Choosing plaster for different types of walls

The choice of plaster for walls directly affects the stability of the finishing layer, the correctness of the surface geometry and compatibility with subsequent materials. Different types of foundations have different physical and mechanical characteristics, including water absorption, density, vapor permeability and coefficient of thermal expansion. There is no universal composition that works equally effectively on all surfaces, so the selection of plaster requires an assessment of the specific type of wall and operating conditions.

 

The main difference between plaster compositions is the type of binder. Strength indicators, reaction to moisture, vapor permeability and technological requirements during application depend on it.

Cement compositions are used for mineral bases with high bearing capacity. They are characterized by increased density, resistance to moisture and the possibility of use in unheated rooms. Hardening time and set strength depend on the brand of cement, the grain composition of the aggregate and the presence of modifying additives.

Gypsum mixtures are aimed at dry indoor spaces with a controlled microclimate. They are characterized by low weight, high plasticity and a short working interval. Such compositions are sensitive to moisture and are not used on bases with capillary suction.

Lime solutions have low density and high vapor permeability. Combined lime-cement compositions are used to balance strength and diffusion properties when working with porous bases.

The physical properties of the wall determine the requirements for adhesion, elasticity and moisture regime of the plaster layer. Inconsistency of the composition with the characteristics of the base leads to cracking, peeling or violation of the geometry.

Monolithic and prefabricated concrete has low water absorption and a smooth surface. Such foundations require a plaster with high adhesiveness. Most often, cement or polymer-modified compositions are used in combination with adhesive soils with quartz filler.

Technical requirements

The minimum adhesion must correspond to values ​​not lower than 0.4 MPa. The thickness of the layer is regulated by shrinkage tolerances and manufacturer's recommendations.

Ceramic and silicate bricks have different degrees of water absorption. Ceramics require preliminary moistening, silicate blocks - priming. Cement and lime-cement plasters are considered technologically compatible with this type of base.

Aerated concretes are characterized by low density and high vapor permeability. The use of dense cement mortars without modification leads to a violation of the vapor regime of the wall. Light plasters with reduced density and increased diffusion capacity are recommended.

Restrictions during selection

The vapor permeability of the plaster layer should not be lower than the parameters of the base. Exceeding the strength of the solution relative to the block increases the risk of cracks.

Wood is prone to linear deformations in case of changes in humidity and temperature. Direct application of mineral plaster is impossible without intermediate structural layers. Systems with chipboard or board materials reinforcement are used.

In addition to the type of base, operational factors that determine the stability of the plaster layer in real conditions are taken into account.

  • The humidity level of the room and the possibility of direct contact with water
  • The temperature regime and the probability of seasonal changes
  • The required thickness of the leveling layer
  • Compatibility with finishing coatings
  • Speed ​​of work performance and permissible working time
Type of plaster Density, kg/m3 Vapor permeability Recommended basics
Cement 1600-1800 average Concrete, brick
Gypsum 900-1100 low Concrete, brick indoors
Lime-cement 1300-1500 increased Brick, aerated concrete

In practice, cases of choosing a composition without taking into account the physics of the base are common. The use of dense cement solutions on porous blocks leads to the accumulation of moisture in the wall. The use of gypsum mixtures in rooms with variable humidity causes a decrease in the strength of the layer. Ignoring the requirements for surface preparation reduces adhesion, regardless of the quality of the material.

The correct selection of plaster is based on comparing the characteristics of the base and the parameters of the mixture. Manufacturing data, including density, strength class and vapor permeability coefficient, are key guidelines. Practice shows that observing the compatibility of materials reduces the probability of defects and simplifies the subsequent stages of decoration.

Assessment of operating conditions, technical requirements and features of the wall allows plaster to be considered as part of the building system, and not as an isolated material.