I'm seriously considering building my own staircase to the upper floor since the old one was removed during the renovation.
The idea is to have 2 underlying stringers cut from laminated beams.
The length will be about 4600 mm, the question is how strong the beam should be?
If you only consider the part that remains after the steps are cut out.
In the image below, the measurement is 120 mm, is that sufficient?
I also want to ask the easiest way to cut out for the steps?
If we assume a 2.40m ceiling height + the thickness of the joists, and a 45-degree slope, which is on the steep side. Then you get a length (span) of about 4m. If a joist with that span were to be built, you would need 195 - 220mm joists. And as mentioned, you probably should count on 4.5 - 5m to get a comfortable slope (google "stair formula" for the right ratio between riser height and tread depth).
If we assume a 2.40m ceiling height + the thickness of the joist, and a 45-degree slope, which is on the steep side. Then you have a length (span) of about 4m. If one were to build a joist with that span, you would need 195 - 220mm beams. And as mentioned, you should probably expect 4.5 - 5m to get a comfortable slope (google "stair formula" for the correct ratio between step height and step depth).
I also think that 120 is way too weak. However, I don't quite think you can calculate it the same way as for a floor joist since the load doesn't go perpendicular to the narrowest section of the beam.
A reasonable solution, I think, is not to notch the beam but instead attach the steps to the side of the stringers.
No, one should probably size based on the vertical section. That is, in the same direction as the load occurs.
Our staircase has a cross-section on the stringers of about 280 mm
A staircase with a 45-degree incline _should_ therefore manage with a 195 rule, but note well that this is the unsawn dimension, that is, what is left after the cutouts for the steps.
