Hello everyone,
We have a spiral U-shaped concrete staircase with a landing and want to build a railing on the inside that is as slim as possible. Since a masonry version would take up too much space, we would like to realize the railing as thin as possible using drywall construction.
For this, I thought about attaching horizontal UW profiles to each stair tread and a vertical UA profile to the stair tread itself. I’ve attached a sketch to illustrate this.
I would use a 50mm (2-inch) profile and fix 12.5mm (0.5-inch) gypsum fiberboard on both sides. That would give a total thickness of 7.5cm (3 inches).
I have two questions and hope you can help me out:
1. Would this construction be stable enough as a stair railing? Since it’s on the inside of the staircase, the railing stands free without a wall connection.
2. With a 50mm (2-inch) profile, the anchors would be placed in the center. Adding the 12.5mm (0.5-inch) board means the anchor would be positioned 37.5mm (1.5 inches) from the edge. I’m a bit concerned that the concrete might chip here. Maybe not when drilling the hole, but possibly when fastening the anchor, or if someone falls against the railing. An alternative would be chemical anchors, but there is still the concern of concrete spalling under pressure on the railing.
What do you think?
cheers
We have a spiral U-shaped concrete staircase with a landing and want to build a railing on the inside that is as slim as possible. Since a masonry version would take up too much space, we would like to realize the railing as thin as possible using drywall construction.
For this, I thought about attaching horizontal UW profiles to each stair tread and a vertical UA profile to the stair tread itself. I’ve attached a sketch to illustrate this.
I would use a 50mm (2-inch) profile and fix 12.5mm (0.5-inch) gypsum fiberboard on both sides. That would give a total thickness of 7.5cm (3 inches).
I have two questions and hope you can help me out:
1. Would this construction be stable enough as a stair railing? Since it’s on the inside of the staircase, the railing stands free without a wall connection.
2. With a 50mm (2-inch) profile, the anchors would be placed in the center. Adding the 12.5mm (0.5-inch) board means the anchor would be positioned 37.5mm (1.5 inches) from the edge. I’m a bit concerned that the concrete might chip here. Maybe not when drilling the hole, but possibly when fastening the anchor, or if someone falls against the railing. An alternative would be chemical anchors, but there is still the concern of concrete spalling under pressure on the railing.
What do you think?
cheers
O
Osnabruecker26 Dec 2019 23:06For high-quality anchors, there should be a datasheet specifying the distances to the outer edge.
If you are working within the millimeter range, keep in mind that the anchor is centered at 37.5 mm (1.5 inches). This means the outer edge of the anchor moves even closer to the concrete edge. Depending on the design, this edge is already structurally likely to fail.
Also, the two anchors in your sketch that nearly meet at the tip would likely cause the corner to break off.
Is the staircase already built? You could embed anchor baskets in concrete, but make sure to check the datasheets beforehand.
Is it possible to anchor something on the side? Then you could install a post with, for example, four anchors and fill the space in between with, for instance, glass panels.
If you are working within the millimeter range, keep in mind that the anchor is centered at 37.5 mm (1.5 inches). This means the outer edge of the anchor moves even closer to the concrete edge. Depending on the design, this edge is already structurally likely to fail.
Also, the two anchors in your sketch that nearly meet at the tip would likely cause the corner to break off.
Is the staircase already built? You could embed anchor baskets in concrete, but make sure to check the datasheets beforehand.
Is it possible to anchor something on the side? Then you could install a post with, for example, four anchors and fill the space in between with, for instance, glass panels.
Hey, thanks for the tip. I spent some time today looking into the anchors, and there aren’t many options, but apparently, some do exist.
The minimum edge distance for standard anchors from Fischer is 30mm (1.2 inches) and for chemical anchors, it’s 40mm (1.6 inches). For the chemical anchors, a shear load of 5.1 kN is specified at an edge distance of 95mm (3.7 inches). Unfortunately, there’s no shear load data given for 40mm (1.6 inches), but calculating it linearly results in about 2 kN. Larger distances are also roughly calculated linearly. Unfortunately, there is no information about the shear load capacities of the 5x25 or 6x50 anchors.
