The normal method is to run the rafters from the upper wall top down to and over the lower wall. Spacing could be 12 to 24 inches depending on span distances live and dead loads, etc. Depending on the span  that may be accomplished with dimensional lumber, or some type of manufactured truss or rafter. An intermediate beam, parallel to the high and low walls may be used and would need to be engineered.

What are the bldg dimensions? Location or snow load if known?

Those little stubs as illustrated are not the best design.

A roof truss supplier would likely be able to assist in choices for the design. They would need dimensions, location, snow load etc.

Tutorial 91: Curved Stairs II - (17:37 min.)

Version 4.6.7b - 06.26.2026
- Enabled deck railing for spline railing assemblies.
- Added a "GLASS" baluster option for spline railing assemblies.
- Added a "CABLE" baluster option for spline railing assemblies.

Medeek Wall:  Version 4.6.7 - 06.25.2026
- Added a "GLASS" baluster option for curved and straight rail assemblies.
- Added a "CABLE" baluster option for curved and straight rail assemblies.

As I've stated in the recent tutorial the regen time of this spline railings can suffer because of the large poly handrails and/or shoerails.  In the next update I will be introducing and option where the user can toggle a "split" option for both the handrail and shoerail.  This will split those two curved solids into separate segments (at the intermediate posts).  For larger spline railing assemblies my internal testing has shown an almost 100% performance (draw, edit, regen).

These two parameters will be found in the intermediate post sub-menu, see image below:

Version 4.6.6 - 06.23.2026
- Added a Curved Segment option/tool for railing assemblies.
- Added a Spline Railing tool into the Stair Toolbar.
- Spline Railings enabled using a Centripetal Catmull-Rom spline algorithm with user selected start and end tangency points.

Turns out there are many possible solutions to the problem when you go from a single arc to a Hermite biarc solution. Of course not all these solutions are useful, especially where they intersect or collide with other segments of the polyline. Quite the education on this topic between Wikipedia and ChatGPT yesterday. Here as some solutions to the biarc and single arc problem:

Version 4.6.5b - 06.19.2026

- Added a "CABLE" baluster option for curved stair assemblies (circular and elliptical).