Ok, I need help….I am a experienced frammer and I think I have met my match. I was asked to build a spiral staircase and I need help on determining the radius on the the top-plate for the half wall. The stiar case has an inside radius of 36-1/2”. That is the size of the bottom plate but the top plate should be a bigger radius. Stair risers are 7-1/8” and treads are 10-3/4. What next?
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Replies
I don't know if this will help: Helix Calculator
For your stairs I "back calculated" your riser/tread ratio and came up with the following entries:
Radius = 36.5
Height = 152.0019422
Angle in plan = 360
The entry for the rise is for one 360° circuit of the spiral:
36.5 × 2 × pi × 7.125 ÷ 10.75 = 152.0019422
Any numbers there that help?
Edited 9/21/2005 5:28 pm ET by JoeBartok
Edited 9/22/2005 9:55 am ET by JoeBartok
Edited 9/23/2005 9:33 am ET by JoeBartok
Thank you,
I think this will help.
Two words: Call Stan!