How to lay out walls from gas silicate blocks

Recommendation points

Gas silicate blocks (aerated concrete blocks) today, as a material, are the most popular in construction due to the following obvious advantages: low thermal conductivity, relatively low specific weight, ease of installation and processing. They do not require additional preparation for finishing. Those. you can plaster both outside and inside directly along the block, without using any additional materials, while excluding additional costs.

To lay blocks, you will need the following tools: a trowel-spatula with teeth (it is better to choose a tooth size within 4-5 mm), a rubber hammer, a mixer-drill with a nozzle for stirring glue, a block saw, a level.


The first thing to start with is the marking of future walls. It is necessary to choose the main 4 corners of the future house and mark them, be sure to check the equality of the diagonals. A prerequisite is that the blocks protrude at least 5 cm relative to the foundation or basement, a common mistake is laying blocks in the same plane with the foundation. This is done in order to exclude the ingress and seepage of moisture, which, flowing down from the walls, falls directly onto the joint between the wall and the foundation. To pull the thread in the corners (it is better to take a thin silk thread), you can use wooden bars with nails driven into them, driving them well into the ground to a depth of 20-30 cm. It is better to finally align in the corners with two spacers for each bar, gradually “pulling »Them to the desired thread position.

Block masonry

After the marking is done, they begin to lay the first row of blocks. Be sure to use a reinforced roofing felt as waterproofing, which must be folded in half. It fits directly under the first row of blocks. After laying the roofing material along the entire perimeter of the marked walls, proceed to laying the blocks. The mortar is mixed in the following ratio: cement / sown sand, as 1: 4. The solution must be practically dry (it is important not to float), otherwise you will not be able to align the block, because it will constantly sag under its weight on a “soft” solution. For each block, make two “tracks” from the solution along each edge of the block, about 5 cm high – this is optimal for leveling the block.

Gas silicate block laying
When applying the mortar, leave an “air line” between the adhesive beads. This method is an excellent additional thermal insulation for the walls of the house..

With light blows of a rubber hammer, set the block in a horizontal plane. Initially, you need to set 4 supporting corner blocks – this is the most time-consuming process that requires attention and diligence. The “curvature” of your future walls depends on the installation of these four blocks by 50%. Further, by pulling the thread between the support blocks, all in-line blocks can be laid on the mortar, and between themselves they are lubricated with a special glue for gas silicate blocks. As for the choice of glue, I advise the very well-proven glue “Zabudova”, it has the best price / quality ratio, besides, its thermal insulation properties are at a high level. To cut blocks, you must use a hacksaw on gas silicate blocks with victorious tips. There are two types of hacksaws by teeth: saws with victorious tips “for each tooth” and “through the tooth”. In terms of price, they differ by 10-15%, but in terms of ease of operation and quality of sawing, the first is much better, moreover, it is much more convenient for it to saw. The most optimal option in terms of price / quality today is a Vorel saw. The building level is used no longer than 80 cm, since the size of an ordinary wall block is 625 (600) mm by 400 mm. Check the horizontal plane of the block as follows: putting the level on the diagonal of the block in two positions; and to level the wall – along a tight thread. The glue is diluted with water and stirred with a mixer until it resembles sour cream in consistency. Apply the adhesive in two strips along the edges of the block using a 15 cm notched trowel. In the center there should be a small strip without glue. With this method of application, it will be more convenient to level the block in level, and the air gap between the blocks will improve the thermal performance of the wall, because the “bottleneck” of heat loss through the walls is just the glue seams. It is preferable to wet the blocks with water in the places of subsequent application of glue, because the gas silicate block absorbs moisture very well. And if the glue is applied to a dry block, it dries immediately, which negatively affects the characteristics of the bond between glue.

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The block is immediately aligned in the horizontal plane, and after that with 2-3 blows to the end of the block, it is pressed against the previous row of blocks.

Gas silicate blocks
Apply light force when hitting the block – blocks crumble easily.

When laying the second and subsequent rows of blocks, it is imperative to use block binding, i.e. the next row should go with a block offset of at least 15-20 cm relative to the previous one. You also need to monitor the dressing at the joints of the bearing walls..

Gas silicate blocks
Roofing material is laid along the perimeter of the entire house under the first row. It is important that the edge of the roofing material protrudes 10-15 centimeters, as shown in the photo. Also make an allowance of 10 cm between the sheets of roofing material..

Places of window and door openings

Window openings start at the level of the fourth row (at a height of 100 cm). Subsequently (taking into account the screed and insulation on the floor), the window height will be about 80 – 85 cm. The upper level of window openings is at the level of 10 or 11 rows, depending on the height of the ceiling. But the distance from the opening to the ceiling should not exceed 35 cm (however, these are not building codes, but more aesthetic ones). Doorways should end at the level of the 9th row, which corresponds to a height of 225 cm. After filling the subfloors and laying the insulation, the height of the openings will be 210-215 cm. Lintels must be installed above all openings. There are two main methods for doing this. The first, the simplest, is the installation of a ready-made prefabricated reinforced concrete bulkhead. But there are pitfalls here, there are several of them. Firstly, reinforced concrete has a very high thermal conductivity, as a result of which such a bulkhead will freeze in winter, and the consequences and conclusions of this are obvious. Therefore, additional work and costs for thermal insulation of such a bulkhead will be required here. Secondly, sometimes it is very difficult to find a lintel of your exact size under the opening, both in length and in width. Thirdly, the cost of factory products and delivery to the construction site eventually adds up to a large amount. The best option is to make a monolithic lintel on your own. In terms of labor costs, this method even wins over the previous one. To do this, start by installing spacers under the future jumper, and they can be nailed to the blocks with ordinary nails (120 m or 150 m).

