I have started a project to open up a previously closed U-staircase.
I began by loosening the riser on the weakest step in the lower turn to see how it felt. It turned out that the step started to flex too much. Therefore, I'm considering if there are any good ways to reinforce it, or if I should reattach the risers and tighten the staircase again.
The treads are 30mm thick in total and are a laminate construction with a 25mm laminated core and a surface layer that appears to be solid wood/veneer with a thickness of 2-3mm each.
Right now, I'm leaning towards cutting steps from 12 or 15mm oak plywood and gluing it on top. That way, I get a new nice surface layer and reinforcement at the same time. I've calculated the deflection, and with a 100kg point load in the middle of the step, this operation reduces the deflection from 9mm to about 2mm. I've calculated this using an E-Modulus of 9 GPa and a homogeneous cross-section.
Now we come to the question. Will I achieve the reinforcement I expect through the gluing as I described above, or are there smarter ways?
A follow-up question is what is stiffer: plywood or solid? I think plywood should be weaker as you compromise strength in one fiber direction for gained strength in the other. But I don't know.
To clarify, I intend to glue the reinforcement on top of the existing step and do not plan to let the reinforcement extend into the stringer.
Thank you in advance,
David
I began by loosening the riser on the weakest step in the lower turn to see how it felt. It turned out that the step started to flex too much. Therefore, I'm considering if there are any good ways to reinforce it, or if I should reattach the risers and tighten the staircase again.
The treads are 30mm thick in total and are a laminate construction with a 25mm laminated core and a surface layer that appears to be solid wood/veneer with a thickness of 2-3mm each.
Right now, I'm leaning towards cutting steps from 12 or 15mm oak plywood and gluing it on top. That way, I get a new nice surface layer and reinforcement at the same time. I've calculated the deflection, and with a 100kg point load in the middle of the step, this operation reduces the deflection from 9mm to about 2mm. I've calculated this using an E-Modulus of 9 GPa and a homogeneous cross-section.
Now we come to the question. Will I achieve the reinforcement I expect through the gluing as I described above, or are there smarter ways?
A follow-up question is what is stiffer: plywood or solid? I think plywood should be weaker as you compromise strength in one fiber direction for gained strength in the other. But I don't know.
To clarify, I intend to glue the reinforcement on top of the existing step and do not plan to let the reinforcement extend into the stringer.
Thank you in advance,
David
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If the steps are 30 mm thick and bend 9 mm, they must be pure crap, if the expression is allowed.
Wouldn't it be better to make new steps in 30 mm instead of gluing on an additional 15 mm, which will look really clumsy?
Wouldn't it be better to make new steps in 30 mm instead of gluing on an additional 15 mm, which will look really clumsy?
I understand that 30mm is quite normal and have also noticed that it flexes a lot.
The measured deflection is about 3mm with an 80kg load.
The figure 9mm came from the theoretical calculation which also assumed a general width of 300mm on the step and a length of 1400. The purpose of the calculation was mostly to get an idea of the expected relative difference I could expect. The measurement of 1400 is also at the "point," it's 1200 on the front of the step. The actual step is also a bit more complicated than the theoretical comparison since it's a corner step with about 450mm at the outer end and only 60mm connecting width against the inner stringer.
The idea is a budget renovation, and completely new steps get too expensive, I feel. If there's no alternative, it might end up being covered again.
As for clumsy, it's quite common to have 40mm steps, so 42-45 can't be that bad.
Is my solution completely unacceptable?
The measured deflection is about 3mm with an 80kg load.
The figure 9mm came from the theoretical calculation which also assumed a general width of 300mm on the step and a length of 1400. The purpose of the calculation was mostly to get an idea of the expected relative difference I could expect. The measurement of 1400 is also at the "point," it's 1200 on the front of the step. The actual step is also a bit more complicated than the theoretical comparison since it's a corner step with about 450mm at the outer end and only 60mm connecting width against the inner stringer.
The idea is a budget renovation, and completely new steps get too expensive, I feel. If there's no alternative, it might end up being covered again.
As for clumsy, it's quite common to have 40mm steps, so 42-45 can't be that bad.
Is my solution completely unacceptable?
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Talked a bit with a local fine carpenter today, and the conclusion is to cut stair treads in 18mm laminated oak board and glue them on top of the existing ones. This way, just like with plywood, I get the surface layer included, but it will be even stronger and also cheaper. If anyone is interested, I can upload a few pictures of the process.
Feel free to share more opinions about the solution. A weekend in Åre lies between now and the start of construction, so there's still an opportunity to reconsider.
Feel free to share more opinions about the solution. A weekend in Åre lies between now and the start of construction, so there's still an opportunity to reconsider.
It was a few years ago, but if you still have the pictures, feel free to upload them!D David_Berglund said:
It quickly happened that we found another house that we liked, so after making some progress, we decided it was easier to restore the staircase, so all the risers were reinstalled, and the staircase was repainted and restored as it was. A lot of work for nothing, but we're happy with the new house. 