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All Calculators Chapter 10 - Means Of Egress Chapter 11 - Accessibility Chapter 14 - Exterior Walls Chapter 1 - Scope And Administration Chapter 24 - Glass And Glazing Chapter 2 - Definitions Chapter 33 - Safeguards During Construction Chapter 4 - Special Detailed Requirements Chapter 5 - General Building Heights And Areas Chapter 6 - Types Of Construction Chapter 7 - Fire And Smoke Protection Features Chapter 9 - Fire Protection Systems Cheat Sheets

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Decoded: Egress Terminology

This post was published in Doors & Hardware

In a previous column I explained how to calculate the required egress width based on the occupant load, and how to determine the number of occupants that a door opening will accommodate. The formulas used to calculate these values are consistent between the International Building Code (IBC) and NFPA 101 – The Life Safety Code, although the egress capacity factors vary slightly. So if you know the occupant load and the number of occupants accommodated by each door, it’s simple math to decide whether you have enough egress doors, right? Well…no.

As I mentioned in my previous column, there are other factors that affect the quantity and location of egress doors, beyond the general requirements for 2, 3, or 4 exits depending on the occupant load. For example, doors used for egress need to be located remotely from each other, and there are limitations on the distance a building occupant must travel to reach an exit. In order to understand these requirements, there is terminology that you should be familiar with.

• Exit Access – This segment of the means of egress is between the occupied portion of the building and the exit. If you imagine a typical school, the corridor that leads from the classrooms to a stair enclosure would be an exit access corridor. The path that you would travel through the classroom to reach the corridor would also be part of the exit access. Exit passageways are sometimes confused with exit access corridors, but an exit passageway is separated from the rest of the building by fire-resistance-rated construction and is part of the exit, not part of the exit access. Exit passageways often extend from the end of the exit stair to the exterior when the stair doesn’t discharge directly to the exterior.
• Exit – We often use the word “exit” as it is defined by the general definition – “a way out.” But in code terminology, an exit is the portion of the means of egress between the exit access and the exit discharge or public way. Some components that may be an exit are stairways and ramps, horizontal exits (often a double-egress pair of fire doors), exit passageways, and exterior exit doors at the level of exit discharge. In the school example, the enclosed stairway would be an exit.
• Exit Discharge – The portion of a means of egress between the end of the exit and the public way is the exit discharge, which typically begins when building occupants reach the exterior of the building, at or near grade level. If you reached the exterior door at grade level in the school example, the exit discharge might include a sidewalk leading from the exterior door to the street (the public way).

The exit access corridor is the portion of the means of egress that leads from the occupied portion of the building to the exit.

The exit provides a protected path of travel between the exit access and the exit discharge.

The exit discharge extends from the termination of the exit to the public way.

Other Terminology

When determining the quantity and location of egress doors, you will often find limitations that are imposed on the route.

• Travel Distance – The travel distance to an exit is measured on the floor along the natural path of travel, beginning at the most remote point, curving around corners or obstructions with a 12-inch clearance from the object, and ending at the beginning of the exit. The travel distance from a school classroom would be measured by starting in the most remote corner of the room, following the natural path to the door, traveling down the corridor, and ending at the stair door (the beginning of the exit). The IBC limits this distance in an educational occupancy to 200 feet for unsprinklered buildings, and 250 feet for sprinklered buildings. NFPA 101 allows a maximum of 150 feet for unsprinklered educational occupancies, and 200 feet for sprinklered educational occupancies.
• Common Path of Egress Travel – This is the distance that a building occupant must travel before two separate egress paths to two exits are available. In a classroom with one egress door, the common path of egress travel would be the path from the most remote location within the classroom out into the corridor where two paths become available – down the corridor to the left, or to the right. The common path of egress travel ends where that choice becomes available. In an educational occupancy, the IBC limits the length of the common path of egress travel to 75 feet. The maximum allowed by NFPA 101 for educational occupancies is 75 feet for unsprinklered buildings, and 100 feet for sprinklered buildings.
• Dead End Corridors – Where more than one exit or exit access doorway is required, the length of dead-end corridors (corridors with no outlet) are limited by the IBC and NFPA 101. In educational occupancies, the limit on the length of dead end corridors is 20 feet for unsprinklered buildings and 50 feet for sprinklered. In the IBC, the length of dead end corridors is not limited when the length of the dead end corridor is less than 2.5 times the width.