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How to lay out walls from gas silicate blocks
It is imperative to reinforce the monolithic lintel from below, as shown in the photo. Hold the fastening for at least a month.

It is important to set the guides strictly according to the level of the previous row of blocks. Next, prepare the fixed formwork for the future lintel, in this case, these will be blocks with sawn out hollows. The width and height of the hollow should be 20 by 15 cm, respectively. It is necessary to saw out with a slight extension towards the base of the block (this is done to prevent the block from slipping out of the monolithic jumper itself). Then the finished tray blocks, obtained in this way, are installed on spacers, as elsewhere, smearing the blocks with glue. An important point is that the trough block must go at least 20 cm onto the bearing wall. This will exclude the formation of cracks and chips in the wall, as well as subsidence of the lintel..

How to lay out walls from gas silicate blocks
Top view of a self-made lintel.

Concrete of grade M200 and higher is poured into the finished tray (composition ratio of crushed stone / sand / cement 3: 1.5: 1). At the very end, reinforcement (2-3 pieces with a diameter of 10 mm or 12 mm) is laid in concrete as low as possible to the base of the block, because the breaking load is maximal precisely in the lower part. It is necessary to withstand the lintels poured in this way for a month, but this does not mean that the laying of blocks cannot be continued. During the month, the load on the lintels associated with the laying of floor slabs, the installation of columns, girders is not allowed.

Monolithic belt

After laying the last row of blocks, a monolithic belt of reinforced concrete must be poured without fail. With a block thickness of 400-500 mm (and a smaller thickness is not allowed according to SNiPs for thermal insulation), the dimensions of the belt must be at least 20 x 15 cm. It is not allowed to fill the belt over the entire width of the block, thermal insulation must be organized. There are two most optimal ways: 1) use the gas silicate block itself as a heat insulator, 2) use penoplex or expanded polystyrene as a heat insulator (in everyday life – foam). The first method is more practical due to the fact that gas silicate is an order of magnitude stronger than polystyrene and polystyrene foam, and when using it, there is no need to install the formwork, because the blocks themselves will be a kind of permanent formwork.

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Consider the first case: Two types of pieces are sawn from blocks: the first 15 x 15 cm, the second 5 x 15 cm (with a belt height of 15 cm). It is done as follows: from the side of the street, lay pieces of 15 x 15 cm, and from the side of the future room – 5 x 15 cm. The result is a hollow with dimensions of 20 x 15 cm. In this state, the glue should be allowed to dry for 2-3 days in order to avoid bursting of the blocks during the pouring of concrete. This type of permanent formwork must be done on all load-bearing walls..

After 2-3 days, you begin to lay the reinforcement around the entire perimeter of the belt. It is enough to lay reinforcement with a diameter of 8-12 mm in two rows. Pour concrete of a brand of at least 200M (the ratio of proportions has already been described above) and pour it around the entire perimeter. It is very important to make the belt within one day, because hardening of concrete is not allowed due to the fact that cracks may appear at the joints over time due to load.

Further on this belt, you can lay floor slabs, or use another method of floor overlap. In the same way, a monolithic belt is made around the entire perimeter and under the roof.


Partitions inside the house are made, as a rule, from blocks with a thickness of 100-200 mm, depending on the purpose of the premises, as well as the desired heat and sound insulation parameters and requirements. There is no need to make a monolithic belt for such walls, since they are not subjected to heavy loads like load-bearing ones. It is imperative that they be tied up with load-bearing walls. For this purpose, pieces of reinforcement are usually used, about 20-25 cm long, which are driven into the load-bearing wall half of their length. Then the place of entry of the reinforcement into the block is outlined, which will subsequently be docked with the load-bearing wall. A hole is drilled in the block for the reinforcement by 2-3 cm longer than its length to prevent splitting, and the block is pushed onto the reinforcement, all joints are pre-coated with glue. Here you also need to remember to use a bandage between the rows. Regular building foam can be used to tie up partitions with ceiling slabs. It is advisable to foam it over the entire width of the wall, passing first from one side of the wall, and then from the other. After the foam dries, it is trimmed to the level of the wall with an ordinary office knife. The gap between the block and the ceiling should be no more than 1-2 cm due to the weak compression / break properties of the foam. Otherwise, the method of laying partition walls is identical to laying blocks in load-bearing walls..

Partitions from blocks
The load-bearing partition is made of wall blocks, since the load of the floor slabs will be distributed on it.

In general, by observing all of the above technologies and norms for laying gas silicate blocks, you can avoid common mistakes that inexperienced house builders encounter when erecting walls..

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