Handrail and Guardrail Projections at Intermediate Landings (Open/Drop-Off Side)

[ambe]

At intermediate landings in U-shape (180° switchback) stairs, what are the CBC/IBC requirements for handrails and guardrail posts located on the open/drop-off side (not the wall side)? Specifically, how much are they allowed to project or intrude into the clear landing space without reducing the minimum landing depth that must be maintained for safe passage and code compliance (1011.2 and 1011.6)?

Please see the attchment.

 

[arwat23]

Handrail: 4.5" on each side (CBC 1014.8)
"Projections into the required width of aisles, stairways and ramps at each side shall not exceed 4 1/2 inches (114 mm) at or below the handrail height."

Guardrail: 0"
Cannot project into required clear width.

 

[RLGA]

Handrail: 4.5" on each side (CBC 1014.8)
"Projections into the required width of aisles, stairways and ramps at each side shall not exceed 4 1/2 inches (114 mm) at or below the handrail height."

Guardrail: 0"
Cannot project into required clear width.

Egress width is measured above the handrail (IBC Section 101.4.8), so the face of a guard below a handrail can project up to 4-1/2" inches into the required width, as long as it allows the required graspability of the handrail.

 

[arwat23]

Egress width is measured above the handrail (IBC Section 101.4.8), so the face of a guard below a handrail can project up to 4-1/2" inches into the required width, as long as it allows the required graspability of the handrail.

IBC 1014 is specific to handrails though, not guardrails. Guards (IBC / CBC 1015) doesn't have this language.

 

[Yankee Chronicler]

Egress width is measured above the handrail (IBC Section 101.4.8), so the face of a guard below a handrail can project up to 4-1/2" inches into the required width, as long as it allows the required graspability of the handrail.

That's for walking egress width, based on the fact that the shoulders are typically the widest part of the average human body. For ramps and accessible egress stairs, I don't think guards can project into the required width. I know people aren't going to drive a wheelchair down a stair, but accessible means of egress stairs are sized to allow firefighters to transport a wheelchair down the stairway.

 

[RLGA]

IBC 1014 is specific to handrails though, not guardrails. Guards (IBC / CBC 1015) doesn't have this language.

Correct, but the reading of 1014.8 states projections "shall not exceed 4-1/2" at or below the handrail height." Thus, the handrail can sit on top of a wall acting as part* of the stairway's guard.

*I say "part" because the handrail height is lower than the required guard height, excluding those exceptions that permit a lower guard height.

 

[ambe]

Handrail: 4.5" on each side (CBC 1014.8)
"Projections into the required width of aisles, stairways and ramps at each side shall not exceed 4 1/2 inches (114 mm) at or below the handrail height."

Guardrail: 0"
Cannot project into required

 

[ambe]

Very interesting — according to your response, it seems the EOR made a mistake regarding the minimum clear space at the stair landing, and I think this could be a major issue in the design of this commercial project.

 

[arwat23]

Correct, but the reading of 1014.8 states projections "shall not exceed 4-1/2" at or below the handrail height." Thus, the handrail can sit on top of a wall acting as part* of the stairway's guard.

*I say "part" because the handrail height is lower than the required guard height, excluding those exceptions that permit a lower guard height.

Just to make sure I understand correctly, you can have effectively a 9" narrower staircase as long as those 4.5" projections on each side are below the handrail? Using your example of a wall with a handrail on top of it, I could have a wall reduce the clear width at and below the handrail a theoretical 27" (36" minimum required clear width using 1011.2 ex 1, subtracting 4.5" each side)?

 

[RLGA]

Just to make sure I understand correctly, you can have effectively a 9" narrower staircase as long as those 4.5" projections on each side are below the handrail? Using your example of a wall with a handrail on top of it, I could have a wall reduce the clear width at and below the handrail a theoretical 27" (36" minimum required clear width using 1011.2 ex 1, subtracting 4.5" each side)?

Correct. The required handrail height places the handrail at the average height of a person's waist. Most people are wider above the waist than they are below the waist. About 9% of the U.S. population is considered extremely obese, and I would assume a much smaller percentage would have body measurements where the waist is much wider than the shoulders. Thus, it is assumed that up to 4-1/2 inches of a person's overall width extends over the handrail so that the arm is located directly above the handrail.

 

[arwat23]

Very interesting — according to your response, it seems the EOR made a mistake regarding the minimum clear space at the stair landing, and I think this could be a major issue in the design of this commercial project.

That, or the contractor or fabricator made a mistake. Based off the one photo (kinda hard to tell, not a wide enough angle to know for sure), it looks like that landing is a choke point and gets really narrow due to the rails. Definitely looks like it doesn't meet code.

 

[RLGA]

Per Section 1011.6, the width of a landing, perpendicular to the direction of travel, cannot be less than the width of the stairs. It's hard to tell from the photo, but it appears that the width is less than the width of the stairway.