Another issue to consider when evaluating egress is the remoteness of exits. When two exits are required, they must be remote from each other, since two exits located in the same vicinity could become blocked during an emergency. To determine the minimum distance between exits, take the longest diagonal measurement of the area served by the exits. The distance between the exits must be at least one-half of the diagonal measurement for unsprinklered buildings, and at least one-third of the diagonal measurement for sprinklered buildings.

This article is not intended to be an in-depth study of each of these concepts, rather, an introduction to some of the egress-related terms that may affect the door openings serving an egress route. For additional information, refer to the code or standard that has been adopted in your jurisdiction. The allowable lengths shown in this article for travel distance, common path of egress travel, and dead end corridors are based on the 2021 editions of the IBC and NFPA 101. Values required by other editions may vary.

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Lori, Well-written article. I have just one suggestion: In figuring Exit Access Travel Distance, we use the length and width of the room (less the 12 inch clearance at the walls) rather than the diagonal distance. It might seem that the natural path to the egress door would be the diagonal, being the most direct, but often there is furniture in the way. In your example of the school, the student at the desk in the corner of the classroom may have rows of desks in his way. Whether he goes up to the front of the room, and then across to the door, or up one desk and over one, then up one more and over one more, etc., it adds up the same: length plus width. I believe this is explained in the IBC Code Commentary.

There is a fantastic resource that I think is under-advertized to help designers tackle these kind of confusing issues. It’s called the Interactive Guide to the 2012 IBC, which sells for about $50.

No I don’t work for the ICC, but I am lucky enough to have a copy and the infographics are amazingly helpful for just this sort of thing. Check it out:

http://shop.iccsafe.org/interactive-guide-to-the-2012-ibcr-pdf-download.html

Lori Article is well written and informative.

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ARCH 2614/5614 Building Technology I: Materials and Methods

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Refer to Chapter 10, IBC 2012 and "Egress" chapter of The Architect's Studio Companion, by Allen and Iano (course reserve).

Means of egress is continuous and unobstructed path of travel from any point in a building to a public way. It consists of 3 basic parts:

exit access (including corridors)

exit (basically the enclosed stair)

exit discharge (which leads to the public way)

Table 1017.2 Exit access travel distance

Table 1006.2.1 Common path of egress travel (Scroll down to Table 1006.2.1, 2020 NYS Building Code, based on 2018 IBC)

Section 1020.4 Dead-end corridors (Scroll down to Sec. 1020.4, 2020 NYS Building Code, based on the 2018 IBC)

Notes on egress:

generally no elevators * or escalators allowed (except as "accessible means of egress" in some circumstances): if unsprinklered, such elevator access must be from "area of refuge" or "horizontal exit."

"The Fire, Buildings and City Planning Departments [in NYC] are writing rules to govern what are called occupant-evacuation elevators — cars that can, in special circumstances, be used to move people down in an emergency."

"That would upend decades of codes and practices based on the notion that elevators are perilous and undependable in fires or other emergencies. Experts who have spent years studying building evacuations believe that approach has become outmoded and is in itself potentially dangerous as extremely tall skyscrapers increasingly pierce the New York skyline."

"Some requirements that the city is expected to impose for evacuation elevators have been anticipated in elevators at 3 and 4 World Trade Center. The floors in front of the elevator doors are raised slightly, to protect the hoist ways from water from sprinklers or firefighters' hoses. The capacity of the emergency generators was increased to provide uninterrupted service to those cars. The cars stop at every floor. Hoist ways are within cores protected by reinforced concrete walls at least 18 inches thick." [ NY Times, March 18, 2015 ]

provide guards where a floor surface is more than 30" above floor below; such guard rails are 42" high (except 36" in R-3 occupancies), and configured so that a 4"-diameter sphere cannot pass through.

need 2 means of egress for most buildings (1 for very low occupancies; 3 for 501-1000 occupants; 4 for more than 1000 occupants). Compute number of occupants by dividing floor area by "design occupant load" in code.

