Circular stair? Help with CBC R311.7.3 needed

[Jonathan]

Hello, Am doing an exterior stair which serves the garage and entry levels of a residence in ca.It's a continuous winder or circular stair - see pdf plan attached.I would like to have 4" risers and a 16" tread (tread shown of diagram is a little less) and would like for someone to let me know if I am implementing the code correctly.I have included the dimensions and locations on the stair drawing provided. Tread depth measered perpendicular to leading edge to next vertical riser and 12 inches from the side where the winders are narrower. Do I have this "walkline" correct on the drawing?Best to all,Jonathan

View attachment 1790

code stair detail 11 x 17.pdf

code stair detail 11 x 17.pdf

 

[fatboy]

It appears to me you have it correctly, my answer is from the unamended IRC though.

 

[mark handler]

That is a winding not Circular stair.

The code identifies winding and spiral stairs, not Circular stairs

FYI

http://www.abqstair.com/wp-content/uploads/2012/06/SMAVisualInterpretationIRC2009ecopy_1__1_.pdf

 

[Jonathan]

Their figure 13 shows a tread depth measurement method different from the code "at a right angle to the tread's leading edge"

CBC R311.7.4.2 reads:

The minimum tread depth shall be 10 inches. The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge....

Looks like they are measuring the arc at 12" in from the inside radius

or perpendicular to a line bisecting the angle between risers?

That is a winding not Circular stair.The code identifies winding and spiral stairs, not Circular stairs

FYI

http://www.abqstair.com/wp-content/uploads/2012/06/SMAVisualInterpretationIRC2009ecopy_1__1_.pdf

 

[Jonathan]

Thank you for helping!

That is a winding not Circular stair.The code identifies winding and spiral stairs, not Circular stairs

FYI

http://www.abqstair.com/wp-content/uploads/2012/06/SMAVisualInterpretationIRC2009ecopy_1__1_.pdf

 

[Jonathan]

Sorry everyone I should have cited CRC instead of CBC in my code references!!

 

[mark handler]

Sorry everyone I should have cited CRC instead of CBC in my code references!!

Don't need to shout

 

[demsley]

I think it's ok with drawing and code is looking ok but who make this drawing. You made this by a architect or you consulted with someone.

 

[demsley]

I think it's ok with drawing and code is looking ok but who make this drawing. You made this by a architect or you consulted with someone.

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