How to plaster aerated concrete outside – features and choice of material

Aerated concrete building exterior plastering necessitates a meticulous method to guarantee longevity and visual appeal. Known for its insulating qualities and low weight, aerated concrete differs from regular concrete in several ways. This implies that the plastering methods and supplies utilized must be especially appropriate for the special qualities of aerated concrete.

Selecting the appropriate plaster type is crucial when plastering aerated concrete. It’s possible that standard plaster mixes won’t adhere correctly or offer the required weather protection. To ensure a strong bond and long-lasting performance, it is imperative to choose a plaster that is compatible with aerated concrete.

Plastering requires not only the right material selection but also the proper preparation of the aerated concrete surface. This entails giving the surface a thorough cleaning, priming it appropriately, and maybe using reinforcing mesh. By taking these precautions, you can help the plaster have a solid base and avoid problems like separation or cracking over time.

Lastly, the actual application method needs to be modified for aerated concrete. The durability and appearance of the finish can be greatly improved by applying the plaster in thin, even layers and giving each coat enough time to dry in between applications. With your aerated concrete structure, you can achieve a long-lasting, high-quality exterior plaster by knowing and using these particular techniques and materials.

Feature	Details
Preparation	Clean and moisten the aerated concrete surface to ensure good adhesion.
Base Coat	Apply a primer to stabilize the surface and improve plaster adherence.
Material Choice	Use a plaster specifically designed for aerated concrete, typically cement-based with additives for flexibility.
Application	Apply the plaster in thin layers, allowing each to dry before adding the next.
Finish	Use a finishing coat to protect against weather and provide a smooth appearance.
Maintenance	Regularly inspect and repair any cracks or damage to maintain the plaster’s integrity.

A little about aerated concrete

The autoclaving process is used in industrial settings to create aerated concrete. Aerated concrete can also be produced without an autoclave by allowing it to solidify into shapes on its own. However, the first choice enables you to create stronger blocks that can be utilized to construct walls that support weight. These are typically D500 and D600 brand structural and heat-insulating blocks.

The ingredients of cellular aerated concrete blocks are quartz sand, lime, water, and aluminum powder, which serves as a blowing agent. Numerous pores are created as a result of the chemical reaction, which also causes gas bubbles to form and disperse throughout the solution.

Positive qualities

Aerated concrete has additional benefits, such as thermal insulation, because air is present in its pores.

1. Aerated concrete is an environmentally friendly “breathing” material, the microcirculation of air in the pores of which can be compared with the same process in the structure of natural wood;
2. Aerated concrete is lightweight, so it does not bear any load on the base. However, the choice of foundation should be approached responsibly – cracks on the surface of aerated concrete masonry appear due to the mobility of the foundation. In this regard, experts recommend installing a monolithic strip base;
3. Aerated concrete is a fire-resistant material and can withstand the effects of open fire for more than 5 hours without contributing to its spread. Aerated concrete blocks can be used for fire protection of metal structures;
4. Frost resistance of aerated concrete blocks is ensured by the distribution of frozen water into free, dry internal pores when the air temperature drops;
5. If you place aerated concrete in water, it will float on its surface, which indicates a certain degree of moisture resistance of the material;
6. Aerated concrete is easy to process and lay, which can be done by one or two people. The block is lightweight, easy to carry, thanks to the end recesses, and its dimensions, exceeding those of a brick, allow you to erect a building quickly and at the same time save mortar.

But when the aerated concrete facade isn’t finished on the outside, some of its advantages become disadvantages.

Nevertheless, since moisture always finds its way through the block’s outer layer, it will eventually start to degrade the aerated concrete masonry. The aerated concrete’s hydrophobicity is what calls for external finishing. Furthermore, a plastered facade has a much nicer appearance. As such, it is not worthwhile to inquire about the necessity of plastering aerated concrete.

When it is necessary to carry out work

Building box construction is followed by the start of finishing work. Experts maintain that aerated concrete plastering needs to be completed indoors prior to doing any exterior work.

