U-shaped stairway design

[MushCreek]

We're really getting close now! I'm still tweaking details, and am trying to figure out the exact stairway dimensions. I know that code requires a minimum of 36" wide, and that the handrail can intrude into this space. I've been drawing my stairways with a full thickness wall (4-1/2") in between the two sets of stairs.  Basically, there is a common wall between the upper and lower flights, which adds up to 4-1/2" with a 2X4 plus 1/2" drywall on each side. The total width would then be 78-1/2", not including the wall thickness outside of the stairway. Is this as narrow as I can make it, or is there a way to make it a bit narrower? I don't mind the stairs being open (with a railing) on one side, rather than a solid wall, if I could figure out how to build it. These are basement stairs, but sometime in the future may get more traffic if we finish the basement. And of course, I have to meet code.

[UK4X4]

I'm at 76" on my rough design

with the center being 4"

But really if its non supporting I don't see a major reason why it can't be narrower

But you then hit the min 6" width for the steps around the U- I have'nt looked at that yet...so I may need to go wider or longer and stick in a log post to get the inner edge width restriction

[Don_P]

I'm coming up w/ 77.5" frame to frame minimum;
.5/36/4.5/36/.5

[MushCreek]

I'm not going to have winder steps- just a rectangular landing at the halfway point. I don't know where I got 78-1/2" except that I've been using 37" as a width since I don't want to cut it too close and flunk the inspection. I guess that's as narrow as I can go then- 76-1/2"? Would it be code legal to make the center wall thinner, say turn the 2X4 sideways to 1-1/2" rather than 3-1/2"? I guess I'm really splitting hairs here....

[Don_P]

It's a hair splitting part of the house 
Inside of finishes, above the rail, they must be 36 or more wide. There is no requirement for a wall at all between flights, a handrail is required, which may encroach on the 36" min width. It is pretty easy and relatively safe to put one step in the middle of the platform if you need to. Depending on the set I've had to really parse out the code. Most are looking for a good common sense set but I had one guy that measured every step and all the heights/spacings,etc. I figured stairs had been their last training session.

[MountainDon]

.....but I had one guy that measured every step and all the heights/spacings,etc..

Those are the guys who give code a bad name......