I attached a drawing again. It should actually fit exactly, and if I take the shear load from the chemical anchor and convert it, I end up with 1.5 kN, which corresponds to 150 kg (330 lbs). If I use two anchors per staircase, that should be sufficient, even if the actual load per anchor is only 1 kN.
Thanks also for the hint regarding the corner. I definitely have to place the anchors as far away as possible. I need to take the exact measurements since the staircase is already built. So all options that could have been considered beforehand are off the table :-/ The problem was we were told the wall could be made narrow. But the structural builder said he would not build anything below 12 cm (4.7 inches) thick because it wouldn't be stable enough. The staircase was already there at that point.
The stairwell opening is 1 cm (0.4 inch)... so almost non-existent. Also, we don’t want posts with glass or anything similar in between. We would prefer something solid.
The minimum edge distance for standard anchors from Fischer is 30mm (1.2 inches) and for chemical anchors, it’s 40mm (1.6 inches). For the chemical anchors, a shear load of 5.1 kN is specified at an edge distance of 95mm (3.7 inches). Unfortunately, there’s no shear load data given for 40mm (1.6 inches), but calculating it linearly results in about 2 kN. Larger distances are also roughly calculated linearly. Unfortunately, there is no information about the shear load capacities of the 5x25 or 6x50 anchors.
I attached a drawing again. It should actually fit exactly, and if I take the shear load from the chemical anchor and convert it, I end up with 1.5 kN, which corresponds to 150 kg (330 lbs). If I use two anchors per staircase, that should be sufficient, even if the actual load per anchor is only 1 kN.
Thanks also for the hint regarding the corner. I definitely have to place the anchors as far away as possible. I need to take the exact measurements since the staircase is already built. So all options that could have been considered beforehand are off the table :-/ The problem was we were told the wall could be made narrow. But the structural builder said he would not build anything below 12 cm (4.7 inches) thick because it wouldn't be stable enough. The staircase was already there at that point.
The stairwell opening is 1 cm (0.4 inch)... so almost non-existent. Also, we don’t want posts with glass or anything similar in between. We would prefer something solid.
O
Osnabruecker27 Dec 2019 21:47To increase the stability of your chipping, consider an off-center drilling of about 50mm (2 inches).
A brief check shows that many railings are designed for values between 0.5–5 kN/m (kilo-newtons per meter) as horizontal load on the rail/top edge. You should also take this into account with the kilograms you assumed.
Everything is calculated just roughly. But if this is not a public escape route for you, at least later you can say "theoretically, it would have been sufficient"...
A brief check shows that many railings are designed for values between 0.5–5 kN/m (kilo-newtons per meter) as horizontal load on the rail/top edge. You should also take this into account with the kilograms you assumed.
Everything is calculated just roughly. But if this is not a public escape route for you, at least later you can say "theoretically, it would have been sufficient"...
In the 50mm (2 inch) version, the pre-drilled holes are centered. Of course, I could use the 75mm (3 inch) version and utilize the off-center holes there. Alternatively, I can also drill my own holes in the 50mm (2 inch) profiles. Sure. I would do that then, thanks for the suggestion.
Another option would be a wooden construction instead of the profiles. I just can’t estimate which would be more stable.
5kN at the top edge is certainly substantial, but probably not necessary for a single-family house. 0.5kN sounds low, but considering the leverage effect... It’s not that simple overall...
Another option would be a wooden construction instead of the profiles. I just can’t estimate which would be more stable.
5kN at the top edge is certainly substantial, but probably not necessary for a single-family house. 0.5kN sounds low, but considering the leverage effect... It’s not that simple overall...
M. Gerd schrieb:
We have a curved U-shaped concrete staircase with a landing and want to build the narrowest possible railing on the inside. Since a masonry version would take up too much space for us,... it would be advisable to share the entire staircase layout here, as that would significantly increase the chances of getting helpful answers.https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Similar topics