Close a 7cm thick and 20cm deep groove in a load-bearing wall.

Hello experts,

I am currently facing a challenge. I think this is a question for the masons in this forum.

I had to redo the electrical wiring in a two-family house. After careful analysis, it was noticed that the 4-core 10mm2 cable also needs to be replaced with a 5-core 10mm2 cable. Said and done, and the cable was replaced from the basement up to the first floor. In the process, the walls had to be opened with a slot about 7 cm wide and 2.75 m high. In the 70s, the cable was laid directly in the wall during the building up. Now I have quite large slots in two load-bearing walls in two apartments that obviously have to be closed again. Here I am asking for the statements of the experts among you. How do I restore the maximum stability of these walls? Has the wall been significantly weakened by the slots at all, since they are vertical slots? There are also now a bunch of cables in the wall: 2 main lines and 6 Nym 2.5mm2 cables. Do these interfere with closing the slot?

As a "layman," I would now have proceeded to close the slot gradually from bottom to top with expansive mortar. Expansive mortar to apply a little pressure to the whole thing. Or is that rather counterproductive?

It would be nice to get a little digital support from you.

Thanks in advance and best regards Sebastian

You really made 20cm deep slots in a load-bearing wall? So almost through the entire depth of the wall?

Hello Nordanney,

yes, I had to. Otherwise, I wouldn't have gotten to the cable. I didn't want to open the stairwell and therefore went from the apartment into the wall. I also didn't expect the cable to be almost in the stairwell. Actually, only the plaster from the stairwell is holding the wall together. Can you give me good tips on how I should proceed now?

Best regards, Sebastian

Can you give me good tips on how I should proceed now?

Sorry, since in load-bearing walls a maximum depth of 30mm is allowed for chasing (at this depth you could have gone 20cm wide, provided the wall is at least 30cm thick), now the only option is to consult a structural engineer. Possibly even further structural measures may need to be taken.

I am currently facing a challenge.

Uh, no, behind. If I understand correctly, you have chased out a cable from the opposite wall side. With such a careless approach, I probably don't need to suggest that you illustrate your thread with layout drawings. But maybe with photos?

Why didn’t you just make a new cut and not such a deep one!! Personally, I would have left the old cables in! Now the game is up