- General technology
- Wall material
- Openings in interior partitions
- Openings in load-bearing walls
- Strengthening the opening
The load-bearing wall seems to be an insurmountable obstacle, but modern technical means make it quite easy to make an opening for a door or window. We will talk about the technology of forming openings using a hand tool and the rules for strengthening it..
Making an opening is a responsible technological operation associated with the risk of destruction of building structures and danger to life and health. Therefore, all work should be performed in strict accordance with the regulations. The process of cutting the opening itself consists of three stages:
- Marking, and if necessary – coordination and approval of the reconstruction plan.
- Directly dismantling of a part of the building structure.
- Reinforcement of the opening when it comes to working with a capital wall.
A professional approach implies the use of special wall-sawing equipment, however, you can make the opening yourself, using only a hand tool: a perforator, angle grinder and additional equipment for them, it is also desirable to have a construction vacuum cleaner. The complexity of the process will be higher, but with the right approach, you can achieve a neat design of the perimeter, subsequently spending a minimum of effort on finishing.
The main difficulty of working with a hand tool is the impossibility of making a cut line in one technological operation. The cutting depth of angle grinder is 60–80 mm, therefore, to make an opening in the interior partition, at least trimming is required on both sides. If we are talking about a main wall, it is necessary to make a stepwise excavation of the material, each time developing a wide groove for access of the power tool to the cutting zone. When a through cut is made along the perimeter of the opening, the core is cut down, fragmented and removed in pieces weighing 10-15 kg.
There is a huge difference in what material the wall is made of. When cutting and crushing, brick, concrete and gas silicate behave differently, this must be taken into account when dismantling.
If you have to deal with aerated concrete, the impact method of destruction is not very good, with the help of a perforator you can only make a chaotic system of holes. It would be much more correct to make a large hole in the corners of the opening, and then cut along the marking line with an ordinary hacksaw or tape blade for aerated concrete.
The brick splits well, so the best way to work is to cut the groove along the contour of the opening, followed by crushing the core. In a similar way, it is better to do with thin-walled hollow materials like cinder block: a preliminary cut will make it easy to refine the opening after making the passage.
The most difficult to make an opening in monolithic concrete walls. For apartment partitions up to 100 mm thick, the best way is contour cutting with a diamond disc along the aligned markings on both sides. Cutting is carried out “on the run” to form technological gaps, allowing free extraction of the core. The main problem is the reinforcement, for cutting of which the gap can be extended to 80–100 mm. It is worth noting that cutting openings in structural concrete of strength class B30 and higher can only be performed with special wall-sawing equipment, the impact method of dismantling in such cases is prohibited.
Openings in interior partitions
Partitions up to 100–150 mm thick are easier to cut, but careful alignment of the markings is required, because cutting is carried out from both sides. To align the markings, two control points are enough – the upper corners of the opening, in which through holes are drilled. When working, you need to carefully monitor the perpendicular position of the drill.
The control points must be connected with a horizontal line, and also two vertical lines on both sides must be discarded using a plumb line. Then, with an indent of 15–20 mm, cut lines are drawn in both directions from the contour marking. In the room where it is planned to excavate and disassemble the core, the marking should have an indent of 10-15 mm more to form a wedge-shaped gap.
Along the outer marking lines, a cut is made with a grinder to the entire effective depth of the disc. You can chop the core of the groove with a chisel and even manually, driving it into one of the cuts. To select material from the groove, we recommend crushing it by drilling 20–24 mm holes in the central part of the cut with a step of 10–15 cm – such fragments can be easily removed with a hammer.
Openings in load-bearing walls
Difficulties in working with capital structures mainly lie in their considerable thickness: even with a two-sided approach, overlapping of the sections is not ensured. Therefore, there are only two options for making an opening in a load-bearing wall: contour drilling and stepped trimming..
It is reasonable to drill the opening around the perimeter when the wall thickness is over 250 mm, when the cutting method becomes irrelevant due to the large number of steps. For contour drilling, it is necessary to temporarily attach two 40×40 mm bars to the wall, the gap between which is the same along the entire length and is 14–18 mm. With a drill of the same diameter, it is necessary to drill with a step of 20–30 mm, keeping the tool strictly horizontal. Next, drilling is performed at an angle of 30–45 ° to weaken the walls between the holes. For the same purpose, you can pre-expand the holes with a larger diameter drill..
The remaining ties are removed with a perforator – percussion work in order to clear the cut is allowed even in structural concrete, but reinforcement cannot be chopped in this way. It must be cleaned of concrete and eaten using a bolt cutter, or sawed with a hacksaw. Before the reinforcement ties are cut, it makes sense to divide the core with several drilling lines to make dismantling easier..
Important! Unlike a professional one, a household tool is not intended for continuous continuous work, it needs to be given rest in accordance with the set duration.
Strengthening the opening
Please note that the manufacture of openings in the load-bearing walls of apartment buildings is allowed, but only subject to agreement on the reconstruction and approval of the project to comply with technical conditions. One of the mandatory requirements in such cases is to strengthen the opening to restore the bearing capacity of critical structures. And although it is not necessary to develop a project for the reconstruction of a private house, strengthening should still be carried out.
It is made with angle steel, the shelf width of which is at least 1/4 of the wall thickness. The upper bar is inserted into the cut previously made. Along the plane of the wall, sections of a steel strip are welded to it, which are fastened with a through or anchor fastening to the pillar of the wall at least 20 cm from the top of the opening. The length of the horizontal lintel must be at least one third greater than the width of the passage made from each side. Once the top bar has been installed, vertical cuts can be made and the core removed. After that, the corners of the lintel are fastened together by inserts from a steel strip, butt-welded to the corner. In the same way, the side faces are strengthened by setting the corners to the support of the lintel.
In some cases, when the dimensions of the opening exceed normal, as happens when two rooms are combined, it is reinforced not with rolling materials, but with frame structures and trusses. After that, the reinforcement system is sheathed with plasterboard, due to which it is possible to completely hide the metal structures without disturbing the interior.