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Los Angeles CA - Single Family Curved Residential Stairs

Discussion in 'Residential Building Codes' started by Remington, Jun 13, 2018.

  1. Remington

    Remington Member

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    I am designing a curved staircase with a thread depth of 6" at it's smallest point and 11" , 12 inches away from the edge of the 6" edge.

    For Group R-1 occupancy, a Single Family home, do the curved stairs have to meet the curved stairs code requirement as specified below? It seems ridiculously difficult to comply in a small entry space.

    Curved stairways with winder treads must meet the minimum and maximum tread and riser requirements per Section 1009.4. Specifically, a minimum 11 inch tread depth, measured at a right angle to the tread's leading edge at a point 12 inches in from the side where the treads are narrower, is required; a minimum tread depth of 10 inches is required; and riser heights shall be 4 inches minimum and 7 inches maximum. Also, the smallest radius of the stair shall not be less than twice the required width of the stairway (radius requirements need not be met within Group R-3 occupancy or an individual dwelling unit within Group R-2 occupancy).
     
  2. mark handler

    mark handler Sawhorse

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    Group R-1 occupancy, a Single Family home?
    Is it a R-1 zoning designation? Or A R-1 Group per the Building code?
    Single Family home per the State code is an R-3 and under the Residential code not the building code.
     
    my250r11 likes this.
  3. Remington

    Remington Member

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    This is an R-1 zoning designation.
     
  4. Remington

    Remington Member

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    The single family home is in R1 zoning
     
  5. mark handler

    mark handler Sawhorse

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    Zoning has nothing to do with the building codes
    In CA you are under the Residential Building Codes
     
  6. Remington

    Remington Member

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    yes. I know. But can a curved stair with 6" min be allowed in a single family home?
     
  7. mark handler

    mark handler Sawhorse

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  8. Pcinspector1

    Pcinspector1 Platinum Member

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    Not on CA code but:

    2012 IBC 1009.12 Spiral stairways- shall have a 7.5-inches minimum clear tread depth at a point 12-inches from the narrow edge. Riser height shall not be more than 9.5-inches.

    RESIDENTIAL, 2012 IRC R311.7.10.1 Spiral stairways- 7.5-inch minimum tread depth @ 12-inches from the narrower edge. All treads to be identical and rise to be no higher than 9.5-inches.

    Both require a minimum of 26-inches clear width above and below the handrail. Head room can be 78-inches.

    Sooo... at the narrow end, 6-inches is too small

    That's what she said!
     
  9. Pcinspector1

    Pcinspector1 Platinum Member

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    I did't know this was referencing winder treads, R311.7.5.2.1, 6-inches is allowed at any point within the clear width of the stairs. Poster said curved stair, my mistake.

    Nice reference, MH
     

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