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Stairs using an adjacent wall as guards - how big a gap?

N

nealderidder

Sawhorse
Joined
Dec 7, 2010
Messages
420
Location
Sacramento, CA
Consider an exterior stair in a three-sided alcove, meaning it is open on one long side. If one wants to use the adjacent walls as guards (which is typical on interior stairs) what code provision limits the gap between the stairs and the wall? Is it the max 4" opening? That is what is shown in the attached diagram. If that is code compliant it seems like a really bad idea. It would be so easy to step into that gap. Is there anything in the code stopping someone from building that?

Also, see diagram again, what would prevent one from installing the handrail as shown? It's the right height, size, shape, clear space around it. But this location would pull me closer to the wall and closer to the gap. Is there anything in the code limiting how far away, horizontally, from the edge of the stair/walkway the handrail can be?
 

Attachments

Not sure if this is IBC or IRC and that does change things.

There are 2 sides to the thought here,
  • is it an opening in the walking surface
  • or is it the end of the walking surface and the guard limits the space?
Depending on your choice of thought it changes the interp.
  • If the walking surface ends, and the wall is considered the guard, the opening could be
    • Less than 4" for IBC
    • or Less than 4.375" IRC
  • The flip side is to consider it an opening in the walking surface and therefore needs the gap to be a 1/2" or less.
The handrail is meaning less to the opening requirement determined in the lower area.

As to the code change for the handrail in 2024, it restricts the offset from the side edge to be not more than 6" offset away.

As to if this is a good design or function, depends on who you talk to, but IMO though it complies if less than 4" based on the current model codes, I would strongly suggest reducing the opening to 2" or less, best if none.
 
Yes, in the situation you've described the horizontal setback of the handrail away from the tread walking surface constitutes a type of recess. Since you are in Sacramento, I'm going to assume the project is in California.

California modified the 2010 ADAS 505.5 with the words in italics as follows:

Clearance between handrail gripping surfaces and adjacent surfaces shall be 11/2 inches (38 mm) minimum. Handrails may be located in a recess if the recess is 3 inches (76 mm) maximum deep and 18 inches (457 mm) minimum clear above the top of the handrail.​
​
California duplicated this same requirement for private housing in CBC 11A, and there is a similar illustration in CBC fig. 11A-6B(c) that helps explain the 3"max. recess concept:

1733945701674.png

So if 1.5" is the min. clearance, and 1.25" is the minimum handrail width, and 3" is the maximum recess, this implies that the maximum distance from the start of the recess (edge of tread) to the side face of the handrail is only 1/4".

1733945968772.png
​
 
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Not everything is addressed in the Building Codes. The gap between the tread and the wall is a hazard. While there might not be a specific code that would prevent it, common sense would. Think children and pets or your leg stuck between the wall and the step. Given the inherent danger that stairs pose, no gap is a good idea.

Screen Shot 2024-12-11 at 12.07.29 PM.png
 
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Yikes said:
Yes, in the situation you've described the horizontal setback of the handrail away from the tread walking surface constitutes a type of recess. Since you are in Sacramento, I'm going to assume the project is in California.

California modified the 2010 ADAS 505.5 with the words in italics as follows:

Clearance between handrail gripping surfaces and adjacent surfaces shall be 11/2 inches (38 mm) minimum. Handrails may be located in a recess if the recess is 3 inches (76 mm) maximum deep and 18 inches (457 mm) minimum clear above the top of the handrail.​
​
California duplicated this same requirement for private housing in CBC 11A, and there is a similar illustration in CBC fig. 11A-6B(c) that helps explain the 3"max. recess concept:

View attachment 14853

So if 1.5" is the min. clearance, and 1.25" is the minimum handrail width, and 3" is the maximum recess, this implies that the maximum distance from the start of the recess (edge of tread) to the side face of the handrail is only 1/4".

View attachment 14854
​
Click to expand...
I see what you're saying but it seems like a stretch to correlate the recess requirements with a non-existent horizontal offset maximum. The recess dimensions are all about comfortably fitting your hand into that slot and grasping the handrail. Sounds like tbz is saying the offset is addressed in 2024, which is great.
 
nealderidder said:
I see what you're saying but it seems like a stretch to correlate the recess requirements with a non-existent horizontal offset maximum. The recess dimensions are all about comfortably fitting your hand into that slot and grasping the handrail. Sounds like tbz is saying the offset is addressed in 2024, which is great.
Click to expand...
If it was only about hand comfort, there would have been no need to limit the back wall of the recess to 3" maximum depth from the walking surface.
The only reason I can see for specifying maximum3" recess depth in conjunction with a minimum 1.5" handrail clearance is to push the handrail close to the tread.
 
Yikes said:
If it was only about hand comfort, there would have been no need to limit the back wall of the recess to 3" maximum depth from the walking surface.
The only reason I can see for specifying maximum3" recess depth in conjunction with a minimum 1.5" handrail clearance is to push the handrail close to the tread.
Click to expand...
Agreed that it's really the only thing to refer to in the code but who's to say that left edge of the 3" dimension is the edge of the walking surface? It's not explicit. You noted yourself it was "implied" and needed some math to figure out. Apparently 2024 is going to put a 6" offset limit on the handrail which is quite a bit more than the 3" recess would allow. I've run into this before with something like this on an exterior ramp: handrail-setback.JPG
 
Further info where this has been discussed before:

J

Thread 'Space between stair treads and sidewall'

Hi all,
Looking for some opinions here. I believe the code is silent to this. IRC 2018.

