albini & fontanot stairs

Hi,
I'm trying to find out the strength required for the top support for a set of albini and fontanot modular stairs. The stairs are called Kompact U 89. They are bolted to a top support and slotted together from the top down until they reach the floor, where they are also fixed. In the middle there is the need for an "intermediate support" if the flight is over 7 consequetive steps, which mine is (13).
I can't find anything from the manufacturer on the web - and one salesmen said "no one has asked me that before". and I can't get any figures from any of the UK suppliers so far.
I have found an old italian catalogue for a similar set of stairs, this had a diagram of a concrete beam 180mm high by 200mm wide at the top with 120mm bolts into it. I really do not want to use such a massive beam, especially not concrete. Another salesman said he knew someone who had the stairs resting on a lath and plaster wall!
Has anyone used these stairs in any project? what did you do? where is the weight mostly? hanging from the top or transfered to the bottom? what is the assumed load on a stair, besides it's own weight?
Any help would be really appreciated...
Cheers
Philip
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<<snipped>>
A staircase is like a ladder and, depending on its construction, should be used in the same sort of way. A ladder is placed against a solid object that is known not to be so weak as allow the ladder to fall through it. So your staircase would need to be like the ladder against a wall, but remember that the support is going to take the weight of the stair and also more than one person using it at a time.
The other specification for a ladder is that it be supported at the bottom to prevent it from slipping away from the support of its angle, i.e. the wall. So your staircase will need to be fixed at the bottom to stop it slipping away from the top support that you know is going to take the weight which you want the stairs to take.
If you have a landing at the top of the staircase that you know takes the weight of many people standing on it at one time, then I'm sure you could assume that this landing will be suitable to support the top of the stairs.
If you know that the floor you're setting the bottom of the staircase on to is suitable to take the weight of many people standing on it, then you could also assume that fixing the staircase to it, so that it will not slip away when in use, should also be fine.
Now, depending on how flexible your staircase is, just like a ladder, you should be able to work out how many supports it needs to stop it breaking in between the top and bottom supports when people are running up and down on it.
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Thanks for you reply BigWallop. I forgot to put a link in to show the typr of stairs. Here it is: http://www.stairs-direct.co.uk/Assets/pdfs/installation_instructions_kompakt.pdf
you can see - the steps fit together like vertebrae of a spine.
I also need the stairs to wind round through 180 deg like a spiral. does this not have an impact on the loading? I wondered if anyone has a weight for the staris or even a knowledge of a reasonable assumption for loading ON a stair (i.e. reasonable from the point of view of the building control inspectors.
I think I understand there are those that consider what practically works to be what one does. But then there are those that consider it important to abide by regulations, for future piece of mind.
Although I lean to the former on an optomistic day, my pessimistic half has won and I'm getting out the chequebook and stumping up the building control fee for the full plans. So I can afford this - I've drawn the plans myself and I hope to do the sturctural calculations myself with some free software (fastrak simple beam design)
.What I need is the loading on the beams. I can't get these figures easily and I was wondering if anyone has put these stairs in before or has done this type of calculation before. As I said - what do the stars weigh? and what loading is standard to assume on a stair? I think I read 0.25 kN/m2 is loading for the actual floor (if only a single habitable room used as a bedroom)
Hope someone can help.
Maybe Hugo has some idea, I've based my entire loft plans on his FAQ and the Swansea guide. I'm really grateful for these wonderful resources.
I really hope the plans go through, I would advise anyone to pay for plans to be drawn after the time I have spent researching and drawing. (Why am I willing to work for 10p per hour in my own time on this? Is it because I'm committed now the roof windows are in and I have male pride?)
Regards
Philip
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<<snipped>>
So it should look something like this:
<http://www.the-wooden-hill-company.co.uk/karina/karina_space_saver_staircase.htm
when it's finished ?
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Hi BigWallop,
Yep - but not the space saver style - this model...
http://www.the-wooden-hill-company.co.uk/kompact/kompact_modular_staircase.htm
I just got a post this evening from Bill Howe who sells the stairs in the UK giving the following information:
The weight of a 14 riser Kompact 89 is listed as 288kgs., if you are thinking of putting an outside handrail on it would add extra weight, so I would suggest 300kgs would be a nice round figure to work on.
so, am I close to understanding what specification the beam should be?
I've just had a nasty shock and realised I have to pay even more for my building control fee than I though because the loft room will be over 10m2 floor area. It works out at 150 ish for plan fee and 350 ish for inspection fees. This makes it even less likely that I can afford a structural engineers report!
Philip
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<<snipped>>

The weight should be evenly distributed over the bottom floor and the intermediate supports that you set in between the full height of the rise, so the weight issue is only a major factor if you are setting the staircase onto a soft or flexible floor structure. The top of the staircase is only resting against the top landing and, as said before, as long as you know the top landing can support the weight of a few people standing on it, them it should be able to take the weight of the top few treads of the staircase resting on it.
The .PDF file links at the bottom of the website you link to show a great example of how these stairs go together. You'll also have to check with your local authority that these designs of staircases are allowed under their fire escape regulations if the installation is for a habitable loft conversion.
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