sold to protect the porous gypsum-based plaster layer. Application of such processing:
- creates a waterproof layer on the surface up to 20 mm thick;
- strengthens the plaster, increasing its strength and mechanical stability;
- improves adhesion with glue when laying ceramic tiles;
- protects the finish from possible fungal formations.
An important point when laying tiles is the quality of sealing joints and the use of waterproof solutions for this.
Cement plaster
The main components of cement plaster mixes are Portland cement, fine washed sand and a plasticizer in the form of ground lime or gypsum. Among the main merits such compositions can be noted:
- it is moisture resistant plaster for the bathroom;
- increased waterproofing properties of the material;
- high strength, durability, ability to withstand mechanical and weight loads;
- affordable cost;
- ecological cleanliness and safety.
A long setting time allows you to prepare and use in work a greater amount of the finished mixture than in the case of gypsum compositions. The presence of plasticizers increases the plasticity of the solution and the quality of the result. Moisture-resistant gypsum plaster for the bathroom is sold in stores, but its cost is much higher than that of traditional materials.
In list disadvantages cement plaster experts note:
- poor adhesion of the material to concrete surfaces without additional processing with special compounds;
- increase in time of work due to prolonged setting;
- the need for finishing putty before painting.
Cement plaster is the best material for wall decoration in rooms with high humidity.
The choice of plaster for the bathroom
When determining the type of material for performing plastering in the bathroom, it is necessary, first of all, to take into account the increased humidity in the room when it is used for its intended purpose. Requires waterproof plaster for the bathroom. Therefore, the main requirements for plaster are:
- moisture resistance;
- resistance to sudden changes in temperature;
- resistance to the formation of fungus and mold in wet conditions;
- environmental safety.
A very important factor is the type of finish. The tile provides additional waterproofing, unlike a paint layer.
Stucco
Ceramic tile on the surface of the plaster layer protects it well from moisture. Therefore, in this case, to smooth the surface of the walls, you can apply both gypsum and cementitious compounds.
However, it should be noted that the strength of the gypsum layer, in contrast to the cement layer, is slightly lower. In order to guarantee that the possibility of coating failure due to the large weight of the ceramic is guaranteed, the surface of the plaster layer must be covered with deep penetrating primer or primer at least 2 times.
At the same time, cement plastering of walls in a bathroom under a tile requires finishing by puttying, which makes the surface perfectly even and additionally fixes the surface layer. However, a number of experts do not consider this work mandatory.
Alignment of walls for painting
Painting a surface requires a perfectly even condition. A thin layer of paint instantly shows all the bumps, scratches, cracks, sinks. To obtain high-quality plastering of walls in the bathroom for painting, it is necessary to finish the putty on the plastered surface, and possibly polish it.
It is easiest to get a flat surface using gypsum mixtures. However, a thin layer of paint is not able to provide sufficient mechanical strength. The slightest damage in the form of dents or cracks leads to the penetration of moisture into the plaster layer and its subsequent destruction.
When answering the question of which plaster to choose for the bathroom, you need to understand that plastering for painting is possible only with cement compounds. Their strength and moisture resistance will ensure the longevity of the paint and its beautiful appearance.
To prepare the walls for painting, you should abandon the use of gypsum and use only cement. Among the best cement-based plasters for the bathroom, experts name the materials of the Knauf (Knauf) and Ceresit (Ceresit) brands.
Instructions for plastering the walls of the bathroom
Technologically, the process of leveling the walls in the bathroom is no different from plaster in other rooms. The main feature is the correct determination of which plaster is best for the bathroom under the tile and paint.
The material must be moisture resistant and durable. The best option is to use cement-based mixtures. In some cases, while providing additional waterproofing, the use of compositions based on gypsum binders is allowed.
Wall plastering with cement-sand mixtures is carried out in several successive stages:
- completely remove the old finish, if any;
- repair existing cracks, chips, individual cavities and other defects with the help of “cement milk” or grout;
- treat the concrete surface with a special concrete-contact fluid, for bricks and the remains of the old plaster 2 layers of deeply penetrating soil or primer are enough;
- using a laser level or an ordinary plumb line, determine the places of maximum deviation of the wall surface from the vertical;
- in the most prominent places add 30 mm (the minimum layer of plaster) and draw with chalk lines on the floor and adjacent walls corresponding to these distances;
- when preparing a wall for painting, it is recommended to install beacons that can be fixed vertically using an ordinary building level and focusing on drawn lines;
- when plastering under tiles, a small area of the wall allows you to refuse to install beacons, alignment to provide tiled material;
- after determining the thickness of the plaster layer, you can go and buy the necessary material, since you can calculate its amount.
After acquiring the components for the preparation of the stucco mortar or the finished dry mix, m you can start applying the plaster to the surface. This is done in the following sequence:
- the first layer is called spray and is performed with a thin layer of a liquid solution with a sand to cement ratio of 1: 1;
- after setting the spray layer, which serves to improve the adhesion of the stucco layer to the wall, apply a leveling layer of an average thickness of 30 mm, a minimum layer of 10 mm, a maximum of 50 mm;
- if a 50 mm plaster is not enough to get a smooth surface, then the second layer can be applied only after the previous one has set;
- when finishing with ceramic tiles, plastering work on this end;
- painting the wall requires additional putty and polishing of the top layer.
Plastering walls for laying tiles or painting is an important technological part of the work, which will ensure the strength and durability of the finish.