Open up for door in basement

[TuXy]

In my basement, the exterior walls are 30 cm thick and constructed of concrete.

I am considering opening up a small section of an interior wall in the basement to fit in a door.

According to the image below, it is at the arrow where I want to have a door. The wall in question is an old exterior wall of the house, as the house has been extended.
Installing a beam for safety might be a reasonable solution...

Are there any good tips or ideas, or does anyone have something similar at home?

 

[Eld]

What kind of floor structure is above? Concrete? If it's concrete, you can probably just saw, but if it is a wooden floor structure, I would open the ceiling in the basement to check how and where the floor joists are supported first.

 

[TuXy]

It's concrete, however, it seems like there are wooden beams on top of the concrete. But maybe that's how it was done in the past?

 

[TuXy]

About 10 cm of concrete between the basement and the first floor with substantial reinforcement.

 

[Eld]

It's concrete, however, it seems like there are wooden beams on top of the concrete. Maybe that's how they used to do it before?

Yes, they cast a rather uneven concrete slab which was then used to adjust the floor's level. It was a common method.

 

[Eld]

About 10 cm concrete between the basement and the first floor with substantial reinforcement.

If it's like that on both sides of the wall, then just cut the hole. No beam is needed.

 

[TuXy]

Yes, they cast a rather uneven concrete slab on which they then adjusted the floor. It was a common method.

That sounds like a reasonable explanation!

 

[TuXy]

If it is like that on both sides of the wall, then just cut the hole. No beam is needed.

Yes, it is actually like that on both sides.

Do you have any idea how to make a door hole in an economical way?
Normally, hole cutters use wall saws, but if you let a company cut down the wall, it will cost accordingly.. I like to do things myself

 

[Eld]

Saw the contours as far in as you can on both sides with your largest angle grinder. (A 230mm goes in 6-7 cm.) Note, it creates a lot of dust! Then chisel with a rented Hilti.

 

[TuXy]

Saw the contours as far in as you can on both sides with your largest angle grinder. (A 230mm goes 6-7 cm in.) Note, it dusts a lot! Then use a rented Hilti for chiseling.

Will consider a try, because it will certainly dust a lot.. But make sure to wear a good respiratory mask and goggles I'll also check how much it costs to rent a machine with either a vacuum or water to avoid having to clean the whole house.

 

[Fred vom Jupiter]

I had contact with a company about creating a door opening in a former exterior wall, now enclosed in an extension. However, it is still load-bearing.

They wanted to bring in a structural engineer before they dared to make the opening. The engineer suggested removing the plaster above the intended opening so that the masonry becomes visible. Then, a slot should be cut above the door opening with an angle grinder. The slot should extend at least a couple of decimeters beyond the door opening on both sides. One angle of an L-profiled beam is pressed into the sawed slot along with a bit of expansion concrete. Once that has cured, an identical beam is laid from the other side of the wall. Voilà, you have a supportive beam so that you can start cutting and chiseling away the concrete under the beam. Then you can plaster a bit neatly around the beams and the door opening.

Unfortunately, they wanted 32,000 SEK to do the job plus 3,500 SEK for the engineer, after the deduction for ROT, so I backed away from that quote. It felt very expensive.