Hello,
Is there anyone here who knows how to calculate the tread width and the curve of the stringers (side pieces) when building a curved staircase? I'm planning to replace my ridiculously narrow and steep straight staircase with one that turns ninety degrees.
The steps are usually of equal width at the beginning of the staircase and then become wedge-shaped the closer you get to the turn... do you try to maintain the same tread width in the middle of the staircase or how does it work??
Is there a formula or a staircase expert one can consult? I assume there is also some minimum measurement for tread width and riser height. Grateful for any advice or tips.
Best regards, Njitnjau
Is there anyone here who knows how to calculate the tread width and the curve of the stringers (side pieces) when building a curved staircase? I'm planning to replace my ridiculously narrow and steep straight staircase with one that turns ninety degrees.
The steps are usually of equal width at the beginning of the staircase and then become wedge-shaped the closer you get to the turn... do you try to maintain the same tread width in the middle of the staircase or how does it work??
Is there a formula or a staircase expert one can consult? I assume there is also some minimum measurement for tread width and riser height. Grateful for any advice or tips.
Best regards, Njitnjau
"Also, I assume there is a minimum measure for tread width and riser height..."
Indeed, there is. We'll start with a straight staircase.
The riser height should not exceed 180 mm. The tread width is adjusted according to the height. For example, if you have a 2700 mm floor-to-floor height, the riser height becomes exactly 180 mm, resulting in 15 risers.
But that ideal measurement is rare. You should take the exact floor-to-floor height as a starting point and ensure that the riser height doesn't exceed 180 mm.
Say it's 2600 mm instead. 2600/180 gives 14.4 risers. But you can only have whole risers. Then you have to choose: either 14 steps (185.71 mm) or 15 steps (173.333 mm). Based on the number of risers, you get the number of treads, which is one less than the number of risers since the uppermost floor serves as the last tread. That is, 13 or 14 in the example.
Then apply the formula: b + 2h should be between 570 and 630 mm. The first is the average step length for women, the latter for men. So you can have a step length from 570 to 630 mm. The closer to 570 mm, the shorter and steeper the staircase.
Thus: 570-2h=b, or 630-2h=b gives the tread width. To the width measurement, add a nosing of maximum 30 mm so the heel fits when descending the stairs. The nosing only makes the staircase longer once as it overlaps the underlying tread width. That is, the walking line is only one nosing width longer, and that is on the lowest step.
In a straight staircase, you can place the walking line anywhere on the width if it doesn't exceed 1200 mm. In a winder staircase, it should be placed 400 mm from the outer curve, measured from the handrail. That is, about 500 mm from the wall.
Therefore, draw the staircase in plan and mark the tread width equally on the walking line all the way, even in the turn. Then moderate the tapering according to these marks so that you don't have too narrow tread widths in the inner turn and too wide in the outer turn.
You can also solve it graphically by aligning a straight line with the tread widths parallel to the long part of the staircase and transferring the tapering from that line to the staircase, but it's difficult to explain what it should look like. The end result tends to be quite similar with both methods.
_________________
Byggaren
Indeed, there is. We'll start with a straight staircase.
The riser height should not exceed 180 mm. The tread width is adjusted according to the height. For example, if you have a 2700 mm floor-to-floor height, the riser height becomes exactly 180 mm, resulting in 15 risers.
But that ideal measurement is rare. You should take the exact floor-to-floor height as a starting point and ensure that the riser height doesn't exceed 180 mm.
Say it's 2600 mm instead. 2600/180 gives 14.4 risers. But you can only have whole risers. Then you have to choose: either 14 steps (185.71 mm) or 15 steps (173.333 mm). Based on the number of risers, you get the number of treads, which is one less than the number of risers since the uppermost floor serves as the last tread. That is, 13 or 14 in the example.
Then apply the formula: b + 2h should be between 570 and 630 mm. The first is the average step length for women, the latter for men. So you can have a step length from 570 to 630 mm. The closer to 570 mm, the shorter and steeper the staircase.
Thus: 570-2h=b, or 630-2h=b gives the tread width. To the width measurement, add a nosing of maximum 30 mm so the heel fits when descending the stairs. The nosing only makes the staircase longer once as it overlaps the underlying tread width. That is, the walking line is only one nosing width longer, and that is on the lowest step.
In a straight staircase, you can place the walking line anywhere on the width if it doesn't exceed 1200 mm. In a winder staircase, it should be placed 400 mm from the outer curve, measured from the handrail. That is, about 500 mm from the wall.
Therefore, draw the staircase in plan and mark the tread width equally on the walking line all the way, even in the turn. Then moderate the tapering according to these marks so that you don't have too narrow tread widths in the inner turn and too wide in the outer turn.
You can also solve it graphically by aligning a straight line with the tread widths parallel to the long part of the staircase and transferring the tapering from that line to the staircase, but it's difficult to explain what it should look like. The end result tends to be quite similar with both methods.
_________________
Byggaren
I have 2750mm floor to floor. Today the step height is 215mm and the length is 2300mm. So that's the floor area covered by the staircase. 13 steps including the upper floor. Step width 215mm. It feels like you might fall down every time you walk on it...
I'm thinking of rebuilding it to be 2300mm forward and 1700mm to the right, with a staircase width of 1000mm.
So it will be a very small staircase. Not sure yet if I can make it work... Maybe I have to enlarge the opening a bit...
Best regards, njitnjau
I'm thinking of rebuilding it to be 2300mm forward and 1700mm to the right, with a staircase width of 1000mm.
So it will be a very small staircase. Not sure yet if I can make it work... Maybe I have to enlarge the opening a bit...
Best regards, njitnjau
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Thank you so very much! It looks really great! Incredibly kind!
The riser height in your case will be 196mm
I tried drawing a sketch by hand with 15 steps and got a riser height of 183mm and a tread width of 200mm + overhang of 30mm. It should be noted that I increased the lower stringer by about 50mm
Which is preferable: more steps but narrower width or fewer steps but slightly higher riser height and wider steps..?
Kind regards, Njitnjau
The riser height in your case will be 196mm
I tried drawing a sketch by hand with 15 steps and got a riser height of 183mm and a tread width of 200mm + overhang of 30mm. It should be noted that I increased the lower stringer by about 50mm
Which is preferable: more steps but narrower width or fewer steps but slightly higher riser height and wider steps..?
Kind regards, Njitnjau
njitnjau said:
As long as 2h+b stays within 570-630 mm, you can choose what suits you best, but aim more towards 630 mm. That way, the staircase will be easy to walk in.
I also have to give credit to Immobil for his illustration/computer-drawn staircase. This is the second time h*n has done one that describes what I said in a good way.
___________________
Byggaren
Immobil, how did you draw it?
With some program for creating stairs or like freehand?
Nice job in any case.
With some program for creating stairs or like freehand?
Nice job in any case.
Impressed by Immobil's staircase design. I would like to have such a program now that the staircase construction is approaching. I have drawn and designed everything else in the renovation and extension...
FarsanSeger
www.jogarsrud.se
FarsanSeger
www.jogarsrud.se