spaces with one means of egress permitted generally have a maximum occupancy of 49, except that number is only 3 for H-1, H-2, H-3; and 10 for H-4, H-5, I-1, I-3, I-4, R; and 29 for S occupancies)

buildings allowed one means of egress have similar occupant limits but also have maximum numbers of stories (generally 1 story maximum, except 2 for R-2 occupancies, 3 if sprinklered); plus maximum travel distances to exits.

typical minimum door size is 36" (which is also the most common door size for both egress and accessibility).

techniques to keep smoke out of egress stairs: smokeproof enclosures can be exterior "balconies" separating the entrance to the stair from the occupied space and providing a means for smoke to be exhausted to the exterior before entering an enclosed stair; or they can use ventilation ducts provided for that purpose; or, in certain cases; stairs can be mechanically pressurized so that smoke doesn't enter.

Disclaimer: Students are responsible for material presented in class, and required material described on course outline. These notes are provided as a tentative outline of material intended to be presented in lectures only; they may not cover all material, and they may contain information not actually presented. Notes may be updated each year, and may or may not apply to non-current versions of course.

Copyright 2007–2021 J. Ochshorn. All rights reserved. Republishing material on this web site, whether in print or on another web site, in whole or in part, is not permitted without advance permission of the author.

1006.2.1 Egress Based on Occupant Load and Common Path of Egress Travel Distance

• The number of exits from foyers, lobbies, vestibules or similar spaces need not be based on cumulative occupant loads for areas discharging through such spaces, but the capacity of the exits from such spaces shall be based on applicable cumulative occupant loads .
• Care suites in Group I-2 occupancies complying with Section 407.4 .
• Unoccupied mechanical rooms and penthouses are not required to comply with the common path of egress travel distance measurement.
• Buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 . See Section 903 for occupancies where automatic sprinkler systems are permitted in accordance with Section 903.3.1.2 .
• Group H occupancies equipped throughout with an automatic sprinkler system in accordance with Section 903.2.5 .
• For a room or space used for assembly purposes having fixed seating , see Section 1030.8 .
• For the travel distance limitations in Group I-2 , see Section 407.4 .
• The common path of egress travel distance shall only apply in a Group R-3 occupancy located in a mixed occupancy building.
• The length of common path of egress travel distance in a Group S-2 open parking garage shall be not more than 100 feet.
• For the travel distance limitations in Groups R-3 and R-4 equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.3 , see Section 1006.2.2.6 .

Related Code Sections

IBC: 10 Things to Know for the ARE

NOTE : The ARE 5.0 is now using the 2018 IBC. This post is still accurate, but originally referenced the 2015 IBC. I am in the process of updating it now.

ARE 5.0 code questions can cover a large portion of your exams. Up to 22% of the Programming and Analysis questions. Up to 22% of the Project Planning and Design questions. And up to 14% of the Project Development and Documentation question. Everyone will go into the ARE 5.0 exams with some weaknesses, but I highly recommend that the building code NOT be one of yours!

The tough part is that there are a lot of things to know about the building code! As a primarily residential architect my experience is mostly with the International Residential Code. So before all my ARE 5.0 exams I had to spend a lot of time studying the IBC, which you can find for free right here: 2018 International Building Code . Fortunately I also had a copy of Ching's Building Code Illustrated (BCI). I think it's important to read the actual code, but BCI really helps break things down with diagrams and bullet points. After studying for, and taking those three exams, here are my Top 10 Things to Know from the 2018 IBC:

1. What's in Table 508.4?

2015 IBC Table 508.4

Table 508.4 of the 2018 IBC shows the IBC Required Separation of Occupancies . This is a concept you'll see on multiple exams, both in the planning exams (PA and PPD) and in the construction/detailing exam (PDD). My recommendation for learning this is not to memorize the actual table, but memorize the number (508.4) so you can quickly find it in the provided resources on the exam. You can expect questions about determining the required separation between occupancies AND how to choose a wall system that meets those requirements. Check out this video on how to determine the required fire separation using the table.

2. Dead End Corridors

A dead-end corridor is a hallway the leads only to an exterior wall with no exit. A window does not count as an exit. The maximum distance of a dead end corridor is 20ft, though there are always exceptions, like certain occupancies and whether or not the building has sprinklers. The link takes you to Chapter 10 of the IBC, read Section 1020.4 for specifics of dead end corridors.

