Improved wall plaster: SNIP

Stucco can be simple, improved and high quality. Contrary to popular belief, these definitions do not refer to material quality, but to technology work and finishing characteristics, which are governed by the requirements and rules of SNiP and GOST. Consider the differences between improved plaster and other types of plastering and the requirements to which it must meet.

Differences between different types of plaster

Doing simple plastering possible in cases where the quality requirements for the finished coating are not too high. This type of finish requires the application of only two layers - spray and soil - and is most often used in non-residential premises.

When medium or high demands are made on wall coverings, improved plastering is performed. It is used in cases where a perfectly smooth base is not required and a structured topcoat will be applied to the plastered surface or

stacked tiles. The technology of work involves the presence of three layers: spray, soil and coatings.

High-quality plaster has a similar application technology, but requires at least one additional layer of soil. A plaster coating of this level allows you to get a surface perfectly aligned vertically and horizontally.

Improved plaster: layer thickness

All requirements for the performance of work and the quality of the resulting coating are described in the document SNiP 3.04.01-87 “Insulating and finishing coatings”.

According to the technology, improved plastering is performed in 3 layers. The thickness of each of them depends on the base material and the solution and is prescribed in the SNiP rules.

1. Spraying is necessary to increase the adhesion of materials. For it, a solution of the consistency of liquid sour cream is used. The thickness of the continuous layer cast on brick or concrete substrates should be within 5 mm. For wooden substrates, the maximum layer thickness is increased to 9 mm, taking into account the shingles or mesh.
2. Soil is used to level the walls. With significant unevenness of the walls, the application of soil in several stages is allowed. The thickness of each individual soil layer should be within 5 mm for mortars based on cement and 7 mm for light compositions based on lime and gypsum.
3. Covering layer is the finishing step of plastering, which is rubbed with a smoothing trowel and serves to obtain a smooth and even coating. Its thickness can be no more than 2 mm. When using decorative plaster, the lining can have a thickness of up to 7 mm.

Tip: technology for performing advanced plastering does not require mandatory use lighthouses, but to facilitate the work on leveling the surface and control the layer thickness, beginners are still recommended to work on beacons.

Each layer it is applied only after the previous one is grasped. The total thickness of the material varies within 2 cm. When this figure needs to be exceeded, a metal mesh is printed on the base. Experts recommend using it also when plastering walls of foam concrete, when working on wood and metal. Reinforcing mesh in all cases helps prevent cracking.

In the current SNiP there is no regulation on fixing the stucco mesh, and its mention in the documents is advisory.

Permissible deviations for improved plaster

In accordance with SNiP 3.04.01-87, plastered surfaces may have deviations that are not a violation of the norm:

• from the vertical and horizontal the coating may have a deviation of not more than 2 mm per 1 m of length;
• over the entire height of the wall, the surface can be deflected by no more than 10 mm;
• slopes of windows and doors, poles, pilasters, husks can be deflected no more than 2 mm from the vertical and horizontal for 1 m length;
• the radius of curved surfaces can be deviated by 7 mm from the value specified in the project (control is carried out using a pattern);
• slope width may differ from the design by 3 mm.

Important! SNiP for improved plaster does not allow the presence of exfoliations, cracks, sinks, efflorescences, as well as visible traces of the tool that was used for grouting.

Quality Requirements for Plaster Compositions Used

Quality control of the used material and mortar is carried out on the basis of GOST 28013—98 “Building solutions. General specifications. "

According to GOST, the solution for improved plaster is required to meet the following requirements:

1. The solution intended for spraying and soil should pass through a mesh with a mesh diameter of 3 mm.
2. The solution for the coating layer should pass through a mesh that has a mesh size of 1.5 mm.
3. The sand used for the preparation of the solution should contain grains whose size does not exceed 2.5 mm in mortars for soil and spray and 1.25 mm for the finish.
4. GOST also regulates such technical parameters as mobility, separability, water retention ability and strength.

An additional requirement of GOST is the presence of a document in the solution, which indicates:

• number and time of preparation;
• brand of solution;
• quantity;
• mobility;
• astringent component;
• standard.

Quality control of plastering

Monitoring compliance with SNiP and GOST is carried out at three stages: at the preparation stage, in the process of work and at the stage of inspection and acceptance of the finished foundation.

For control at the preparatory stage it is necessary:

• check the quality of the solution;
• determine the humidity of the walls and temperature;
• make sure that the walls are cleaned of dirt.

In the process of performing plastering works, verticality and horizontalness are monitored, as well as the quality of the resulting coatings.

At the last stage, the control consists in checking the adhesion strength of the dried mortar to the wall and the quality of the surface that has passed the sanding.