Winder layout

[Don_P]

Someone asked for help with figuring out a set of winders. I thought it might be helpful to answer here.
We were fixed by a wall 6'2-1/2" in. The finish floor to floor dimension is 102-1/2". This is a sketch showing a 3' wide stair laid out in plan view on the floor. I've also drawn within it a 12" walkline on the stair. The corner of that line is 50-1/2" from the headwall.


The code says that the treads need to be the same width along the walkline and no less than 6" at the narrow end. Dividing that out I came up with about 10-1/8" wide treads. I swung an arc for the 12" walkline and measured the dimension on that chord



Dividing the height out gve me 13 risers at about 7-7/8". Here it is with the tread heights in place


we were worried that a 12' wall might not give adequate headroom, as you can see we are fine there.

[Pritch]

Wow Don!  Thanks for the excellent tutorial. 

[John Raabe]

Nice work Don!

You've really gotten SketchUp to work for you.

[Don_P]

Thanks for the kind words  
Sketchup is very handy for this type of layout. Stairs are real tough to visualize and are one of the first things to check in a design to see if it "works". They are one of my first checks when I'm given a set of prints.

With this figured out first in plan view, flat, its easy to get the treads to work. From there I used the push/pull button and just lifted each tread up to its' correct height.

This is showing finished heights and riser faces so there is considerable thinking yet to frame these, this is probably not a beginner set without taking it real slow and thoughtful, but in a tight space you gotta do...

The next stop would be to take this sketch to the inspector and have a sit down before beginning to make sure he is in agreement with the measurement methods, there are a couple of ways of looking at it. It used to be that close was good enough to satisfy intent but I have had an inspector measure every tread, this sure isn't a set you'd want to do over.

[NM_Shooter]

Son, 'round here a winder has glass in it and you look through it.