How to cut a window in an aircrete wall

The main difference from other wall materials is the presence of porous structure and weak self-supporting capacity. Mortgaged plastic and wooden windows need to be fixed by special expanding dowels (conventional ones are unsuitable because of the risk of tearing out), GOST provides for vapor and water barriers between the frame and the blocks themselves, excluding direct contact of the external environment with the package. Preventive measures include the reinforcement of the opening at the stage of construction of the walls. This is done by laying an aerated concrete lintel or closed insulated metal corner, with a large area and the weight of the fixed structure to be strengthened not only the upper part, but also the side edges.

To avoid the risk of accumulation in the joints of condensation all joints are made as hermetically sealed, subsequently the joints are recommended to close the pieces of aerated concrete, a thick layer of plaster or special PVC trim. Long dowels or anchor plates fixed with screwed-in self-drilling screws (not less than 3 pcs per 2 m of length) provide mechanical fixation of the packet. Silicone bonding tape and/or a layer of foam with a small pore diameter and low expansion properties act as insulation. Optimal results are achieved by laying a three-layered mounting seam.

Installation of plastic windows is carried out after processing sections of the opening with antiseptic and adhesion-increasing primers. This procedure closes the cells of the blocks and reduces the influence of dust on the quality of adhesion of sealing tape and foam with the surface. All materials used in the arrangement of the joint, should have a long service life (20 years and above), saving in these areas is unacceptable. The same applies to plates and screws with the most reliable anti-corrosion protection.

How to make window openings in cellular concrete?

Recently I was asked a question, How to do windows and window lintels in the walls of aerated concrete blocks?

Aerated concrete block is very easy to saw with a special saw on aerated concrete.

With the help of a special angle, the cut is perfectly flat and therefore it is always easy to bring the block to the window opening of the right size.

The only condition is that the cut block must be not less than 12-15 cm to be inserted from the edge. in length.

The height of the window opening can also be regulated by trimming the block, or the selection of blocks of different heights, for example 200 and 250 mm. But it will be impossible to implement, if you have not procured in advance blocks of different nomenclature and size or you do not have the ability to bring them quickly.

A more complicated point is the installation of the window lintel. There are several variants. Both installing precast concrete window lintels, concreting with reinforcing lintels in place of the window, and installing wood or metal window lintels. But all these options have several significant drawbacks.

1-Concrete lintels or monolithic concrete have a much higher coefficient of thermal conductivity compared to aerated concrete, and to solve the problem of freezing the wall above the window, you must lay a layer of polystyrene insulator. Thus, we get a multi-layered pie of aerated concrete, polystyrene and concrete, quite time-consuming and requiring high quality performance. And you must remember that if the width of the window is more than 2.5 meters height of the monolithic concrete window lintel should be at least 40 cm to meet the requirements of SNIP for strength properties.

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Therefore, such lintels are appropriate only for large windows, more than 2 meters wide.

2- The consequence of the insertion of insulation will be a weakening of the structure and the loss of water vapor permeability. Although the safety factor of the concrete is enough to keep the whole wall with 15 cm of monolith, but the vapor barrier will definitely lead to condensate accumulation on the inside of the window opening and a possible occurrence of blackened mold.

The option of wooden lintels in the openings, I do not want to consider and do not advise, as the most unreliable.

The simplest and most reliable, tested in practice, is the variant of installation of gas concrete on lintels of the metal angle.

True, the installation of the corner must be done in a certain way. Under no circumstances should you put a corner on the outer and inner side of the block, and only cut it into the body, giving 1/3 of the width from the edge.

Depending on the width of the opening, i.e. the lintel length, up to 1.2 m can be used., or 75th angle up to 2 meters.

Let me explain about the strength properties. The strength of the angle is enough to withstand a row installed on it and planted on the adhesive gas silicate blocks.

Continued laying of gas concrete blocks on the glue with banding, provides high strength wall masonry after its hardening. The tests carried out by us in the factory proved that the strength of the glue joint between the gas concrete blocks is much higher than the strength of the block itself, so there is reason to believe that the gas concrete blocks laid in the wall masonry on the glue for gas concrete, after hardening is a monolithic gas concrete structure with strength characteristics not lower than those declared by the manufacturer of the gas concrete block.

window, aircrete, wall

Thus, by installing lintels from metal angle, we eliminated the drawbacks of concrete lintels and maintained the thermal properties of the wall above the window opening, avoiding the possible appearance of moisture on the window jambs.

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Depth of support

For the reliability of the entire structure it is very important to correctly calculate such parameters as the area of support, length and width of the reinforcing products. These components are determined based on the width of the window opening, as well as the height of the masonry above it. Depending on the type of lintel footing depth on the aerated concrete wall or the minimum length of the institution in the masonry. The most popular options are:

  • Reinforced product made of high-strength cellular concrete with an opening length of up to 174 cm. If the device is used for a supporting structure, then the minimum value of the support is 25 cm.
  • Reinforced concrete product. For window openings up to 300 cm wide, a U-shaped lintel will be inserted into the masonry at 25 cm, whereas a monolithic structure for openings up to 200 cm will be inserted at 35 cm. The second option, unlike the first, requires additional external insulation.
  • From metal elements. For window opening widths up to 200 cm, 20 cm into the masonry. Must be sunk into the wall.

