Spiral Staircase movement

[Robin2020]

The lightweight staircase moves when in use. It's fine I guess but did come with a small wall bracket (shown in pic). I wonder if it's worth fitting one. I would need to get a much bigger one made as its old limestone behind the tanking.
I just wonder if the movement will eventually crack the stone, and then my insulated plasterboard will move and crack...
Loads of these are fitted with no option of a wall support so people clearly live with the bounce...
Any thought? I think a huge brace would be needed with chemical anchors and all sorts..

 

[Welderloon]

If the kit was supplied with a wall bracket then I'd fit it, if you feel it needs to be longer & stronger then go for that.
Any modifications are better & easily done in a pro-active approach during installation rather than a reactive attempt at a later date with the resultant cosmetic/aesthetic issues that may occur.
If you have concerns around the bounce on the bracket then fit rubber absorption blocks.

 

[HatsOff]

Is it fixed to the first floor securely? I'd have thought that would do enough to reduce any movement. You could lay some restraint straps to the next few floor joists to reinforce the edge trimmers.

 

[Zebbedee]

The wall bracket looks like it would only really help the one step? Put a bit of wood support down to floor where the wall support would be as a trial first I think

 

[Robin2020]

Thanks guys...I think on a half way step it must make some kind of difference if done right. I will try a column of wood today to see if that helps....I will also cut the membrane and check the stonework behind for options.

 

[Welderloon]

Ensure the base plate is secured as per spec, for a spiral there should be a recommended concrete plinth size or extra joist bracing to accommodate & withstand while also minimise the hinge/lever effect created.
Hopefully this has been done properly

 

[Wesley]

I imagine the bracket is to take any sideways flex out of the upright. The top of the pole is where you’ll get most of the force, so make sure its fixed well.

 

[AlCapone]

There are no supports under steps
Not good at all

 

[Wilksy]

The way the balastrades hook under the treads I’d say if you bracket it under one of those that would stiffen the handrail up mid way on the stair, is there room between the wall and plasterboard to hide a vertical support?

 

[Robin2020]

I tried a small acroprop under the middle tread. Zero change.
Yes the pole is bolted on the concrete slab and screed poured around it. So proper job. You can see the top triangular tread has 3 solid brackets connecting to a thick joist.
Essentially each tread is connected to the one above so not a robust design. A bit like walking down a spring. However it is not that bad.
I can't see how holding one part of a spring will stop it moving so I have decided not to bother .

 

[HatsOff]

What happens to the top of the post?

To get a post to properly cantilever would take a large baseplate with stiffeners but I suspect it was just a flat base plate.

 

[Lakesdigger]

Is the centre post one piece or sections? Ultimately other than the strength of the centre post the only other thing the staircase is reliant on for stiffness is the handrail as in effect the outside of the treads are hung from it.

 

[Wesley]

You'll never get away from a bit of flex. Any movement at the top of the centre post will exaggerate it. I would’ve thought thats what the bracket is for. To stiffen up the post rather than holding up a tread.
I’ve got a spiral style staircase that goes through 180 degrees. But got solid risers. Was to replace similar style but previous one went into the wall as it curved around. Don’t think you’ll get away from a bit of movement. Problem I’ve got is it turns out the glue they used between risers & treads wasn’t for structural purposes. The flex has put loads of stress on the glue & screws. Daft sods should’ve known better. Full strip down & rebuild needed one day…

 

[Robin2020]

What happens to the top of the post?

To get a post to properly cantilever would take a large baseplate with stiffeners but I suspect it was just a flat base plate.

The top of the post has a bug nut on to that pulls on studding which holds the 2 post sections together...

 

[Robin2020]

You'll never get away from a bit of flex. Any movement at the top of the centre post will exaggerate it. I would’ve thought thats what the bracket is for. To stiffen up the post rather than holding up a tread.
I’ve got a spiral style staircase that goes through 180 degrees. But got solid risers. Was to replace similar style but previous one went into the wall as it curved around. Don’t think you’ll get away from a bit of movement. Problem I’ve got is it turns out the glue they used between risers & treads wasn’t for structural purposes. The flex has put loads of stress on the glue & screws. Daft sods should’ve known better. Full strip down & rebuild needed one day…

Yes I agree...hard to prevent movement unless you get an old cast metal type.
I doesn't help that I have a 160cm diameter version so a larger moment on each tread..
How annoying about your treads...grrr

 

[Robin2020]

Is the centre post one piece or sections? Ultimately other than the strength of the centre post the only other thing the staircase is reliant on for stiffness is the handrail as in effect the outside of the treads are hung from it.

Centre post is steel sections linked with 20mm studding. Handrail does nothing...its crappy plastic pipe. A sore subject as I thought it was going to be oak!!!

 

[renewablejohn]

Looks like you have a very cheap copy of an old victorian spiral staircase. The old victorian spiral sections would be a cast iron ring with T bar off it and a T at the end of the other T bar which the hand rail uprights would attach to. The wood step would then be screwed to the T bars to stop the wood from flexing. Without the T bars I am not surpised the wood is flexing. What concerns me more is that the timber used is just glued laminated so I hope you keep it very dry as if it gets wet it has a very nasty habit of delaminating.

 

[Will Blackburn]

The bracket is surely just to stymie horizontal flex. All vertical load is taken by the centre pole.

 

[Wesley]

What concerns me more is that the timber used is just glued laminated so I hope you keep it very dry as if it gets wet it has a very nasty habit of delaminating.

I expect he has a roof over it to do that. Don’t know many people that would chuck buckets of water over their stairs either so I’m sure it will be fine

 

[Will Blackburn]

I expect he has a roof over it to do that. Don’t know many people that would chuck buckets of water over their stairs either so I’m sure it will be fine

Plenty of swimming pool roofs held up by laminated wooden beams.