How to expand a doorway for a metal door

Recommendation points

• What walls are we dealing with
• Determination of the position of the jumper and its strengthening
• Dismantling surplus
• Processing the edges of the opening

Quite often, the installation of heavy doors requires the expansion of the opening, which is done according to special rules. It is necessary not only to ensure the correct geometry and respect the dimensions, but also not to violate the integrity of the supporting structure, so that over time the reliability of the installation is not compromised..

What walls are we dealing with

Usually a metal door is installed as an entrance door, which implies work to increase the opening in the load-bearing wall. On the one hand, this requires coordination with the services of architectural or housing supervision, on the other hand, it becomes necessary to apply a number of engineering solutions aimed at restoring the strength of building structures.

Expansion of the opening cannot be performed without prior agreement. But here, too, a number of reservations can be made: for example, if the expansion involves the removal of material along vertical edges within the tolerances according to GOST, this operation can be attributed to ensuring the mounting gap. In fact, the expansion of the opening on such a small scale affects only the protective layer of concrete, and for brick and block walls it is not at all critical. Therefore, thin trimming can be done independently, all the same, the actual width of the doorway will remain the same and the fact of violation will be almost impossible to establish.

Another thing is if an opening is required, which implies a weakening of the bearing capacity of the wall. The possibility of such a reorganization in the communal sector should be agreed with the local city administration by submitting an application through the MFC, and for houses with high architectural value – in a special executive body, in Russia called Rosokhrankultura. In Moscow and St. Petersburg, such approvals are carried out in the city departments of the housing stock. Approval can be issued only if there is a redevelopment project, for the preparation of which you will need technical data on the building (copy of the passport), as well as the consent of the drafter of the series of the house or research institute in which this project was developed. A separate part of the reconstruction project is a set of measures aimed at maintaining the original bearing capacity.

For walls that do not experience additional stress, the situation is different. In the absence of a bearing capacity, it must be increased, at least to be able to secure a massive block of a metal door. As a rule, this is provided by a simple laying of side columns or embeddings, while the opening in the main wall is reinforced with supporting metal structures and concrete.

Determination of the position of the jumper and its strengthening

Above openings in walls of almost all types, a reinforcing lintel or crown is installed – a monolithic product, the task of which is to distribute the mass of the wall and structures over the opening along its edges. An exception to this rule is made of monolithic concrete walls, where the lintel is made in the form of a reinforced belt of reinforcement, which is why the project for expanding such an opening vertically almost never passes approval..

In other cases, the situation remains rather complicated. In the case of vertical expansion, it may be necessary to remove part of the lintel, which will reduce its rigidity. When the opening widens to the sides, the support plane decreases and the concentration of the load increases. The final decision to restore strength depends on the designer of the conversion project, but, as we already know, such a project is not always required..

For non-capital walls, the following activities can be proposed:

1. Installation of the door in a rigid metal box, the deformation of which is limited by anchoring to the wall.
2. Strengthening the edges of the opening with a metal channel
3. Installation of lintels reinforcing the lintel in the form of two steel plates on opposite sides of the wall with a rigid mechanical connection.

The final decision should be made depending on the degree of intervention. So, if the lintel is completely dismantled or, due to the expansion of the opening to the sides, it loses more than half of the bearing area, it will have to be mounted again. For this, the section of the wall above the door is unloaded, a new reinforcing element made of steel or concrete is installed and it is sealed in accordance with the requirements of SNiP.

Marking, installation clearances and tolerances

When everything is ready to expand the opening, it is necessary to determine the dismantling zone. It is equal to the actual dimensions of the assembled door block, to which the gaps from the edges of the opening necessary for a high-quality technological installation are added. The problem is that the values ​​of these clearances are not precisely defined by any of the building codes. And although they should be indicated in the technical specifications for the production of products, this documentation provides only general recommendations..

Let’s try to figure it out on our own: the gap between the door frame and the opening has three functions: assembly, compensation and insulation. From the point of view of installation, everything is quite simple: the gaps should allow free turning of the door in the opening for its positioning, that is, the door in any position must move freely inside the opening, which means that its dimensions must correspond to the largest dimensions of the door block. You can’t go wrong if, to ensure sufficient mounting clearance, define a box into which you can fit the complete door unit, and take the distance between its diagonally opposite edges as a reference.

