Regarding stairway code, I understand the distance between the handrail and the opposite wall can be a minimum of 31.5". But I can't find any wording on when the handrail is attached to posts. Does this distance apply the same way when the rail is on posts?

Specifically I want to know if the distance from the outer edge of the posts to the opposite wall is 33.75", is that ok?

Please see the drawing to understand what I'm talking about. enter image description here

  • 1: Residential - or Commercial? 2- A drawing to know exactly what you are talking about. 3: This answer is based on assumptions residential and wall along the stairs parallel with the rail. 36 Inches is what I would expect is required. However I will post my answer.
    – Ken
    Mar 13 '18 at 8:40
  • I think the question is rendered moot by the requirement that you have continuous grippable handrail, which would be the furthest inside point in the system. The post positions don't matter then.
    – isherwood
    Mar 13 '18 at 20:40

This answer depends on where you are in the world and if you are in the USA what state you live in.

Section R311.7.1 IRC 2009:

Stairways shall not be less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. Handrails shall not project more than 4.5 inches (114 mm) on either side of the
stairway and the minimum clear width of the stairway at and below the handrail height, including treads and landings, shall not be less than 31.5 inches (787 mm) where a handrail is installed on one side and 27 (698 mm) where handrails are provided on both sides. Exception: The width of spiral stairways shall be in accordance with Section R311.5.8.

Above snippet from: http://www.co.stevens.wa.us/landservices/documents/STAIRWAYSECTION.pdf


The 2017 edition of the IRC is the same as Ken noted in the 2009 edition.

So, No, 33.75” from the face of the railing post to the opposite wall is not acceptable. It must be 36” wide. (See ICC Section R311.7.1, 2017 edition.)

  • So the rule regarding handrails that says there must be a minimum of 31.5" from the handrail to the wall does not apply to a handrail attached to posts and balusters? Can you explain?
    – Mike L
    Mar 14 '18 at 1:17
  • @MikeL I think the 31.5” measurement applies, but it’s a MINIMUM. So while you meet that requirement, you must also meet the 36” MINIMUM requirement too.
    – Lee Sam
    Mar 14 '18 at 2:01

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