Plaster wall of aerated concrete: the choice of material for

Does plastering walls of aerated concrete have any features? What plastering solutions should I use? What is the order of work desirable to adhere to? Do I need reinforcement? Let's try to answer these questions.

Material Features

Key features of aerated concrete are determined by the method of its production. The porous structure is formed by adding aluminum powder to the solution, which reacts with alkali (and cement is a typical alkaline medium), liberates free hydrogen.

Important: despite the similarity of the appearance of foam and aerated concrete, these two materials differ greatly in their performance characteristics. The main difference is that in aerated concrete pores - open, not interfering with the movement of gases and water vapor.

In addition to the highest vapor permeability, the smooth surface of aerated concrete also influences the plastering process: most plaster solutions simply cannot hold onto it without the use of adhesive primers and / or plastering mesh.

Finally, one more important postulate must be taken into account: the water vapor permeability of the walls must always increase from the inside to the outside. In this case, water vapor will not accumulate in the thickness of the structure, causing its excessive moisture with all the attendant troubles: fungus, condensate, and a fall in insulating capacity.

When finishing it is necessary to consider the limited durability of gas-concrete blocks. However, the opinion of its excessive fragility does not always correspond to reality: it all depends on the brand of material and its characteristic properties.

Goals

What is plastering aerated concrete walls for? Why not just paint them?

Слово «нельзя» здесь несколько неуместно. Покраска кладки практикуется; окрашенные стены выглядят вполне благопристойно и стоят десятилетиями.

Moreover, the oldest houses of aerated concrete were built more than 70 years ago and stand the entire period of operation without any protection from atmospheric influences, without showing any visible signs of destruction.

However, plastering still has a number of advantages against the background of painting or operating bare walls:

• Aerated concrete does not have high impact strength. The plaster layer protects it from mechanical damage.
• High hygroscopicity can lead to waterlogging of the walls not only due to the filtration of moisture from inside the room, but also due to the absorption of rainwater. Lower-permeability plaster will prevent it.
• Finally, the interior of the house often means sticking wallpaper. To glue them over the masonry with relief seams is a dubious idea.

Material selection

What plastering?

The answer depends on which side of the walls we are talking about.

Facade

Key requirements for facade plaster are quite understandable: it must be vapor-permeable and at the same time have waterproofing properties. Typically, cement plaster mortars with the addition of perlite and lime are used for the finishing of aerated concrete; in fact, the materials are positioned by the manufacturer precisely as intended for finishing on aerated concrete blocks.

To reinforce the plaster layer, an alkali-resistant fiberglass mesh with a 5 mm cell and a density of about 160 g / m2 is used. Reinforcement is always necessary, without any exceptions.

The wall is pre-primed with a strengthening acrylic primer, which solves several problems at once:

• Reduces water absorption of plaster from wall material.
• Prevents rainwater penetration through the plaster.
• Improves adhesion of plaster to a smooth base.

After drying the plaster mortar, the final finish can be done in several ways:

• Inexpensive and practical solution - painting with vapor-permeable acrylate dyes.
• Textured decorative plaster (stone, bark beet, etc.) can be used instead of paint or under it.
• Finally, the plaster layer can be simply treated with a silicone water repellent. Without obstructing the movement of steam, it will reduce to almost zero absorption of rain water by the facade.

Interior

But with the internal lining of aerated concrete walls, two solutions are possible, each of which has its own advantages and disadvantages.

Vapor permeable finish

In this case, the same vapor-permeable porous plaster mortars are used; the required ratio of vapor permeability of internal and external finishing is achieved by simply increasing the thickness of the plaster layer from the side of the living room.

The dignity of the solution is obvious: more water vapor can leave the house directly through the walls; if so, the room will never be damp or stuffy. The problem is that the vapor permeability of the exterior finish due to water repellency, re-painting or even simple pollution can lead to water accumulation in the wall.

Steam insulation finish

On the other hand, it is possible to provide an optimal ratio of vapor permeability of wall layers in another way: by deliberately reducing vapor permeability for interior plaster. The use of conventional cement or, where it is more convenient, gypsum plaster solutions will allow to achieve this goal without any problems.

Useful: the vapor permeability of the interior can be reduced and the selection of wallpaper. For example, pasting dense vinyl wallpaper will reduce the wall's ability to filter water vapor by 8-10 times. The price of this finishing material - from 400 rubles per roll.

Technology

Instructions for plastering aerated concrete walls do it yourself differs little from the description of plastering work on any other smooth surfaces. There is only one, but extremely important subtlety. Exterior plastering is carried out after all wet interior work is finished - not only plaster, but also pouring screeds, whitewashing ceilings and even pasting wallpaper.

Why? Yes, simply because otherwise the water contained in glue, mortars and paints will evaporate and be filtered through walls that have not been cut off from the inside. Aerated concrete steam will pass without delay, but the outer plaster layer, much less permeable to steam (even in the case of using special solutions), will delay it.

The consequences are more than predictable:

• Soaked wall holding less heat.
• The appearance of the fungus.
• Separation and cracking of plaster.

How to plaster?

Let's take a more complex way - plastering at the beacons.

1. The wall is cleaned from dust, dirt and debris. It is advisable to at least brush off its entire surface with a brush, it is better to vacuum it.
2. The surface of aerated concrete blocks and seams is primed. Soil is applied with a brush, roller or, more conveniently, spray.
3. A plaster grid is attached to the wall. For fastening, you can use ordinary wood screws: they are screwed into aerated concrete without any problems.
4. A plumb lighthouse profile is set on a plumb line. A small amount of plaster is used to attach them to the wall.
5. After the mortar sets, two or three threads stretch between the profiles. They will serve as a guide for mounting the other profiles in one plane. The step between the profiles should be less than the rule you have (usually it takes 1-1.2 meters).

1. The plaster mortar is prepared according to the recommendations of the manufacturer and is piled on the wall with a trowel in layers of no more than 1 centimeter with pauses to set each layer. The last layer is aligned with the beacon rule.

How to make a hole in a plastered gas-concrete wall or a basement under it, or an opening for communications? Using a perforator under the ban: the probability of chipping and cracking is too high.

The output will be diamond drilling of holes in concrete: it does not require the use of a percussion mode, and the edges of the holes remain perfectly smooth. Cutting reinforced concrete with diamond circles is very convenient also because it does not require changing the circle when passing reinforcement; however, this is relevant only for the basement. Aerated concrete can be cut with an ordinary abrasive wheel.

Alternatives

What can be replaced with plaster in the case of aerated concrete walls?

Most of the alternative solutions used to improve the thermal characteristics of the house. We give some of them.

Conclusion

As it is easy to see, the finishing of aerated concrete walls is not overly complex and quite capable of a beginning builder. The video in this article will traditionally offer the reader additional materials. Successes!