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I am having my stairs rebuilt and was wondering what the most common stair nosing length is. I have seen code requires nosing overhang be no more than 1.25". Is 1.25" common? Or is 1" more common?

Another question I have is I have seen the most common tread depth is 11". Does that include the nosing overhang?

I would love to hear the tread depth, and nosing length that any builders like to use.

  • Yes, tread depth includes nosing overhang. There is also a proportion from tread to riser. For me, the most common is 7” riser and 11” tread. As the riser decreases, the tread should increase for a “comfortable” use. That’s why the steps in front of the Washington Monument has 20” treads and 3” risers. Here’s a website that can help: knowledge.autodesk.com/support/revit-products/learn-explore/… – Lee Sam Mar 30 at 20:19
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I doubt any of us can provide actual statistics. You'll get personal preference and opinion. Mine is to shoot for 1-1/8", knowing that cutting stair stringers takes precision and still results in a bit of variation after all is said and done.

Tread depth does include the nosing. "Run" is the term for each step's dimension from riser to riser. "Rise" is the dimension from tread to tread.

______________________    __ 
______________________)    ^
                   ||      |
                   ||      |
                   ||      | rise
                   ||      |
                   _______________________
                   _______________________)
                                       ||
                    |
                    |<--- run ---------->
  • Very cool ASCII graphic 👍🏻 – Quoc Vu Apr 20 at 5:51
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The Code restricts the nosing to a maximum of 1 1/4” beyond the riser below. (See ICC 1009.7.5.1) and they shall all be uniform.

Also, the radius of the curvature of the nosing shall not exceed 9/16” and they all shall be uniform.

However, for ADA, no nosing is allowed because it’s considered a tripping hazard.

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