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CH 10: Means of Egress - Stairway Width discrepancy / confusion

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peri_5xg

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Can someone help me out with this. I am trying to see what the difference is between two parts of this chapter which references minimum stairway widths. In section 1011: Stairways, Subsection 1011.2 Width and Occupancy it says "minimum width shall not be less than 44 inches"

In section 100.9: Accessible Means of Egress and Subsection 1009.3.2. it says "Stairways shall have a clear width of 48" between handrails.

Why is there a discrepancy, or am I misinterpreting something? I am trying to design egress stairs correctly.
 
A standard stairway is required to be a minimum of 44 inches (not clear width, but above the handrails). If a stair is used as one of the required accessible means of egress (not all stairs are), then you must provide the 48 inches of clear width between the handrails if the building is not sprinklered or the stairs are not accessed through a refuge area associated with a horizontal exit; otherwise, the 44-inch minimum width is the default.
 
As Ron said, not all stairs are an accessible means of egress. The exceptions Ron are referring to are provided in red below.

1011.2 Width and Capacity
The required capacity of stairways shall be determined as specified in Section 1005.1, but the minimum width shall be not less than 44 inches (1118 mm). See Section 1009.3 for accessible means of egress stairways.
Exceptions:
  1. Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches (914 mm).
  2. Spiral stairways as provided for in Section 1011.10.
  3. Where an incline platform lift or stairway chairlift is installed on stairways serving occupancies in Group R-3, or within dwelling units in occupancies in Group R-2, a clear passage width not less than 20 inches (508 mm) shall be provided. Where the seat and platform can be folded when not in use, the distance shall be measured from the folded position.
1009.3 Stairways
In order to be considered part of an accessible means of egress, a stairway between stories shall have a clear width of 48 inches (1219 mm) minimum between handrails and shall either incorporate an area of refuge within an enlarged floor-level landing or shall be accessed from an area of refuge complying with Section 1009.6. Exit access stairways that connect levels in the same story are not permitted as part of an accessible means of egress.
Exceptions:
  1. Exit access stairways providing means of egress from mezzanines are permitted as part of an accessible means of egress.
  2. The clear width of 48 inches (1219 mm) between handrails is not required in buildings equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2.
  3. The clear width of 48 inches (1219 mm) between handrails is not required for stairways accessed from a refuge area in conjunction with a horizontal exit.
  4. Areas of refuge are not required at exit access stairways where two-way communication is provided at the elevator landing in accordance with Section 1009.8.
  5. Areas of refuge are not required at stairways in buildings equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2.
  6. Areas of refuge are not required at stairways serving open parking garages.
  7. Areas of refuge are not required for smoke-protected assembly seating areas complying with Section 1029.6.2.
  8. Areas of refuge are not required at stairways in Group R-2 occupancies.
  9. Areas of refuge are not required for stairways accessed from a refuge area in conjunction with a horizontal exit.
 
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I believe the 48" clear between handrails is to allow a few people to carry a person in a wheelchair down the stairs (or use an evacuation chair) from an area of refuge in case the elevator was out of service.
 
ADAguy said:
Now explain to me why residential stairs only require a handrail on one side?
Click to expand...
The occupants are very familiar with their surroundings, the occupant load is quite low, and it is very unlikely that emergency responders will be climbing the stairs as occupants are coming down.

And, just to be clear, it only applies to stairways within residential dwelling units and not any stairway serving a residential occupancy.
 
Hello everybody, I am new to the forum although I wanted to join for a while. I have a question regarding the stair width calculation I hope you may answer or help with. These are the project specs:

Location: Omaha NE (IBC 2018 adopted code)
Number of stories: ground level + second story.
Occupancy: B (Concentrated Business)
Total occupant load at 2nd story: 42 people
Total bldg occupant load: 65
Construction Type: TYPE IIB Sprinklered w/ emergency visual & audio system.
Stairs: Two. One 48” wide; the other 36” wide. The larger stair is open and the egress is through the ground level lobby. The smaller stair is intended for employee use only and the egress door is only accessed from the interior of the bldg.
Elevator: Yes, intended to be accessible.

I was hoping that the smaller stair could be reduced to 36” per the exception:
  1. Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches (914 mm).
Also, the larger stair could be used as part of the accessible path of travel.

Thank you.

anybody could tell me how to upgrade the membership?
 
Got to your login name, upper right corner, click on it and the select "Account Upgrades", then select the plan you would like to use.

Welcome!
 
