Construction of load-bearing walls in a house made of aerated concrete: requirements and features of masonry

When constructing load-bearing walls in a home made of aerated concrete, particular specifications and methods must be closely followed. Aerated concrete is a common material in contemporary construction because of its energy efficiency and durability. It is also known for being lightweight and insulating.

Following local building codes and manufacturer specifications is essential when building load-bearing walls using aerated concrete blocks. Although these blocks are intended to support structural loads, strength and stability must be ensured by using proper masonry techniques.

Aerated concrete blocks are laid using mortar that has been specially made for this material as part of the masonry process. Aerated concrete blocks are porous, in contrast to regular bricks or concrete blocks, which has an impact on how mortar sets and adheres during construction.

The capacity of aerated concrete to offer thermal insulation is one of its primary characteristics, and this capacity can have an impact on the energy-efficient design and construction of walls. To get the most out of using aerated concrete, proper insulation considerations need to be incorporated into the wall construction.

Aerated concrete is beneficial for both new construction and renovation projects because it is lighter than heavier materials, which makes handling and installation easier. This feature also influences the construction and reinforcing of load-bearing walls inside the overall structural framework.

Standards and requirements

Aerated concrete wall construction requires reference to STO 501-52-01-2007 and SNiP No. 3.03.01-87. These regulatory documents state that structures composed of autoclaved aerated blocks may only be as tall as five stories, or 20 meters.

Furthermore The following is how the standard determines the strength of aerated concrete blocks:

• for external walls in a 5-story building, blocks with a strength of at least B3.5 and a cement-sand mortar class of at least M100 can be used;
• for walls in a 3-story building – strength not lower than B2.5, mortar class – not lower than M75;
• for walls in a 2-story house – strength minimum B2, mortar class – M50.

External walls cannot be laid using partition blocks. They are just not made to support the weight of a building because they are much thinner.

In order to construct load-bearing walls for a one-story building, the block thickness must be at least 300 mm. Why is this regulation applicable to outbuildings in addition to residential properties?

It is advised to purchase elements with a density of D600 and a strength grade of B3.5 for the construction of basement walls. These products ought to be at least 300–400 mm thick. You can use blocks of slightly lower density D500 with a thickness of 300 mm or more when building non-residential structures.

Since much less of it is required to ensure thermal insulation of a building than the same brick, expanded clay concrete, or wood, the following photo demonstrates how economical aerated concrete is.

What is needed for construction?

Good consumables and tools are just as important for high-quality masonry as good skills and abilities. They can greatly simplify the work of a mason.

Masonry supplies:

• gas blocks of the required thickness, strength and density;
• cement-sand mortar (cement, sand, water, plasticizers, additives);
• adhesive mixture – a special glue that reduces the thickness of the layer between the elements and makes the connection between them stronger;
• reinforcement or reinforcing mesh – to strengthen the wall and increase its strength.

Workplace instruments:

1. A hacksaw or saw with hard teeth – for cutting blocks and giving them the required or non-standard sizes. You can use a wood saw to cut products. Although the quality of cutting will not be very even, this will not affect the performance of the material and its durability.
2. Mallet or rubber hammer – designed for leveling elements and fitting them along one straight line.
3. Drill or mixer with an attachment – for mixing cement-sand mortar or mixing the adhesive mixture with water.
4. Notched trowel and ladle – for applying the solution to products and leveling the mixture over the surface of the blocks.
5. Grater – for combing out protrusions and bumps on individual elements in order to perfectly fit the products.
6. Wall chaser – for cutting special holes or grooves in elements for laying reinforcing bars.
7. Building levels – for aligning elements vertically and horizontally. Both regular and water levels can be used.
8. Tape measure and pencil – for marking blocks with their subsequent trimming.

Because aerated concrete is lightweight and porous, it requires special considerations and techniques when building load-bearing walls in residential buildings. Because these walls are essential to maintaining the building’s structural integrity, strict adherence to masonry standards and building codes is required. Aerated concrete blocks must be handled carefully to avoid damage, wall assembly must be precisely aligned to guarantee stability, and reinforcement must be strategically placed where necessary. By being aware of these characteristics, builders and renovators can guarantee that load-bearing walls in aerated concrete homes are constructed safely, effectively, and to the highest standards of durability.

Instructions for laying external structures

The evenness of the masonry in the following rows will be guaranteed by a properly arranged first row of gas blocks. Furthermore, extra care must be taken when laying out the first row because the foundation or base does not always have a level surface.

Since exterior walls will be exposed to the most rain and snow, it is essential to apply a waterproofing layer on a base that is wider than the foundation before installing the first row.

Otherwise, the lower rows will actively absorb moisture, which will freeze in the winter and then thaw again if you do not take care to consistently protect the foundation from water. Such procedures will ultimately result in the masonry’s initial rows and the building’s total destruction.

Another application for bitumen mastic is waterproofing.

