In reviewing the plans for a proposed two-story building recently, I encountered an unusual aspect of the means of egress that many architects and many code officials are not aware of. We may not encounter it often, but it’s in the code so I thought this could be a “learning moment” for us all. This article attempts to put together the code references so we can all be on the same page.
The issue that came up is that one of the two stairs from the second floor is designated as “exit access” rather than as an “exit.” I expect that, like me, you are all probably accustomed to thinking that every story requires two exits. It turns out that’s true — but not exactly. The IBC actually requires that every story has access to the required number of exits, but the actual exit may be located one story above or below the story from which egress is being evaluated.
The following are the IBC code sections, along with the comments from the IBC Commentary:
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1006.3 Egress from stories or occupied roofs. The means of egress system serving any story or occupied roof shall be provided with the number of exits or access to exits based on the aggregate occupant load served in accordance with this section. The path of egress travel to an exit shall not pass through more than one adjacent story.
1007.1.1 Two exits or exit access doorways. Where two exits, exit access doorways, exit access stairways or ramps, or any combination thereof, are required from any portion of the exit access, they shall be placed a distance apart equal to not less than one-half of the length of the maximum overall diagonal dimension of the building or area to be served measured in a straight line between them. Interlocking or scissor stairways shall be counted as one exit stairway.
1007.1.1.1 Measurement point. The separation distance required in Section 1007.1.1 shall be measured in accordance with the following:
1. The separation distance to exit or exit access doorways shall be measured to any point along the width of the doorway.
2. The separation distance to exit access stairways shall be measured to the closest riser.
3. The separation distance to exit access ramps shall be measured to the start of the ramp run.
1007.1.3 Remoteness of exit access stairways or ramps. Where two exit access stairways or ramps provide the required means of egress to exits at another story, the required separation distance shall be maintained for all portions of such exit access stairways or ramps.
1017.3 Measurement. Exit access travel distance shall be measured from the most remote point within a story along the natural and unobstructed path of horizontal and vertical egress travel to the entrance to an exit.
1017.3.1 Exit access stairways and ramps. Travel distance on exit access stairways or ramps shall be included in the exit access travel distance measurement. The measurement along stairways shall be made on a plane parallel and tangent to the stair tread nosings in the center of the stair and landings. The measurement along ramps shall be made on the walking surface in the center of the ramp and landings.
1019.1 General. Exit access stairways and ramps serving as an exit access component in a means of egress system shall comply with the requirements of this section. The number of stories connected by exit access stairways and ramps shall include basements, but not mezzanines.
1019.2 All occupancies. Exit access stairways and ramps that serve floor levels within a single story are not required to be enclosed.
1019.3 Occupancies other than Groups I-2 and I-3. In other than Group I-2 and I-3 occupancies, floor openings containing exit access stairways or ramps that do not comply with one of the conditions listed in this section shall be enclosed with a shaft enclosure constructed in accordance with Section 713.
1. In buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1 with other than Group H or I occupancies, an exit access stairway serving an occupant load of less than 10 not more than one story above the level of exit discharge.
2. In Group R-1, R-2 or R-3 occupancies, exit access stairways and ramps connecting four stories or less serving and contained within a single residential dwelling unit or sleeping unit or live/work unit.
3. Exit access stairways serving and contained within a Group R-3 congregate residence or a Group R-4 facility are not required to be enclosed.
4. Exit access stairways connecting the first and second floors of Group R-1 bed-and-breakfast establishments. Stairways connecting the second and third floors in such occupancies shall be enclosed with fire separation assemblies having a fire-resistance rating of not less than 1 hour. Stairways connecting the basement and the first floor occupancies shall be enclosed with fire partitions having a fire-resistance rating of not less than 1/2 hour with 20-minute fire-resistance-rated door assemblies. Fire-resistance assemblies at stairways in Group R-1 bed-and-breakfast establishments shall not be required to be supported by fire-resistance-rated construction.
5. Exit access stairways and ramps within an atrium complying with the provisions of Section 404.
6. Exit access stairways and ramps in open parking garages that serve only the parking garage.
7. Exit access stairways and ramps serving open-air seating complying with the exit access travel distance requirements of Section 1029.7.
8. Exit access stairways and ramps serving the balcony, gallery or press box and the main assembly floor in occupancies such as theaters, places of religious worship, auditoriums and sport facilities.
9. Stairways serving outdoor facilities where all portions of the means of egress are essentially open to the outside.
10. Exit access stairways serving mezzanines complying with the provisions of Section 505.
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For what it’s worth, The NFPA 101 Life Safety Code Handbook also discusses using stairways as exit access rather than as exits.
