there is a thread through history of nesting two stairs around each other, usually to keep male and female separate. i don't know that there would be a 'standard' for this, however, because it takes so many configurations.

at the french chateau chambord it's spirals, designed so that male and female descending to the main floor didn't meet until they arrived.

at the van nelle factory outside rotterdam it's criss-crossed parallel stairs, meant to be an efficient use of space but still keep the genders separate as they went to work in their different areas...a situation which somehow seems more seductive than going up/down the stairs together...


somehow i don't think this is what you mean, but it's the first thing that came to mind.

Can you explain more? Is it two adjacent stairs separated by a fire wall? Is it an alternating tread stair, where each tread is only half as wide as the stair? I'm not sure what you mean by scissor.

Ooh, Steven, that IS a titillating stair...

isn't it? it's funny, i'm surprised anyone ever believed in its purpose. when we took a group of students and made them walk up and down them, separated by gender, they immediately responded with 'whoa, this is the way to get some repressed young workers excited!'

when i trip and fall down the stairs and crash through the window to my death who do i call?

Steven's image is correct except that the stair (if I understand the question correctly) fits within a rated enclosure. The stair itself would need to be rated i.e made of concrete. You couldn’t simply use steel pan. Of course the separation between the stairs is concrete as well. (Filled block perhaps) You simply need to be certain you have enough clearance at each landing. So you’re creating two rated enclosures within one shaft that allows one to satisfy a two means of egress within a minimum amount of space.
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These things get quite massive and often contributing in holding the building up and or responding to a great deal of the shear resistance requirement so it is imporatnt that if you go this route it be placed where yo are getting the most bang for your buck

Beware if your 12' vertical rise issue. If its a fire stair, then you can't go 12' without a landing.

Also check your remoteness ratio - or the distance between the two doors. If they are sharing the same space in plan, chances are that your two doors will be close together (bad).

And then there's the clear headroom in the stair. Check IBC - I think its 7'6.

When you're putting two stairs in the space of one, there's some saving, but be careful that you meet all the other requriements.

I've heard two other theories behind the Chambord stairs. My pops best friend is a Parisian man and took us castle touring when my sisters and I stayed with him a few years back.

He said that the spiral stairs were created so that royalty uses one set and the servants would use the other set. This was done so that they would never have to see each other. He then laughed and said that Francis I had a reputation with the ladies. One stair was for his wife and he would let the mistresses use the other stairs so the wife would never see mistresses leave his bedroom.

All stories follow the same premise: one stair can't see the other stair.

i'd expect that the servants weren't using such a visible and formal stair. when chambord was built, theirs would have been a tiny little thing back of house.

the wife/mistress scenario is funny though, and not necessarily improbable.

when i was in korea, there were a lot of department stores with escalators in this configuration.... with one going up and one going down. sometimes it made things confusing, but it seemed to be an efficient use of space, as well as encouraging customers to browse more (you have to walk through multiple departments to get where you are going)

for a minute there i thought this had something to do with lesbians

Scissor stair is the stair most developers prefer if you can meet all the criteria, as said above. It is the least amount of space for two means of egress possibe. Shared walls of course need to be protected along with the ceiling (which is the stair run of the opposite egress path above your head).

Think double helix.

Here is an example our office did..it is under consruction now. Not the most gracious, but it is efficient.

I practice in Vancouver, canada and I have not done a single building here that did NOT have a scissor stair. They are all we do. Point towers with Scissor stairs, they Rock! Giving you slender towers not big chunky full block buildings. if you are doing Residential towers they are perfect. Nice discreet core with a lobby, two or three elevators and a Scissor stair behind + a small bit of corridor leading to units. Codes will be different depending on where you are writing from. But some other things that you may need to take into account is dead end distances and distance between exits. Here we need to make the exits at least half the tower's diagonal apart. So as the tower plate gets bigger it may be more difficult or impossible to make the scissor stair work.

I have heard a few people say “they cannot be built” and “the fire stopping to the soffits is impossible to get right with movement joints etc.” is there anything in this ? Are they hard to construct ?