There should be a three to four month gap between the facade’s internal and external finishing. External finishing of the facade is only done when it is threatened by intense regular moisture, such as when the house is situated on the bank of a reservoir, prior to plastering aerated concrete inside.

Crucial! It is necessary to wait for approximately six months after the house is built in order for the moisture that accumulated during construction to naturally evaporate from the aerated concrete blocks. For facade work, April through September are thought to be the best months.

Is it necessary to insulate the facade before plastering

Prior to applying aerated concrete, the walls must have their exterior insulation completed. The procedure for using mineral wool as wall insulation is depicted in the image above. The best use for this material is to insulate aerated concrete walls.

First, it’s important to determine if aerated concrete walls require insulation. Its thermal engineering properties and the fact that the wall doesn’t require additional insulation are two advantages of this material.

But it’s crucial to understand that insulation isn’t always required:

1. In conditions where the thickness of the aerated concrete wall does not comply with building codes. When building a house in the middle or northern climate zone of the country, it should be at least 60 cm;
2. Insulation of aerated concrete may be required when connecting blocks of cement-sand mortar – the seams are thicker than with adhesive bonding, and act as cold bridges through which heat is lost.

Crucial! Because of the thin masonry joint created by the use of adhesive, the blocks’ adherence to one another is stronger.

1. Insulation may be required when installing a reinforcing belt and a simple concrete frame, which has a higher thermal conductivity and forms a cold bridge.

Crucial! In houses with heating, increasing the vapor permeability of wall materials should happen from the inside to the outside, per SP 50.13330.2012. This will guarantee that wall structures operate correctly. The plaster layer should have an indicator of 0.12 mg / (m h Pa), with the vapor permeability of aerated concrete ranging from 0.11 to 0.23 mg / (m h Pa). The insulation’s vapor permeability shares the same characteristic.

Because mineral wool has the required vapor permeability, condensation and the development of a dew point are prevented.

Because mineral wool slabs are lightweight, the aerated concrete base is not burdened by them. Furthermore, the adhesive mortar used for their fastening eliminates the need to install a frame or drill holes in the aerated concrete masonry.

Types of plaster for aerated concrete

For outdoor work on surfaces of aerated concrete, there are various varieties of plaster available. The general requirements for plastering compositions for outdoor work must be understood in order to properly plaster aerated concrete.

1. The plaster must be vapor permeable, while its coefficient must be higher than that of the previous material – aerated concrete or insulation;
2. The plaster layer must be frost-resistant, and withstand other environmental influences;
3. The layer must be elastic, so that cracks do not appear on it;
4. The plaster must have a strong adhesion to the aerated concrete surface.

Mineral plaster

How is aerated concrete plastered? Plastering compositions with a mineral base are advised by experts. These are compositions in thin layers designed specifically for aerated concrete finishing. Such a solution is something you can create.

Pre-made compositions are distinguished by the following:

1. Lime;
2. White cement;
3. Marble chips and other fillers.

These plaster compositions have a limited color palette, but painting them is simple. The use of vapor-permeable paints is also crucial. Since this is a weak point for mineral plasters, painting is required to shield such a coating from moisture.

Silicate plaster

The base material for this kind of plaster is potassium liquid glass, which serves as a binding agent.

Among silicate plaster’s benefits are:

1. Ease of application;
2. Moisture resistance;
3. Vapor permeability;
4. Can be painted;
5. Affordable price;
6. Durability – up to 25 years;
7. Decorative.

Silicone plaster

Is it feasible to apply aerated concrete as plaster? Yes, of course! The best material for this is facade silicone plaster, which excels over other plaster options in a wide range of functional and technical aspects.

The following are some advantages of silicone plasters:

1. High water -repellent properties;
2. Application can be performed with your own hands without attracting specialists;
3. High degree of confrontation atmospheric phenomena;
4. Vapor permeability;
5. Durability;
6. Texture and variety of fillers;
7. Elasticity. Thanks to this quality, cracks do not appear on the plaster in aerated concrete.