With the compensation function, everything is more complicated, the gap from this point of view is determined not so much by the door itself as by the characteristics of the building structure. So, for wooden houses, shrinkage manifestations are more pronounced, as in structures built in seismically active regions. It is better to consult the drafters of the construction project on this matter..

Well, the function of insulation: it all depends on the requirements for the material with which the gap is filled. For example, for foam joints it is recommended to provide a gap width of at least 15–20 mm, for tape seals made of felt and rubber – at least 30 mm. It is safe to say that in most cases the mounting clearances are large enough to accommodate virtually all types of aggregates. However, do not forget that often the opening has to be prepared: plastering or mounting the cover. Thus, the minimum thickness of the materials used to prepare the opening should be added to the dimensions of the opening..

According to the dimensions obtained, markings should be applied to the walls on both sides. The lines delineating the degree of removal of excess material should, if possible, be located symmetrically relative to the axis of the existing opening. However, in some cases, a shift of the opening may be required, for example, to ensure the desired opening angle of the canvas, the presence of furniture or communications on adjacent sections of the walls. Before deciding on the displacement of the opening, it is recommended that you familiarize yourself with GOST 30971-2002 for door installation.

Dismantling surplus

Removal of material to expand the opening can be done by shock and non-shock methods. The availability of a particular method is determined by the requirements for the operation of a certain type of building, for example, the impact method of dismantling concrete and brick walls is prohibited in apartment buildings, the operation of which continues. In any case, the impact force is limited, which allows the use of only household tools, the performance of which may not be large enough.

When widening the opening in walls with a thickness of more than 100 mm and a distance of more than 100 mm in each direction, diamond or wire cutting is recommended. This is a quiet method of dismantling, in which dust and small debris are practically not formed. Modern equipment, with which the construction industry is now quite well-saturated, allows work to be completed within one day, including the installation of the door itself and cleaning. The cost of this kind of services is quite democratic: on average, for cutting 1 lm. you will have to pay 1000 rubles for every 10 cm of wall thickness, that is, about 5 thousand rubles for the opening.

You can also remove excess material with your own hands, for example, by drilling a number of holes along the fracture line with a frequency of 50–70 mm. Removal of the layer can be carried out with partial trimming and further breaking into small fragments, or the separation of the whole block by the force of a jack. The easiest way is to work with thin walls: with a thickness of up to 80 mm, an ordinary angle grinder with a stone circle will cope with the task, you just need to accurately calculate and compare the cutting lines. In some cases, it makes sense to resort to stepped pruning.

Processing the edges of the opening

An additional advantage of mechanized diamond and wire sawing is the absolutely flat and smooth edges of the finished opening. In such cases, it is enough to apply a dense layer of primer, after which you can immediately proceed with the installation of the door block.

After self-expansion, the edge of the opening remains torn and it must be smoothed with a tolerance for irregularities of the order of 1 cm / lm. For almost all openings in stone walls, the plastering method is applicable. Wide boards are attached to the walls, the edges of which are set exactly in the plane of the future opening, taking into account all the necessary gaps, after which such a vertical formwork is filled with cement mortar of the M400 brand with the addition of setting accelerators. This method of preparation is also often used when expanding the openings of concrete walls, even with diamond cutting, this is necessary to restore the protective layer of reinforced concrete.

In frame and timber houses, the wet preparation method is not used. In such cases, panel materials are used to refine the edges of the opening: boards, OSB strips or metal sheets. This method of preparation is good for its high speed and convenience in performing work: a relatively light cover is assembled on the floor in a convenient place, and then fixed in the opening using dowels or anchors.

Special recommendations can be given for openings made in walls made of loose materials: aerated concrete, slag-cast, cellular. During the preparation of the opening, it is often required to sample niches for the installation of embedded elements that strengthen the fastening of the door frame. If such a need is provided for by the conversion project, during the dismantling stage, additional material extraction should be carried out, and then the space should be filled with concrete or other dense incompressible material..