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A way to make a 42" spiral work rather than 60"?

SJP415

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Jun 15, 2017
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11
Location
San Francisco
Hello - we are adding a second story above our single-car garage. The lot is very tiny and we have a very tight building envelope due to setbacks and other requirements. The garage and the new space above it will become one living unit for a total of 302sf. We had it designed with a 42" diam. spiral stair, but under the CA Residential Building Code it says a 60" diam. is required for a spiral stair. We're wondering is there any way possible we can have the smaller spiral be allowed, maybe with how/what we call the space the spiral is accessing? The space being added above is just going to be an open loft space for a desk or a bed, etc. No closet up there or bath, etc. The space below (the former garage space) will have a small bath and kitchenette. Any help on how to make this smaller spiral work and/or another solution would be greatly appreciated. Thank you so much.
 
Can you post a link to where you see the 60 inch

This is not from the calif code::


R311.7.10Special stairways.
Spiral stairways and bulkhead enclosure stairways shall comply with the requirements of Section R311.7except as specified in Sections R311.7.10.1 and R311.7.10.2.

R311.7.10.1Spiral stairways.
The clear width at and below the handrails at spiral stairways shall be not less than 26 inches (660 mm) and the walkline radius shall be not greater than 241/2inches (622 mm). Each tread shall have a depth of not less than 63/4 inches (171 mm) at the walkline. Treads shall be identical, and the rise shall be not more than 91/2 inches (241 mm). Headroom shall be not less than 6 feet 6 inches (1982 mm).
 
I was told that that the 26" is just the clear width - after you add the pole and the handrails you need to plan on 5' diam. for clear space...
 
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I had heard there may be some exception in the building code that would allow for a deviation in the code if the spiral stair was used to access 200sf or less and did not have a primary bathroom or kitchen...
 
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