Plastering aerated concrete: we analyze the technology of plastering the facade and interior spaces

Because of the special qualities of the material, plastering aerated concrete can be a little challenging. Because aerated concrete is lightweight, porous, and highly absorbent, a particular method must be used to guarantee a long-lasting finish.

The proper plastering techniques are essential whether working on the inside or outside of a building. A lasting and appealing outcome can be achieved with careful planning and the right selection of materials.

We’ll walk you through the process of plastering aerated concrete, both for facades and interior spaces, in this post. You’ll discover how to complete the task correctly, from surface preparation to the last coat.

Because aerated concrete is porous, plastering it calls for a particular method that will guarantee longevity and a smooth surface for both exteriors and interiors. Knowing which techniques, materials, and application methods to use will help you achieve a professional-looking, surface-enhancing and protecting finish.

What is the best way to plaster aerated concrete outside

Plastering is one method used to finish walls composed of aerated concrete blocks. Only vapor-permeable plaster is appropriate when taking the material’s characteristics into account. Plastering walls does not lend itself to regular cement mortar. Under it, aerated concrete "does not breathe." Although gypsum mixtures don’t offer the right coating properties, they can theoretically be used for outdoor work.

Special facade plasters are the best option for external finishing aerated concrete walls.

Features to consider when making a decision:

• Vapor permeability. This is the most important indicator when choosing a plaster mix for exterior finishing of gas blocks. It must correspond to the vapor permeability of aerated concrete.
• Compressive strength. This parameter indicates the degree of resistance of the material to destruction, the higher it is, the better.
• Adhesion strength (adhesion). For finishing walls made of aerated concrete blocks, plasters are suitable for which this indicator is from 0.5 MPa.
• Frost resistance. For exterior wall finishing, the number of freeze-thaw cycles that the material can withstand without visible signs of destruction is of particular importance. For plasters, it ranges from 25 to 100.
• Volatile life of the solution. If the plastering of the walls is carried out by an inexperienced craftsman, then the longer the solution in the container does not dry out, the better.

Well-known plaster brands for exterior wall finishing made of aerated concrete blocks include Ceresit CT 24, "Mask," Knauf Grunband, Osnovit Starwell, and others.

Preparation of facade walls

It is preferable to complete all "wet" interior work, such as pouring screed, whitewashing the ceiling, gluing wallpaper, or plastering the walls from the inside, before applying plaster mixture to the exterior of gas block walls. This is required to give the concrete blocks’ pores enough time to let out all of the moisture.

In order to apply plaster, prepare the surface as follows:

1. Clean the wall from dust, dirt.
2. Sand the surface to ensure the best adhesion.
3. Apply a primer for aerated concrete, intended for external work (these compounds have higher vapor permeability).

Aerated concrete primer

1. Work should be carried out at a positive air temperature.
2. It is necessary to use protective gloves.
3. For the first layer, dilute the primer with water in a ratio of 1:4. Apply it with a roller, wide brush or spray.
4. After the first layer has been absorbed and completely dried, apply the second one. The primer is diluted in a ratio of 1:2.
5. Apply the last (finishing) layer after the second one has dried. Do not dilute the primer.

DIY exterior finishing

The plaster mixture is applied in three layers, per SNiP:

1. splash (starting) – plaster thickness from 3 to 9 mm;
2. primer (leveling) – from 7 to 9 mm (if the composition contains gypsum, then up to 12 mm);
3. cover (finishing) – thin-layer plaster from 2 to 4 mm.

Tools for work

• beacon plaster profiles (guides);
• bubble level;
• container for preparing the solution;
• spatula;
• plastering ladle or hawk;
• trowel;
• rule (instead of it, you can make a template with your own hands);
• trowel;
• float for grouting.

Plastering technology

1. Attach the plaster mesh to the wall surface with screws, which is needed to reinforce the starting layer.
2. Glue the extreme beacons (guides made of metal profile) with small portions of mortar.
3. Check the correctness of their position with a level.
4. Pull two – three threads between the initial beacons.
5. Install the rest of the guides along the threads with a step slightly smaller than the width of the rule (about 1 m).
6. Sketch the coil to the surface with the coil plaster mixture. Close it with the rule, moving it with a zigzag by lighthouses.
7. After the solution dries, the verticality of the walls is checked using the rule. If necessary, a leveling layer is applied. The previous layer should be dry (usually it takes 1-2 days).
8. After the finish layer is completely dry, the plaster is wiped with a special grater, pressing it tightly to the surface. The walls are treated twice – in circular motions clockwise, then in a straight line. To achieve perfectly smoothness, the grater can be wrapped with felt or felt and once again treated with it dry plaster.

You can plaster the walls in the same manner if the exterior of the house is insulated with mineral wool. A solution of adhesive is used to attach the mesh to the layer of insulation. After that, continue as you would with ordinary plastering.

Plastering aerated concrete indoors

The type of insulation and the material used for the facade should be taken into account when selecting a plaster mix for interior repairs in a home built with aerated concrete blocks. It’s best not to let moisture build up inside the aerated concrete.

Dense mixtures that keep moisture out must be chosen from the inside if the exterior coating is composed of materials with low vapor permeability.

Any additional finishing that is applied on top of the plaster needs to be moisture-resistant. Plastering the interior of a building with good vapor permeability requires that the materials used for the outside walls have similar qualities.

Several plaster brands for interior work with aerated concrete are:

• Osnovit Gipswell;
• Bonolit;
• Volma Lux;
• Litoks, etc.

A durable and beautiful finish can only be achieved by carefully attending to every detail when plastering aerated concrete. For long-lasting results, using the proper techniques is crucial when working on interior spaces or the facade.

Plaster adheres more readily to surfaces that have been thoroughly cleaned and primed. A key factor in the project’s success is choosing the right kind of plaster for the particular setting, whether it be indoor or outdoor.

By following the specified procedures, you can obtain a level and smooth surface that improves the look of your building and gives the aerated concrete more protection.

Video on the topic

Plaster without insulation of the facades of a house built from aerated concrete blocks, a base reinforcing layer

Finishing the facade of a gas-concrete cottage without insulation (bark beetle, fur coat and other textures)

Technology for finishing the facade of gas-concrete without insulation. Decorative plaster CERESIT st174