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Death by Stairwell

Discussion in 'Industry News' started by jar546, Jun 28, 2020.

  1. jar546

    jar546 *****istrator

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    I enjoyed this history lesson:

     
  2. cda

    cda Sawhorse

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    Very interesting

    And someone built a stair rise run, testing machine!
     
  3. ICE

    ICE Moderator

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    The video on electricity was shocking.
     
  4. Glenn

    Glenn Corporate Supporter
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    I've been sharing the new york subway video for quite some time. This one was also interesting. Thanks.
     
  5. e hilton

    e hilton Bronze Member

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    Very interesting about the subway stairs. Wish they had said what the difference is with the odd step.
     
  6. e hilton

    e hilton Bronze Member

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    Ok, i did a little research on the subway steps. Turns out the difference was 1/2” and it was corrected in 2012 right after the video was published. No idea how long it had been that way.
     
  7. e hilton

    e hilton Bronze Member

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    Question for the experts ...

    what is the allowable variation in riser height? I had thought it was no more than 1/4” between adjacent treads, and no more the 3/8” total for the run.
     
  8. Ty J.

    Ty J. Sawhorse

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    R311.7.5.1 Risers
    The riser height shall be not more than 73/4 inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Risers shall be vertical or sloped from the underside of the nosing of the tread above at an angle not more than 30 degrees (0.51 rad) from the vertical. Open risers are permitted provided that the openings located more than 30 inches (762 mm), as measured vertically, to the floor or grade below do not permit the passage of a 4-inch-diameter (102 mm) sphere.

    Exceptions:
    1. The opening between adjacent treads is not limited on spiral stairways.
    2. The riser height of spiral stairways shall be in accordance with Section R311.7.10.1.

    R311.7.5.2 Treads
    The tread depth shall be not less than 10 inches (254 mm). 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.
    The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).

    R311.7.5.2.1 Winder Treads
    Winder treads shall have a tread depth of not less than 10 inches (254 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline. Winder treads shall have a tread depth of not less than 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and do not have to be within 3/8 inch (9.5 mm) of the rectangular tread depth.

    Exception: The tread depth at spiral stairways shall be in accordance with Section R311.7.10.1.
     
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  9. Glenn

    Glenn Corporate Supporter
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    Has anyone else noticed how the IRC only requires uniformity of riser height and tread depth in each single flight of stairs (can change after a landing). However, the section for nosing projection uniformity(R311.7.5.3) states the requirement is for "stairways" (includes all flights on both sides of an intermediate landing).

    I have already prepared a modification proposal for the 2024 IRC to change the nosing uniformity to "flight of stairs". After a landing, your cadence of step can restart so rise/run can change. I can't think of a reason the nosing projections couldn't change too. If you agree, please support this code change when you see it. If you don't agree, then be a teacher and share with us why. Thanks.
     
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  10. ADAguy

    ADAguy Registered User

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    Consider the potential change in handrail height that may occur at the changes in flights you proposal? If risers differ in height at each one then the handrail may develop waves if measured at each tread vs being consistent.
     
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  11. TheCommish

    TheCommish Sawhorse

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    A few Mass Editions ago the difference between rise and run of adjacent tread way limited to 3/16 of an inch, when we adopted the 2003 IBC the dimension changed to 3/8 overall tolerance.

    I think 3/16 between stairs should be the max and 3/8 over if flight then not 3/8 between adjacent treads

    underline eddited
     
    #11 TheCommish, Jul 6, 2020
    Last edited: Jul 6, 2020
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  12. ADAguy

    ADAguy Registered User

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    So, as to measuring handrail height?
     
  13. Paul Sweet

    Paul Sweet Sawhorse

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    R311.7.8.1 requires handrail height to be between 34" and 38". It doesn't require the exact same height at each and every step. I doubt that anybody would notice 3/16" difference between adjacent steps.

    Come to think of it, a handrail that started at 34" above the first riser and increased to 38" above the last riser might comply!
     
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  14. ADAguy

    ADAguy Registered User

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    Not a chance! We disapproved one for that very reason, inconsistent height along its length.
     
  15. steveray

    steveray Sawhorse

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    Don't think there is a code section for that...What if I step on a different part of the tread?

    You have my support on the nosings Glenn!
     
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  16. TheCommish

    TheCommish Sawhorse

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    A handrail needs to be uniform height of the nosing line of the treads
     
  17. ADAguy

    ADAguy Registered User

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    And what if the heights differ within allowed maximums between risers?
    Handrail can still be considered uniformly compliant?
     
  18. TheCommish

    TheCommish Sawhorse

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    First, on inspections I try not to take the tape measure out of the truck. I have been doing this long enough that in most cases, looking, walking the stair and grasping the rails will tell me if there are compliance issues.

    If you wan to check for uniformity of star rise -run look from the top of the stair down the plane of nosing, if you can get on line and see all the tip of the nosing the stair is uniform, handrails have a comfortable height in the allowed range .

    Most often if the stair if it is out of compliance is real sloppy or it is the top or bottom tread that is out of compliance with the uniformity.

    our building permit cards are 8.5 x 11 inches, a paper bill is 6 inches.

    If I observe a condition that I feel is out of compliance or real close then the tape comes out. I do not expect machinist tolerance of wood the swells and shrinks.

    some days I don't even have to get out of the truck photo for letter.jpg
     
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  19. Glenn

    Glenn Corporate Supporter
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    In the IBC the handrail height has to be uniform.

    In the IRC it does not.

    I don't understand how a lack of uniform height is going to make me loose my grasp? When I use stairs, my hand is moving in relation to my body, as my body is bobbing up and down with each step.
     
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  20. Rick18071

    Rick18071 Sawhorse

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    I usually only use the tape measure for accessibility.
     

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