3. COMMON PATH OF TRAVEL

The IBC defines common path of travel as, “that portion of the exit access travel distance measured from the most remote point within a story to that point where occupants have separate and distinct access to two exits or exit access doorways.” In real words, you measure from the furthest corner in a room to the point where someone could egress two different ways. Marty Huie has a good video about Common Path of Travel . The maximum distance of the Common Path of Travel is set in the 2018 IBC Table 1006.2.1 which also has restrictions for spaces with only one exit.

4. Door Locations and Max Projection into Corridors

With a few exceptions, doors must swing in the direction of egress, meaning doors from rooms will swing out into corridors people are trying to use for egress. IBC limits the amount of this swing in Section 1005.7 Encroachment. (A lot of the things you need to know about the IBC are in Chapter 10 Means of Egress ). When fully open, a door can only project 7″ into a hallway. When the door is being opened it can't reduce the width of the corridor by half. You have to account for this when placing doors, often times you will see them recessed into alcoves so that they can be fully opening and not reduce the required width of the hallway. I recommend remembering 7″ and “reduced by half”.

5. RAMP SLOPE

There used to be a ramp slope vignette on the old Building Design and Construction systems exam. That exam is now part of Project Planning and Design and Project Development and Documentation. So you may see ramp slope questions on more than one exam. You can read all about ramps in the 2015 IBC Section 1012 First, you need to define a ramp by it's slope. If it's less than 1:20 it's just a sloped surface, and doesn't require a handrail or landing. If it's steeper than that it's a ramp, and it can have a maximum slope of 1:12 or 8″ or 1″ per 12″ or 1ft per 12ft. Those are all the same things, just written in four different forms. The maximum rise is 30″, so if you have to go up more than 2.5 feet you'll need a landing mid way. That landing (and others) have to be at least as wide as the ramp and at least 60″ long. Minimum width is 36″ though this is absolute minimum and the ramp may have to be wider due to requirements of Section 1020.2

6. USE AND OCCUPANCY CLASSIFICATION

Chapter 3 Use and Occupancy Classification is where the different Occupancy Groups are defined. These are the most general classification of the use of a building, like Assembly, Business, Educational and Factory, etc. You don't need to memorize these, but it's good to understand what the general definitions of these groups implies. You also may be asked to choose an Occupancy Group based on a description of what the space is used for. In that case it would be helpful to refer to Chapter 3 to make a determination of what the best Group is.

Can you answer these questions? Image from Building Code Illustrated.

Atriums are covered in 2015 IBC Section 404 and defined in Chapter 2: “An opening connecting two or more stories other than enclosed stairways, elevators, hoistways, escalators, plumbing, electrical, air-conditioning or other equipment, which is closed at the top and not defined as a mall. Stories, as used in this definition do not include balconies within assembly groups or mezzanines that comply with Section 505.”   They're basically saying an open space that's more than one story tall that's not obviously some kind of chase. An elevator shaft is clearly not an atrium. The biggest thing to know about atriums is the fire and smoke protection requirements. This is handled in Section 404.6 Enclosure of Atriums. With some exceptions, an atrium needs to be surrounded by a 1-hour fire barrier.

8. FIRE WALLS, BARRIERS, PARTITIONS

Speaking of Fire Barriers, it's important to understand the difference between the three primary fire resistant wall types you will encounter. The key difference is not the number of hours, but the construction of the walls with relation to the floor, roof and ceilings. Read the portions on horizontal and vertical continuity. These are all in Chapter 7 Fire and Smoke Protection Features . Fire Walls: Fire Walls are covered in Section 706. They are required to extend from the foundation to 30 inches above the roof. Yes, all the way from the foundation to above the roof. A fire wall can be used to separate one structure into two separate buildings, as far as the code is concerned. They will be rated between 2-4 hours, depending on the Occupancy Groups. See Table 706.4 Fire Barriers: Fire Barriers are covered in Section 707. They must be built from the floor to the underside of the deck above (vertical continuity) They are used for many of the key separations, like separating occupancies, protecting exits, protecting atriums (see above) and more. Fire Partitions:  Fire Partitions are covered in…Section 708. See the pattern? These offer the least amount of protection of the three. They are generally used to corridors or other interior spaces. They must go from the floor to the underside of the deck above -OR- from the floor to a rated ceiling.