There is arguably nothing in the building codes more important than Chapter 10: Means of Egress. If the purpose of the building code system is protection of public safety, health and welfare, it’s difficult to think of anything more critical than ensuring that occupants can escape from a building in the event of a fire or other catastrophe. Central to this is ensuring that each building, and each space within a building, has access to sufficient numbers of exits, with adequate exit capacity, and within the prescribed exit access travel limits.
The notion that a required egress stair on an upper story of a building does not have to be enclosed and protected as an exit initially seems to be almost a contradiction in terms. It is important to differentiate between a stair that serves as a required exit access path and as such is subject to several specific requirements, and a non-required communicating or “convenience” stair, which may certainly be used for exit access by occupants who are near it, but which is in addition to the minimum number and distribution of required means of egress in the building and is, therefore not subject to all the requirements that apply to exit access stairways. The major difference with an exit access stairway is that, unlike an enclosed exit stair where the exit access travel distance ends at the door leading into the stair, with an exit access stair the exit access travel distance measurement continues down along the stair and across the lower floor until it reaches either an enclosed exit, or an exit door that discharges directly to the exterior.
The issue that came up is that one of the two stairs from the second floor is designated as “exit access” rather than as an “exit.” I expect that, like me, you are all probably accustomed to thinking that every story requires two exits. It turns out that’s true — but not exactly. The IBC actually requires that every story has access to the required number of exits, but the actual exit may be located one story above or below the story from which egress is being evaluated.
The following are the IBC code sections, along with the comments from the IBC Commentary:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1006.3 Egress from stories or occupied roofs. The means of egress system serving any story or occupied roof shall be provided with the number of exits or access to exits based on the aggregate occupant load served in accordance with this section. The path of egress travel to an exit shall not pass through more than one adjacent story.
** Emergency evacuation from a multistory building will typically involve stairways or ramps as the vertical element for the means of egress route. The number of required ways off the story (via exit or exit access elements) is based on the occupant loads shown in Table 1006.3.1. These stairways and ramps must comply with the general provisions (Sections 1011 and 1012 respectively), and can be exit access (Section 1019) or exits (Section 1023 and 1027). When exit access stairways or ramps are part of that route, the measurement of the exit access travel distance will include travel from the most remote point. On the floor, to and down the exit access stairway or ramp and from the bottom of the stairway or ramp to an enclosure for an exit stairway or ramp or exterior door (see Section 1017.3). Vertical travel is slower than horizontal travel, so the exit access stairway or ramp in a building with two or more exits should not be used for more than one story before an exit is reached.
1007.1.1 Two exits or exit access doorways. Where two exits, exit access doorways, exit access stairways or ramps, or any combination thereof, are required from any portion of the exit access, they shall be placed a distance apart equal to not less than one-half of the length of the maximum overall diagonal dimension of the building or area to be served measured in a straight line between them. Interlocking or scissor stairways shall be counted as one exit stairway.
1007.1.1.1 Measurement point. The separation distance required in Section 1007.1.1 shall be measured in accordance with the following:
1. The separation distance to exit or exit access doorways shall be measured to any point along the width of the doorway.
2. The separation distance to exit access stairways shall be measured to the closest riser.
3. The separation distance to exit access ramps shall be measured to the start of the ramp run.
** Where exit access stairways are permitted to be unenclosed, the remoteness measurement for doorways shall begin at the center of the top riser of the unenclosed stairways; this is consistent with the exit access travel distance measurement in Section 1017.3. When enclosure is provided, distances are measured to the door of the enclosure.. Typically, travel distance is measured to the center of the door, ramp or stairway; however, there is an allowance for that point to be at any point along the door, stairway or ramp. The intent is to reduce subjectivity in the determination of exit/exit access configuration. The result is that a designer could literally measure to the far extreme of the two doorways leading out of a room to meet the separation requirements.
1007.1.3 Remoteness of exit access stairways or ramps. Where two exit access stairways or ramps provide the required means of egress to exits at another story, the required separation distance shall be maintained for all portions of such exit access stairways or ramps.
1017.3 Measurement. Exit access travel distance shall be measured from the most remote point within a story along the natural and unobstructed path of horizontal and vertical egress travel to the entrance to an exit.
