I am planning to build a "self-supporting" staircase with 4 steps according to the sketch below, if possible. My question is what dimension I should use to ensure it holds. The intention is to cut out the steps in the stringers.
Possibly, attachment to the wall on one side is an option.
It is usually about 120mm at the narrowest point, but since it is so short you can probably go with less.
It's mainly the deflection that limits how thin you want to go. Do you have any reasons not to take the fattest rule on the shelf?
Is it going to be painted?
Just under 40 degrees will be the slope if I think correctly.
Maybe it's not a problem if I go with 45x220 and cut out as planned, and possibly screw-glue as much as possible on the insides considering the cut-out?
One way to calculate it is to apply the same deflection criterion normally used for floor joists. Freely translated: a 100 kg person standing in the middle of the stairs should not cause a deflection greater than 1.5 mm on the stringer measured perpendicular to the stair run. To simplify, I only consider the lower free part of the stringer. With a length of 1244 mm and a slope of 40 degrees, the deflection is 1.1 mm if the lower part of the stringer (excluding the cutouts for the steps) has dimensions of 45x70 mm.
One way to calculate this is to apply the same deflection criterion that is normally used for floor joists. Freely formulated: a 100 kg person standing in the middle of the stairs should not cause a greater deflection than 1.5 mm on the stringer measured perpendicular to the stair tread. To make it simpler, I only consider the lower free part of the stringer. With a length of 1244 mm and an inclination of 40 degrees, the deflection is 1.1 mm if the bottom of the stringer (excluding the cutouts for the steps) has dimensions of 45x70 mm.
Does this apply even if, like I'm thinking, you cut out for the steps from the stringer?
The angular change is negligible in this case because I calculated a little roughly. If you screw-glue a 45x70 regel on the inside of the vangstycke, the stiffness increases significantly. The deflection decreases to 0.6 mm.
The angle change is negligible in this case because I calculated a bit approximately. If you screw-glue a 45x70 regel on the inside of the vangstycke, the stiffness increases significantly. The deflection decreases to 0.6 mm.
This is what my stringer looks like. It feels stable.
[image]
The stairs I plan to build seem to match yours quite well in terms of measurements.
The difference is that you have 2 attachment points in the second step from the bottom, but probably it won't be an issue in my case without them.
I will try to figure out a good solution for my landing, as well as the "cladding" of the side walls where the staircase will be, then the saw comes out.
harry73 said:
FredrikR said:
The difference is that you have 2 anchor points in the second step from the bottom, but in my case, it's probably not an issue without.