It often happens when, during the reconstruction of a house or during repairs, you have to perform a small redevelopment of the premises. In some cases, this may be prevented by the bearing wall of the building, which cannot be moved or demolished. This problem can be solved by arranging a door or window opening in it. How can this be done correctly so as not to violate the reliability and rigidity of the building?
Before making an opening in the wall, it is necessary to install a special jumper in it. This jumper will have to take on the load from the part of the wall located above the planned opening, from the walls of the upper floors, ceilings resting on the wall or from the roof structure.
As a jumper, it is necessary to choose a material that has sufficient strength and rigidity, since the safety and reliability of not only this wall, but the entire building will depend on it.
When choosing the material of the jumper, its cross section and design, the following factors must be taken into account:
– the dimensions of the planned opening in relation to the area of \u200b\u200bthe entire wall,
– distance from the planned opening to adjacent (perpendicular) walls,
– the distance from the ceiling to the top of the opening,
– the width of the projected opening,
– type and design features of the wall material,
– technical condition and thickness of the wall,
– the number of storeys of the building, especially the number of upper floors,
– location and type of floor slabs.
As you can see, many factors must be taken into account for the design of jumpers, so it is not recommended to take on this work on your own, it is better to seek help from experienced designers. The designer reserves the choice of the type of lintel material, its thickness and design features, and also decides whether it is necessary to install temporary supports to unload the wall (this may be necessary if a very large opening is planned).
In most cases, steel is used as the material of the jumpers. Steel lintels are made relatively quickly and easily. Most often, a channel, corners or I-beams are used for this. At the preparatory stage, steel channels of the required length are prepared, holes for the bolts are drilled in them. The length of the channels should be selected so that they rest on the load-bearing wall, to a depth of 15 – 30 cm on each side. The distance between the bolts should be no more than 50 cm, and the diameter of the bolts should be at least 20 mm. Pay attention to the fact that the extreme bolts should be, in the so-called support zone, above the section of the wall on which the jumper rests. The bolts must be selected in such a way that after installing the channel they protrude by 5 cm, for ease of tightening.
After preparing the jumpers, they proceed to marking the contour on the wall. To do this, through holes are made at the corners of the planned placement of the jumpers to indicate their location on the other side. Further, on both sides of the wall at the place of the planned placement of the jumper, they knock down the plaster and knock out niches for installation with a perforator or a chisel with a hammer. If the wall thickness is less than 24 cm, it is necessary to install the jumpers exclusively in two stages, first on one side and then on the other, so as not to weaken the load-bearing wall. Then mark and drill holes for the mounting bolts. Next, the niche is thoroughly cleaned of dust and brick residues with a wire brush, washed with water. A thick cement mortar (not less than grade M50) is applied to the moistened surface and the channel is pressed into it. The voids between the wall and the channel are carefully filled with cement mortar. The channel is also being installed on the other side. After that, bolts are passed through the holes, washers are placed and nuts are tightened until they stop.
After the solution sets, hardens and gains the necessary strength, you can proceed directly to breaking through the opening. The opening is best punched with a jackhammer or a powerful perforator.
After forming, the openings of the voids of the channel are filled with tiles or pieces of bricks made of cellular concrete. A steel mesh is laid on top, cement mortar is applied and the entire surface of the wall is plastered. If you are making an opening in a load-bearing outer wall, then you need to remember the need for effective insulation of the steel lintel, which can act as a cold bridge. Insulation for multilayer walls is done quite simply – a slab of expanded polystyrene is applied on top and plastered.
If the wall has a single-layer structure, then when installing the jumper, it must be positioned in such a way that a recess of at least 5 cm remains on the outside to accommodate the insulation.
We pay special attention to the fact that if the steel channel will have direct contact with polystyrene foam, it must first be coated with a special anti-corrosion paint to prevent its rapid corrosion. In this case, it is recommended to use a special galvanized style channel instead of a steel channel.
Another option for arranging a lintel above the planned opening is the use of two L-shaped precast concrete lintels. These jumpers do not require tightening with bolts. Preparation of a place for jumpers is carried out in a similar way. A thick layer of high-strength cement mortar (at least M100) is applied to the surface of the cleaned niche and jumpers are installed. After the mortar has completely set, it is necessary to fill all the existing niches between the reinforced concrete beam and the wall with a cement mortar of grade not lower than M50. After drying and setting the solution, they begin to break through the opening. At the final stage, the beam (lintel) is wrapped with a mesh and the entire surface of the wall is plastered.
All door or window opening is ready.
We hope that our advice will help you quickly and efficiently complete the work on arranging openings in the load-bearing wall, while not violating the reliability of the structure of the whole house.