Hello
My plan is to create an opening for a door in a load-bearing wall. The wall is between the house and the garage (in the basement). The garage was added to the house at a later time. The wall is made of concrete hollow blocks, approximately 25 cm thick. The house is 1 story with a basement. The door opening will be perpendicular to the roof trusses and the intermediate floor. The house has a gable roof with concrete tiles. From the floor inside the house up to the underside of the sill (?) in the intermediate floor, it is about 2110 cm. An extension also rests against this wall. See drawing:
Question 1: Is it feasible to install a door with the module dimension 9x20? That is, with a beam that is 100 mm high.
Question 2: To satisfy the requirements of the municipal officials regarding a strength calculation for building notification—is it possible to calculate in reverse, that is, compare the existing wall's load capacity and replace it with a beam that can handle as much? I don't feel like spending 5000 -10000 for a calculation.
Question 3: Since the garage was added later, the old wall's "foot" exists in the garage. Is it possible to chisel this away without risking the wall's integrity? Could someone be kind enough to explain its purpose? The garage's concrete floor seems to be floating against the rest of the house
Question 4: What types of drawings are needed? An overview drawing where the basement is seen from above, as well as from the inside of the house towards the door opening where the support beam is drawn in?
I have tried contacting someone who can calculate it for me, but unfortunately, it seems everyone is on vacation (not very surprising, perhaps, but unfortunate for me). If it is the forum's opinion that someone must calculate it, what information is needed? Is there anyone on this excellent forum who can help me with that?
We usually order calculations, as you do not always have all the prerequisites to make your own decisions when demolishing load-bearing structures. What you often have to do is over-dimension if you are unsure. If you purchase the service, you go down to the beam dimension that can handle the load with a safety margin.
To over-dimension, you need to have references from previous projects and estimate this against your conditions.
You need to fit in a door with a 910 mm opening, usually not an issue, with supports on each side of the door about 100 mm, i.e., a beam of 1100 mm.
This probably works with an IPE beam 120. But this is not the whole truth as we don't have the load, i.e., the span length of the joists using the wall as a support. So we can calculate the load on the wall. If you have an area of 20 sqm that the wall needs to support, it is 200kg x 20, i.e., 4 tons, divide this by the wall length, which I assume is 5 meters, it becomes just under 1 ton per meter. What deflection does an IPE 120 have with a 1-ton distributed load, and do the supports handle 500kg more than before? As I am not a designer, I don't know, but in previous jobs, I've seen that it might manage with a 120 beam, but then I choose to over-dimension, so I take an IPE 160. Not that I would have done it, but as a hobby amateur, you can do so.
I do not recommend it and add a few questions you should have answers to, otherwise you should hire someone to carry this out (risk of greater damage than saving 15,000 kr).
How do you solve the fastening at the supports?
Do the supports handle the new load? No cracks or similar?
Do you know how to brace when you tear down so as not to cause settlement in the joists?
Where will you place the props to bring down the load to the floor below so it does not cause cracks?
Underpinning the supports or between the joists and beam? Expanding concrete or regular?
Height between beam and joists to benefit from the expanding concrete.
Regarding your ledge under the wall, it is a foundation that distributes the load from the wall into the ground, and you cannot remove it.