Let's say we have an interior stairway with a stone wall next to it. The architect doesn't want a guard rail or handrail on the stone wall side. The stair is "floating" so that it has a gap or 3" or 4" to the stone next to it. Another way of saying it is that there is 3" - 4" of space to the side of the treads, between the tread and wall.

What is an acceptable amount of gap allowed beside the tread without a guard? 1" seems fine. No one is getting a foot down a 1" gap. But how/where can this...
 
BN4537 said:
Further info where this has been discussed before:

J

Thread 'Space between stair treads and sidewall'

Hi all,
Looking for some opinions here. I believe the code is silent to this. IRC 2018.

Let's say we have an interior stairway with a stone wall next to it. The architect doesn't want a guard rail or handrail on the stone wall side. The stair is "floating" so that it has a gap or 3" or 4" to the stone next to it. Another way of saying it is that there is 3" - 4" of space to the side of the treads, between the tread and wall.

What is an acceptable amount of gap allowed beside the tread without a guard? 1" seems fine. No one is getting a foot down a 1" gap. But how/where can this...
Click to expand...
So 12 years and 4 code cycles later and this still apparently needs clarification in the code...
 
nealderidder said:
Agreed that it's really the only thing to refer to in the code but who's to say that left edge of the 3" dimension is the edge of the walking surface? It's not explicit. You noted yourself it was "implied" and needed some math to figure out. Apparently 2024 is going to put a 6" offset limit on the handrail which is quite a bit more than the 3" recess would allow. I've run into this before with something like this on an exterior ramp: View attachment 14858
Click to expand...
I've seen this detail before too, often at public transit stairways where the stairs are washed down and the channel functions as a type of canal to direct the water away from the steps. In that scenario, the handrail often projects outward to align or project into the tread space.
1733956895945.png
Regarding your detail, I have seen at least one situation a CASP cited it as a noncompliant barrier.
505.1 Says "handrails shall be provided alongside...". The word "alongside" is doing a lot of work, as it is reasonable to interpret that "alongside" means immediately adjacent.
Of course, there are other potential interpretations, but if your goal is to avoid gray areas that may tempt someone to sue, then it may be best practice to not horizontally separate the handrail from the treads with a miniature moat.
 
(2024 Model IBC) 1014.3 Lateral Location (New Specification) 6" maximum offset laterally

https://codes.iccsafe.org/content/IBC2024P1/chapter-10-means-of-egress#IBC2024P1_Ch10_Sec1014.3

If this is part of the accessible route, there are many AHJ that interpret this as an opening in the walking surface and limit to 1/2" maximum, otherwise if you determine the walking surface ends the code dictates shall not pass a 4-inch sphere for the guard opening.

To leave a gap of this size between the stair flight treads, landing walking surface and an adjacent wall determined to be serving as the guard, I would not recommend it. Just not sure how you not allow it per code.
 
I would consider the stair treads to be walking surfaces and limit any openings (gaps) to 1/2 inch as set forth in ICC/ANSI A117.1 section 302.3.

Basically, a gap at the side of a stair tread is a potential ankle breaker.
 
The Landing is a walking surface, a landing is a platform....
According to ADA standards, a "walking surface edge" shall be equipped with a detectable warning or guard, at the edge of a platform or walkway...,
 
You could try to use this based on intent....ANSI generally should not be in play on a stair as it is neither a route or accessible MOE....:

1011.7.1​

The walking surface of treads and landings of a stairway shall not be sloped steeper than one unit vertical in 48 units horizontal (2-percent slope) in any direction. Stairway treads and landings shall have a solid surface. Finish floor surfaces shall be securely attached.
 
steveray said:
ANSI generally should not be in play on a stair as it is neither a route or accessible MOE...
Click to expand...


1009.2 Continuity and components.
Each required accessible means of egress shall be continuous to a public way and shall consist of one or more of the following components:

1. Accessible routes complying with Section 1104.

2. Interior exit stairways complying with Sections 1009.3 and 1023.

3. Exit access stairways complying with Sections 1009.3 and 1019.3 or 1019.4.

4. Exterior exit stairways complying with Sections 1009.3 and 1027 and serving levels other than the level of exit discharge.
 
mtlogcabin said:
1009.2 Continuity and components.
Each required accessible means of egress shall be continuous to a public way and shall consist of one or more of the following components:

1. Accessible routes complying with Section 1104.

2. Interior exit stairways complying with Sections 1009.3 and 1023.

3. Exit access stairways complying with Sections 1009.3 and 1019.3 or 1019.4.

4. Exterior exit stairways complying with Sections 1009.3 and 1027 and serving levels other than the level of exit discharge.
Click to expand...
Yes, which abandons them on the landings....Hence my use of stair and not stairway.....
 
tbz said:
Just not sure how you not allow it per code.
Click to expand...
In as much as I never include code sections it would be just another correction on a correction slip. Most likely one of several on that correction slip. If asked about it I would point out the hazard. There's something about the way I go about it that people seldom ask for a code section and it's seldom that I write a correction that I can't back up with a code section. To be honest about this, I would not hesitate to write the correction with the conviction that Shirley there's a code for this situation.... and if not there should be.

What stands out about things like the gap is that anyone would advocate to keep it.
 
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