** The length of travel, as measured from the most remote point within a structure to an exit, is limited to restrict the amount of time that the occupant is exposed to a potential fire condition [see Commentary Figure 1017.3(1)]. The route must be assumed to be the natural path of travel without obstruction. This commonly results in a rectilinear path similar to what can be experienced in most occupancies, such as a schoolroom or an office with rows of desks [see Commentary Figure 1017.3(2)]. The “arc” method, using as “as the crow flies” linear measurement, must be used with caution, as it seldom represents typical floor design and room layout and, in most cases, would not be the natural, unobstructed path.
The travel distance is measured from every occupiable point on a floor to the closest exit. While each occupant may be required to have access to a second or third exit, the travel distance limitation is only applicable to the distance to the nearest exit. In effect, this means that the distance an occupant must travel to the second or third exit is not regulated.
For exit access travel distances that include vertical elements, such as stairways or ramps, see Section 1017.3.1. For outdoor seating, see Section 1029.7.
1017.3.1 Exit access stairways and ramps. Travel distance on exit access stairways or ramps shall be included in the exit access travel distance measurement. The measurement along stairways shall be made on a plane parallel and tangent to the stair tread nosings in the center of the stair and landings. The measurement along ramps shall be made on the walking surface in the center of the ramp and landings.
1019.1 General. Exit access stairways and ramps serving as an exit access component in a means of egress system shall comply with the requirements of this section. The number of stories connected by exit access stairways and ramps shall include basements, but not mezzanines.
1019.2 All occupancies. Exit access stairways and ramps that serve floor levels within a single story are not required to be enclosed.
1019.3 Occupancies other than Groups I-2 and I-3. In other than Group I-2 and I-3 occupancies, floor openings containing exit access stairways or ramps that do not comply with one of the conditions listed in this section shall be enclosed with a shaft enclosure constructed in accordance with Section 713.
1. In buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1 with other than Group H or I occupancies, an exit access stairway serving an occupant load of less than 10 not more than one story above the level of exit discharge.
2. In Group R-1, R-2 or R-3 occupancies, exit access stairways and ramps connecting four stories or less serving and contained within a single residential dwelling unit or sleeping unit or live/work unit.
3. Exit access stairways serving and contained within a Group R-3 congregate residence or a Group R-4 facility are not required to be enclosed.
4. Exit access stairways connecting the first and second floors of Group R-1 bed-and-breakfast establishments. Stairways connecting the second and third floors in such occupancies shall be enclosed with fire separation assemblies having a fire-resistance rating of not less than 1 hour. Stairways connecting the basement and the first floor occupancies shall be enclosed with fire partitions having a fire-resistance rating of not less than 1/2 hour with 20-minute fire-resistance-rated door assemblies. Fire-resistance assemblies at stairways in Group R-1 bed-and-breakfast establishments shall not be required to be supported by fire-resistance-rated construction.
5. Exit access stairways and ramps within an atrium complying with the provisions of Section 404.
6. Exit access stairways and ramps in open parking garages that serve only the parking garage.
7. Exit access stairways and ramps serving open-air seating complying with the exit access travel distance requirements of Section 1029.7.
8. Exit access stairways and ramps serving the balcony, gallery or press box and the main assembly floor in occupancies such as theaters, places of religious worship, auditoriums and sport facilities.
9. Stairways serving outdoor facilities where all portions of the means of egress are essentially open to the outside.
10. Exit access stairways serving mezzanines complying with the provisions of Section 505.
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For what it’s worth, The NFPA 101 Life Safety Code Handbook also discusses using stairways as exit access rather than as exits.
CONCLUSIONS
There is arguably nothing in the building codes more important than Chapter 10: Means of Egress. If the purpose of the building code system is protection of public safety, health and welfare, it’s difficult to think of anything more critical than ensuring that occupants can escape from a building in the event of a fire or other catastrophe. Central to this is ensuring that each building, and each space within a building, has access to sufficient numbers of exits, with adequate exit capacity, and within the prescribed exit access travel limits.The notion that a required egress stair on an upper story of a building does not have to be enclosed and protected as an exit initially seems to be almost a contradiction in terms. It is important to differentiate between a stair that serves as a required exit access path and as such is subject to several specific requirements, and a non-required communicating or “convenience” stair, which may certainly be used for exit access by occupants who are near it, but which is in addition to the minimum number and distribution of required means of egress in the building and is, therefore not subject to all the requirements that apply to exit access stairways. The major difference with an exit access stairway is that, unlike an enclosed exit stair where the exit access travel distance ends at the door leading into the stair, with an exit access stair the exit access travel distance measurement continues down along the stair and across the lower floor until it reaches either an enclosed exit, or an exit door that discharges directly to the exterior.