 

[bill1952]

I've always wondered how the capacity of stairs and level walking surfaces.played into this. A 44" stair has a capacity of 146 at .3"; 44" level 220 at .2.; or conversely 29.2" should accommodate the 146.

 

[ambe]

Per Section 1011.6, the width of a landing, perpendicular to the direction of travel, cannot be less than the width of the stairs. It's hard to tell from the photo, but it appears that the width is less than the width of the stairway.

View attachment 16340

Per Section 1011.6, the width of a landing, perpendicular to the direction of travel, cannot be less than the width of the stairs. It's hard to tell from the photo, but it appears that the width is less than the width of the stairway.

Please see photos

 

[arwat23]

Please see photos

It looks like there was a few mistakes when designing or constructing those stairs. I've never seen a stair landing with that shape before, at least not that extreme.

For example, why are the first riser on each side so far apart? It looks like they tried to add the handrail extensions normally required by CBC 11B-505.10 at the top and bottom of some of those landings (especially the last two photos) for the inside turn rail, which you don't need to do at a landing like this.

This is all speculation on my part, so take the heftiest grain of salt with my crackpot theories.

 

[TheCommish]

Looks bad and seems the landing width is reduce

 

[tbz]

Without seeing the entire layout of the floor to floor with elevation it is hard to figure out why this mid landing is so off.

But here are a few notes:
The detailer that did this was most-likely contracted from overseas and was told to use radius bends for all the handrail flows and not miters. This leads to extended distances between changes in direction so the "Pipe/Tubing" bending machines die clamps can grab the material and bend without having to weld.

• This likely lead to the guard section extending past the posts to accommodate the fabrication style used.
  • As noted by all commenting "bad choice on fabrication and if the shop drawings where submitted to the EOR before fabrication and installation they should have redlined it.
• As to the large distance between riser/nosing offsets, this is common place in many locations when working with none equal stair flights.
  • Yes the most common practice is for switchback flights is to split the height and install (2) same riser flights.
  • We are seeing more of an change with offset story height differences starting to work into this common oversize offset.
    • Example would be a 3-story building with a 16ft floor to floor from ground level (1st fl) to the 2nd floor and a 12ft floor to floor from the 2nd floor to the 3rd floor.
    • The first (3) flights from ground level up are all the same height, number of equal risers) and the 4th flight after the upper mid-landing is slide over to match the remaining riser heights.
      • Not saying this is the case here, but it was more common in the past to keep the mid-landing side the same and extend the 3rd floor landing area, but for some reason designers are flipping this more and more. My guess is it has to do something with the pockets for the headers.
• The distance between the face of the guard and the wall at the mid-landing crossover is smaller than between the flights and the wall & guard, how much is unknow without the measurements.
• The real question to this issue is if they even have the room, pending on the header location holding up the mid-landing to obtain the distance to match.
  • The simplest way to figure that out is to measure from the wall out at the floor to the point where the guard above needs to be.
  • If that point is 4-1/2" or less from the 180 turn in the stringers endpoint, then Cut to guard back to that point and pull the handrail back to fit the matched dimensions.
  • If the stringer is still raised in the minimum landing surface and is placed there to hit the header it is sitting on below, then an easy fix is not in the cards.
• On another note, I believe in the current CBC 1014.8 is the 1-1/2" minimum clearance from the wall and 1014.9 is the projection section with the 4-1/2" maximum.

 

[steveray]

They didn't need the extensions there and that is part of the problem...

 

[Yikes]

The photo shows inner handrail extensions that are so long that this construction can qualify as two separate (discontinuous) flights of stairs, in which case the areas that meet the definition of "stair landing" are shown in blue.
In that scenario, the yellow area is technically not a landing for either stair flight - -it is between two landings. Therefore the required width "Y" for the yellow area is based on occupant load calculations, and is not governed by the "landing length = stair width" of 1011.6.

 

[bill1952]

Yeah. That's what I was talking about. Basically needs to be 2/3 of stair width for equal capacity.

 

[Yikes]

Yeah. That's what I was talking about. Basically needs to be 2/3 of stair width for equal capacity.

I agree, sand we also need to consider that 1005.2 refers us to other sections of the code besides the occupancy calc for minimum widths.
Would it be reasonable to extrapolate from 1020.3 that an occupant load on the stair between 1-49 needs min. 36" walking surface width?

 

[bill1952]

I agree, sand we also need to consider that 1005.2 refers us to other sections of the code besides the occupancy calc for minimum widths.
Would it be reasonable to extrapolate from 1020.3 that an occupant load on the stair between 1-49 needs min. 36" walking surface width?

I'd say so, especially with 1011.2 Exception 1. Out of my area of practice but that's the total occupant load regardless of the number of stairs, correct? 98 occupants and stairs are minimum 44" regardless of how many stairs?