Feanor said:
Hello everybody, I am new to the forum although I wanted to join for a while. I have a question regarding the stair width calculation I hope you may answer or help with. These are the project specs:

Location: Omaha NE (IBC 2018 adopted code)
Number of stories: ground level + second story.
Occupancy: B (Concentrated Business)
Total occupant load at 2nd story: 42 people
Total bldg occupant load: 65
Construction Type: TYPE IIB Sprinklered w/ emergency visual & audio system.
Stairs: Two. One 48” wide; the other 36” wide. The larger stair is open and the egress is through the ground level lobby. The smaller stair is intended for employee use only and the egress door is only accessed from the interior of the bldg.
Elevator: Yes, intended to be accessible.

I was hoping that the smaller stair could be reduced to 36” per the exception:
  1. Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches (914 mm).
Also, the larger stair could be used as part of the accessible path of travel.

Thank you.

anybody could tell me how to upgrade the membership?
Click to expand...

your 2nd floor is required to have two means of egress and per section 1009.1 you are required two accessible means of egress from that floor. The 36" wide stair would not meat the AMOE requirement.
 
Feanor said:
Stairs: Two. One 48” wide; the other 36” wide. The larger stair is open and the egress is through the ground level lobby. The smaller stair is intended for employee use only and the egress door is only accessed from the interior of the bldg.
Elevator: Yes, intended to be accessible.

I was hoping that the smaller stair could be reduced to 36” per the exception:
  1. Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches (914 mm).
Click to expand...
I think your issue is this: 1011.2 exc. #1: "Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches"

With an upper floor occupant load of 65, and 2 stairs serving that occupant load, does the occupant load referred to in 1011.2 exc. #1 refer to:
  1. The occupant load of the entire floor? (65 occupants = need 2nd stair to be 44" min width)
  2. The # of occupants that are designed to exit on each stair? (65 occupants / 2 stairs = 33 occ. per stair = need 2nd stair to be 36" min width)
 
Back in BOCA days it was 50 occupants using the stair. I believe that at one time the IBC tightened it up to 50 occupants for the entire floor for a couple code cycles.

In Chapter 2 Occupant Load is defined as "The number of persons for which the means of egress of a building or portion thereof is designed." I would interpret this as the number of occupants using that stairway.
 
Feanor said:
Hello everybody, I am new to the forum although I wanted to join for a while. I have a question regarding the stair width calculation I hope you may answer or help with. These are the project specs:

Location: Omaha NE (IBC 2018 adopted code)
Number of stories: ground level + second story.
Occupancy: B (Concentrated Business)
Total occupant load at 2nd story: 42 people
Total bldg occupant load: 65
Construction Type: TYPE IIB Sprinklered w/ emergency visual & audio system.
Stairs: Two. One 48” wide; the other 36” wide. The larger stair is open and the egress is through the ground level lobby. The smaller stair is intended for employee use only and the egress door is only accessed from the interior of the bldg.
Elevator: Yes, intended to be accessible.

I was hoping that the smaller stair could be reduced to 36” per the exception:
  1. Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches (914 mm).
Also, the larger stair could be used as part of the accessible path of travel.

Thank you.

anybody could tell me how to upgrade the membership?
Click to expand...
Look at TABLE 1006.3.3(2)
Your stair needs full compliance.
 
Yikes said:
Mark, Feanor already established the floor plan is providing TWO stairs, which is what Table 1006.3(2) addresses.
Click to expand...

just repeating what I previously stated in post #15 above

your 2nd floor is required to have two means of egress and per section 1009.1 you are required two accessible means of egress from that floor. The 36" wide stair would not meet the AMOE requirement. Both stairs will need to be 44" min.
 
  1. The clear width of 48 inches (1219 mm) between handrails is not required in buildings equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2.
So what is required?
 
Tim Mailloux said:
just repeating what I previously stated in post #15 above

your 2nd floor is required to have two means of egress and per section 1009.1 you are required two accessible means of egress from that floor. The 36" wide stair would not meet the AMOE requirement. Both stairs will need to be 44" min.
Click to expand...
Repeating what Feanor said in post #12 above: One of the stairs is 48" which meets 1009.3.2, and 1009.1 only requires that "not less than one accessible means of egress", so the AMOE requirement is already covered for that floor level.
So, the only remaining question appears to be whether stair #2 needs to be 36" or 44" - - see posts #16 and 17.

Perhaps it would have been better / clearer if, instead of tagging onto peri_5xg's original post, Feanor had created a separate post in the Commercial Building Codes forum.
 
Last edited:
In the example by @Feanor the occupant load the stair serves is 42. Based on 2018 IBC 1004.2.3, the occupant loads from separate stories shall not be added.
 
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