Both inside and outside load-bearing walls Instead of laying the first row on an adhesive mixture, use a cement-sand mortar:

1. Firstly, this can create a flat surface, especially where the height difference is more than 5 mm.
2. Secondly, such a solution will give greater strength to the entire building. The thickness of the cement-sand layer can be within 20 mm.

The block’s outer and inner sides should be coated with the solution; it is preferable to leave the center unfilled to facilitate easy positioning of the element. As there will be air inside, this will also lessen heat loss.

To minimize the thickness of the adjacent layer, one can place successive rows on top of the adhesive mixture (2–3 mm).

External load-bearing wall construction starts at the corner. The order is used to verify that the corner masonry is even throughout the plane. Additionally, a tensioned cord and levels regulate each row that is positioned.

It is necessary to apply the glue using a notched trowel in order to facilitate the later removal of any leftover excess mortar or glue.

The outer and inner load-bearing walls are typically laid in a single block. The frost resistance index in this instance ought to be greater than F35. To construct an external wall, two blocks of masonry can be used. After that, there will be no need to insulate the wall again because the thermal insulation will have increased by two times.

In order to keep external load-bearing walls from cracking, you should place mesh or reinforcing rods every two to three rows.

Problems and errors

There are categories into which all potential issues and mistakes during operation can be grouped. Let’s examine each in more detail.

Violating integrity

The most hazardous since it has the potential to demolish an entire structure. Errors may begin even in the design phase. For instance, if the foundation is laid incorrectly, ground movement may cause the walls to start cracking while the structure is being used.

Thus, a reinforced concrete monolithic foundation is the best choice for aerated concrete walls. The soil needs to be compacted tightly before pouring in the foundation. In order to prevent the foundation from being compromised and its integrity being violated, all tree roots must also be eliminated. Additionally, careful planning must go into the drainage system to prevent drainage water from seeping beneath the foundation and dampening it.

Be sure to install reinforcement every two to three rows when building exterior walls in seismic zones. Nevertheless, thin wire is ineffective because it cannot stop cracks from forming. You need sturdy reinforcement for these reasons.

Reducing building performance

Result in inadequate building insulation, which decreases thermal insulation rather than increasing it. Typically, contractors prefer to seal the gas block and insulate it with brick or pumppan polystyrene foam.

Practice, though, has demonstrated that this kind of insulation has the opposite effect. The building will be colder in ten years than it was without insulation. Additionally, the insulating material will start to gradually delaminate from the inside in a few more decades.

Polystyrene foam combined with an ornamental plaster layer is the best option for insulation. Polyurethane foam must fill all holes in external load-bearing walls.

Additionally, applying a solution or adhesive mixture all over the block’s surface would be a mistake. This is dangerous because it can lead to a heterogeneous structure and the development of plaster layer microcracks. After drying, any leftover excess glue needs to be scraped off with a spatula.

Increased labor and monetary waste

These mistakes result in higher labor and material expenses. The structure is unaffected by these mistakes, but the budget could have a hole in it. As a result, you must select premium materials that are approved and satisfy GOST specifications.

No more than 5% of the total number of products should be comprised of defective or broken elements in any batch. If not, you’ll need to buy a fresh batch of materials and spend money once more.

Pros and cons of aerated concrete blocks

High performance indicators are provided by the aerated concrete block’s composition of the mixture, manufacturing process, and material characteristics.

• Good thermal insulation.
• Dimensional accuracy.
• Fast construction times. Unlike bricks, which are smaller in size, aerated blocks are larger, making them easier and faster to lay.
• The low weight of aerated concrete blocks reduces the load on the base, unlike bricks.
• Aerated blocks are a fireproof material. Therefore, their use as an external or internal load-bearing wall is safe for human life and the integrity of the building.

The drawbacks of an aerated block

1. Due to the porosity of the material, the block can easily absorb moisture from rain and snow. Therefore, it is important to take care of good moisture protection of the wall.
2. In places of high loads, elements can crack, so you need to choose the right wall thickness and ensure its reinforcement.

Load-bearing walls in a home built with aerated concrete require special masonry techniques and close attention to requirements. Preferred for its insulating qualities and light weight, aerated concrete offers benefits but also needs to be taken into account when building walls.

Making sure the mortar is applied correctly and has the right consistency is essential to maintaining the lightweight properties of aerated concrete blocks. By using specialized thin-bed mortar, the foundation’s weight-bearing stresses are reduced and structural integrity is preserved.

Furthermore, when building walls, exact alignment and leveling are essential. Care must be taken when handling aerated concrete blocks to prevent damage and guarantee a tight fit that promotes stability and even load distribution throughout the structure.

Moreover, load-bearing walls are made stronger overall when reinforcement is added where needed. The integration of steel or fiber reinforcement within the mortar joints can strengthen the wall’s ability to bear both vertical and lateral loads, contingent on structural requirements.

Finally, for aerated concrete masonry to maintain its strength and durability over time, proper curing is necessary. For load-bearing walls to have the desired structural performance, proper curing conditions—including moisture retention and temperature control—are essential.

Video on the topic

Construction of a house from Ytong aerated concrete – features of laying aerated concrete blocks