I would like to install a (metal) spiral staircase inside my cabin.
The stair will be between the main room (16' x 24') and the mezzanine
(16' x 12')
I did find a company that has many spiral staircase kits sizes to sell
(www.theironshop.com).
I would like to know which size is better to choose to be acceptable
for adults and my dog (cocker spaniel)
I would choose the 4'6" diameter (clear walk space between pole and
rail is 2'0"). Is that OK?
What is most important: the clear walk space between pole and rail or
the ramp angle?
Any suggestions?

Thank you,
Chris