Stairs are one of the features of a design that can take an inordinate amount of time to design. (Toilets are another.) The reason is invariably that the layout decided upon in Schematic Design doesn't work out upon closer inspection in Construction Documents. Finding out that you need an extra 2’ leads to a bad day. Finding 2' means re-design.
The technical considerations of stairs that I’m talking about are selection of materials, and structural detailing. Here is how I usually proceed. The vast majority of buildings we have designed are Type 2B, which back in the day was known as “unprotected non-combustible”. That ’non-combustible’ part all-but-eliminates wood stairs. But other issues that work against wood are the width of stair required in non-residential buildings and the difficulty of joining the members structurally. It may sound odd but it is much simpler to build a steel stair.
There are four components of a stair finishes that need consideration - Stringers, Hand Rails, Guards, Treads/Risers. When I am working out a stair configuration and basic structural considerations, I find that is it helpful to have a concept of what I want the final stair to look like. This might take a half hour longer during the early design, but it can save you hours of changes later.
Utilitarian Stairs are used for fire exits, industrial buildings and and other "backstage" locations. These stairs are almost always steel because of the building's Construction Type or the configuration that the stair must take. Steel allows for bent stringers, and balusters that will hold up over time.
Guard Rails and Handrails are needed in several locations in buildings - stairs, ramps. mezzanines, floor openings, etc. The building code and ADA accessibility regulations have an impact on placement, heights, and configuration.
Roof access seems to have become more important to me as I got older (wiser?). Two realizations dawned on me. 1. Climbing a ladder to visit a roof is pretty ’thrilling’ for the unaccustomed. 2. How is anyone motivated to maintain the roof and the stuff up there if they can't easily get to ’up there’. Reason 2 is the main reason to build easy access to the roof into every project - even a remodeling.
Roof Access is critical in commercial buildings especially if there is mechanical equipment located on the roof (flat roof). The traditional 30"x36" roof hatch and vertical ladder are inadequate. Maintenance of both the roof and the equipment located there require easy and safe access for inspection and bringing tools and filters onto the roof. The taller the building the more necessary this roof access becomes.
Spiral stairs are a specialized solution to accessing another story or level. Theaters and equipment mezzanines are the main uses for a spiral stair. A residence in need of a little drama is another use.