ARRRRRRR!!!!!!!!

Hi David.

-Draw a circle concentric whit the stair
-Use "Full step spiral" (That makes the whole staircase. It does not matter)

-Modify the radius of the stair and place it concentric with the circle.
-Reduce the step of the stair to obtain the first section

-Use again "Full step spiral" for the second section (a horrible stairway will be created but do not worry)

-Modify the radius of thesecond section and place it concentric with the circle. (Voila!!!! It make beautiful)

-Adjust the landing



AAAAARRRRRR!!!!!!!

I'll give it a shot tomorrow when I have a bit more time. Are you certain this works with a spiral stair that has a tight radius? As in a 36" wide stairwell with the inside radius only 8"?

If it's any help I've managed to make a spiral work with a tight inside radius - it's only a single storey but should work for 2 storeys.

It was a heck of a job to design though - I drew out as best I could in 2D based on the relevant British Standard (see sketch attached) and then aligned as best I could Revit's attempt at a spiral via the stair tool.

As you can see it isn't a perfect alignment but it was the best I could achieve - and this was to go to the steel erector (well, 'blacksmith' we still call them here in Hobbiton ) who had his own ideas on design.

Apparently it got built and passed Building Regulations.

This was on a private residence - if it had been say, an escape stair from a commercial building I don't think such a tight radius would have been allowed in the UK - I seem to recall doing them as helical stairs in the past - i.e. with a much greater internal radius.