9. Mezzanines

Mezzanines are basically free space. They don't count against the floor area or stories limit, but they come with some restrictive requirements. Of course, there are exceptions, per usual code is relaxed when you add sprinklers or more exits. Keep in mind the goal of the mezzanine (per code eyes) is to allow a smaller space above, and open to, the space below. Like a reading room above a library stack and etc. Not considering exceptions, a mezzanine can be a maximum of 1/3 the area of the room it's in, and has to be open and accessible from that room (mezzanine walls are max 42″ high). These requirements are relaxed if the occupant load of the mezzanine is fewer than 10 people or there are two or more exits from the mezzanine. There are others, but these are the big two. Read more about mezzanines in the 2015 IBC Section 505.

10. Maximum building height and area

I personally feel this topic gets more than it's fair share of press. The amount of time people spend studying for, and stressing about building height and area doesn't seem to match up with how much this stuff is actually on the exams. BUT, it's good to know and even better, it got EASIER in the 2015 IBC. Allowable Building Height: There are two height limitations, actual height in feet, and number of stories. You can now read these entirely from tables, with no calculations or formulas or adding 20 feet etc. Maximum height is in Table 504.3. Find your occupancy on the left, then choose sprinklers or no sprinklers, and read your max height directly from the table in the column that matches your construction type. Allowable Number of Stories: This works the same as Building Height. See Table 504.4 Allowable Building Area:  This is the big one. It still requires a formula, but it's less involved than it was before. See Section 506 for Allowable Building Area. To start, find your Allowable Area Factor in Table 506.2. This works the same as above, find your Occupancy on the left, then read across to find your Allowable Area Factor in the column that matches your construction type. On the ARE all this stuff should be given to you. Then you need to go to Section 506.2.1 through 506.2.4 to find your specific area increase formula. There is a slightly different formula depending on whether you are mixed-use single story, single occupancy multi-story, etc. If you have a single-occupancy multi-story building your formula will be Allowable Area = [Table Value from 506.2 * (Frontage Increase)] * Number of Stories. Frontage Increase is a whole different situation, so let's say it doesn't apply here. Your formula for total area becomes your table value multiplied by the number of stories. Easy! I have a more in-depth example in the PPD/PDD Study Questions Course . See Week 5 Question 34.

11. EXCEPTIONS

OK, bonus tip here. There are exceptions to pretty much everything I've covered above. It's good to know they're there and what their purpose is. In your studies focus on the exceptions that relate to sprinklers, exits, and number of people.  Pay less attention to things like 505.2.3 Exception 4 which allows equipment platforms in Industrial facilities to be glazed on all sides. If you actually get that question on the exam and miss it because I told you don't worry about it…sorry?

12. Maximum FLoor Area per occupant load

Speaking of people, that reminds me. It's good to know how many people are allowed in different spaces. This is found in Table 1004.1.2. Find the function of your space in the left column, then find the occupant load factor in the column on the right. To find how many people can be in your space you divide the area of the space in question by the occupant load factor. Make sure you are aware of Net (actual floor area) vs Gross (total floor area including things like corridors and stairs). The space function is more specific than your Occupancy Group, so make sure to read through the list to find the one that is most accurate.

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Mezzanine with Single Means of Egress

• Thread starter MAGB
• Start date May 17, 2021

Registered User

• May 17, 2021

I am wondering which table I use to determine the common path of egress travel for a mezzanine per the 2018 IBC. Per 505.2 A mezzanine "shall be considered a portion of the story below." Given that would I then use table 1006.2.1 Spaces with One Exit or Exit Access Doorway to determine maximum common path of egress travel that would allow for a single exit? The building is otherwise a single story building. Otherwise would I need to look to 1006.3.3 Stories with One Exit or Access to One Exit ? For a storage occupancy this would be the difference of 100' vs 75'. Thank You!  

You would comply with the CPET requirements of Table 1006.2.1.  

If the entire first story only has one exit, then you are limited to Table 1006.3.3(2).  

Thank You! The first story has many exits.