The option without lintels is also used in practice. For the realization of the conceived it is necessary to observe a few requirements:

  • The width of the window opening does not exceed 120 cm.
  • The height of the masonry above the frame is no more than 2/3 of the opening width.
  • Temporary formwork is arranged.
  • Several rows of reinforcement are carried out over the reinforcement.
  • The voids are filled with aerated concrete glue.
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window, aircrete, wall

Depth of support

For the reliability of the entire structure it is very important to correctly calculate such parameters as the area of support, length and width of reinforcing products. These components are determined on the basis of the width of the window opening and the height of the masonry above it. The depth of support of lintels on the aerated concrete wall or the minimum length of the installation in the masonry are determined depending on their type. The most popular options are:

  • Reinforced product of high-strength aerated concrete for an opening length of up to 174 cm. If the fixture is used for a supporting structure, then the minimum support value is 25 cm.
  • Reinforced concrete products. For window openings up to 300 cm wide, a U-shaped lintel must be inserted 25 cm into the masonry, or 35 cm into the monolithic structure for openings up to 200 cm. The second variant, unlike the first, requires additional external insulation.
  • From metal elements. Up to 200 cm window opening width: 20 cm into the masonry. Must be anchored into the wall.

The variant without jumpers is also used in practice. To implement the conceived, it is necessary to comply with several requirements:

  • The width of the window aperture should not exceed 120 cm.
  • The height of the masonry above the box is no more than 2/3 the width of the opening.
  • Temporary formwork is arranged.
  • Several rows of reinforcement are built over the reinforcement.
  • The voids are filled with aircrete glue.

Step by step installation of windows in an aerated concrete house with your own hands

Aerated concrete is now an increasingly popular material. It is even used to erect residential buildings. Aerated concrete not only has sufficient strength, but also has a number of advantages. low weight, good thermal insulation properties and so on. This explains its growing popularity. If you have decided to build a house from aerated concrete, then one of the important stages of the construction work will be the installation of windows. It is quite possible to do this with your own hands. However, in this case you can’t do without an assistant. It is not easy to operate a rather heavy window alone.

What causes the deformation of the walls?

Strong shrinkage does not give the material from which the walls are made, but the incorrect distribution of pressure on the soil. If the ground rises or falls, changes its structure due to the fact that it contains a lot of groundwater, there is a risk of shrinkage of the building. It can occur either immediately or several years after the building has been erected.

To protect the building from this you can, properly equipping the foundation. If you are building on unstable soil, the base of the building should be well reinforced, have waterproofing and gutters, diverting water to the side. Only the proper preparation of the foundation can protect the building from moisture and shrinkage.

After installing windows, first of all, you need to take care of the lining. Read our article “Exterior slopes for plastic windows: types and peculiarities of choice”. Instructions for creating a slope of PVC panels with your own hands are in our material at

How to install windows in a wooden house is described in the article “Installing windows and doors with jambs in a wooden house yourself”.

Installing the fasteners on the frame

Remember that the use of plates does not give the possibility to strengthen the window in the aperture area with the same reliability as it would be with the use of anchors. But when the method with plates is chosen, it is not recommended to use hanging elements for gypsum plasterboard sheets. It is better to use special window plates which have good rigidity.

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Making an AIRCRETE Garden Wall & Height Test

The elements are fixed to the frame with screws, their long ends must point inward. Before installing a window in a gas concrete wall, it will be necessary to knock down a certain part of the plaster layer from the slopes to fix the plates exactly to the walls. This is the only option which ensures a secure installation.

When fixing the fasteners to the frame, follow the following recommendations:

  • The plates are fastened with a spacing of not more than sixty centimeters;
  • each window construction has imposts, located horizontally or vertically and giving the frame rigidity. From such a connection, the plate is attached at a distance of twelve to eighteen centimeters;
  • The same distance should be set back to fix the plates at the corners of the frame structure.

perfect window cutting with cutter machine��

Counting is done from the inner corners. Fix it with screws, the size of which is 4 by 19 mm.

If it is decided to use anchors to mount the window in the gas block, then the frame is pre-installed holes. when choosing the distances between the fixing elements, use the recommendations given above.

It is necessary to understand that in the matter of correct installation of the window (anchor or plate) there is no unambiguous answer. With the help of plates the process will go faster, but during operation the block may shift a little, there will be a warp, the operational period of the entire structure will be reduced.

Metal corners for lintels and their installation

Lintels of metal angle can be made of different sizes, using a saw for sawing aerated concrete. Due to the variety of sizes and the possibility of easy sawing of the block, choose the height of the windows. Metal lintels do not transmit heat, so they need to be insulated by qualified specialists.

To install the aerated concrete block on the lintels, metal corners are placed in the middle of the aerated concrete block at a distance of one-third from the edge. The advantages of metal lintels are strength and the ability to hold honeycomb blocks of a mixture of lime, sand and water. Construction with the use of metal corners from the outside looks neater due to the resulting flat surface. The thickness, height of metal lintels depends on the size of the supporting structure, and there are the following types:

  • metal beams or bent profiles;
  • I-beams;
  • metal profile pipes;
  • hot rolled steel angles.

For convenience, when installing aerated concrete use not two metal brackets, but four. Thereby providing greater support, which is especially important in places with frequent earthquakes. The process of installing a metal lintel consists of: reinforcing, selecting the height, mounting and propping the formwork, as well as tying and concreting the reinforcement.

Preparing the opening for installation

This work should be carried out as soon as the opening has been made. After laying the wall, it is always difficult to cut an opening for the door unit. Its dimensions should be slightly higher and wider than the structure planned for installation. To accurately mark the opening and arrange the cuts will be required:

In order to strengthen the top of the cut ten-inch slots in the side walls, reinforcing bars are inserted, expanded and fixed with wedges. During finishing work, the hollow areas are filled with quick-hardening mortars.

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