Complete usage instructions are included on the package for silicone plaster solution, which is sold in its finished state.

Acrylic plaster

Acrylic plaster has high decorative and strength. But a significant minus regarding the use of these compositions is precisely for aerated concrete blocks and other cellular concrete, their low vapor permeability coefficient is. This is the reason for the formation of condensation inside the plaster layer with all the ensuing consequences.

Cement mortar

Is it feasible to use cement mortar from the outside to plaster aerated concrete? The clear response to this query is no. It is important to take a closer look at the reasons why this common material isn’t appropriate for aerated concrete in particular and cellular concrete in particular.

1. Cement mortar does not have sufficient adhesion to reliably adhere to the smooth surface of aerated concrete. If cement plaster is used on aerated concrete – the video in this article clearly demonstrates the consequences. This is due to the high weight and density of the solution;
2. In addition, aerated concrete is saturated with moisture from the cement mortar, weakening its adhesion to the surface, and disrupting its integrity as a result of uneven rapid drying;
3. Low level of vapor permeability of cement mortar leads to non-compliance with building codes and violation of optimal microclimatic indicators in a residential area. But if cement plaster is used for interior decoration, it will protect aerated concrete from steam penetration into the thickness of the walls.

Crucial! Foam plastic and expanded polystyrene are not suitable materials to cover the surface of aerated concrete.

To ensure durability and aesthetic appeal, extra care must be taken in the materials and techniques used when plastering the exterior of aerated concrete. Because of its insulating qualities and light weight, aerated concrete requires a flexible, breathable plaster that can withstand weather and adhere well. In order to avoid problems like cracking and moisture penetration, choosing the proper plaster requires choosing materials that take into account the special characteristics of aerated concrete. The essential procedures and factors to take into account when plastering aerated concrete exteriors will be discussed in this guide, guaranteeing a durable and appealing finish.

Calculation of cement mortar

The most common plaster mixes for aerated concrete

When working with aerated concrete, a number of facade plaster compositions have shown to be effective:

Types of plaster

Decorative facade plaster

• suitable for application to mineral wool slab insulation;
• suitable for painting;
• has high decorativeness;
• vapor-permeable;
• has low consumption;
• durable and resistant to various influences.

• high adhesion;
• moisture resistance;
• does not shrink;
• high frost resistance;
• can be used at low temperatures.

• high plasticity;
• increased adhesion;
• strength;
• dirt-repellent properties;
• water-repellent properties;
• variety of color solutions;
• decorative.

• granularity;
• color variety;
• vapor permeability;
• high density;
• strength;
• moisture resistance.

The proper selection of materials and meticulous attention to detail are necessary when plastering aerated concrete on the exterior. Because it is a porous and lightweight material, aerated concrete requires extra care to produce a finish that is both long-lasting and aesthetically pleasing. You can improve the building’s aesthetic appeal and protect its exterior by taking the right precautions.

It’s crucial to pick a plaster that works well with aerated concrete when choosing materials. This typically entails choosing a plaster that is breathable and capable of efficiently controlling moisture to avoid problems like peeling and cracking. Plasters with mineral bases are frequently a good option because they are breathable and durable.

The preparation of the surface, the primer application, and the careful plaster layering are the three main steps in the application process. For the plaster to adhere correctly and offer long-lasting protection, each of these procedures is essential. A smooth and even finish requires careful application and adequate preparation.

To sum up, careful planning and execution are necessary when plastering aerated concrete. You can obtain a superior finish that both protects and enhances the appearance of your building by choosing the appropriate materials and applying them according to the suggested methods. These recommendations will support you in getting the greatest outcomes whether you’re building a new project from scratch or remodeling an old one.

Video on the topic

What can be used to plaster aerated concrete? We tell you how to choose the right material. #repair

Finishing the facade of an aerated concrete cottage without insulation (bark beetle, fur coat and other textures)

Gypsum plaster or cement? How to choose plaster for interior work.