ARE Live: Understanding Egress Systems
Learn about the who, what, where, when, and how of designing egress systems.
In this episode, Chris and Garric walk through a scenario of a hypothetical project, the Black Spectacles Brewery. Here’s the scenario we worked through in this episode:
Black Spectacles is opening its own brewery with an existing building. The team will renovate the space. The building is constructed of wood studs, gypsum board sheathing at the interior, and siding at the exterior. The roof structure is a trust system with plywood sheathing and architectural shingles. The flooring is sealed, concrete floor. The building does not currently have a sprinkler system. The building will be equipped with a brewing area, tank storage, and full commercial kitchen. Restroom and plumbing calculations have already been performed at this time.
The second floor attic space is not being considered during the renovation and will not be evaluated for egress compliance. Determine if the building provides adequate egress design to be functional following the renovation of the proposed layout.
Define the Who, What, Where, When and How
When first learning to design egress systems, it can get confusing with a lot of different avenues. The who, what, where, when, and how method can create a quick, easy way to double check yourself when going through your design.
Here’s how this framework can play out:
First, who: Who needs to exit the building? This is where occupant load comes in handy.
Second, what: What do we need to do to get these occupants to safety? This will be our number of exits.
Third would be where, so where are we having people exit the building?
Fourth is when: When do we need to have these people out of the building? This sets up our question of determining travel distance and our overall fire rating. The fire rating of components allows individuals enough time to exit the space.
And finally, how: How have you accomplished your egress plan for the project? This provides a way to make sure you can double check your work at the end.
This method helps you get down to the very basics of things. A lot of times, especially for young professionals or newly licensed architects, that can become a little overwhelming. So having this moniker gives you a framework that you can structure around.
Where is Egress on the ARE?
Even though the who, what, where, when, and how framework is really helpful for designing a real egress system from beginning to end like you would if you were working on a project for real, the ARE isn’t structured that way. There’s not a specific exam division on egress. Instead, egress is covered across a few different divisions: PA through PDD. Here’s how egress mights how up on those exams:
Egress on PA
If you look at objective 2.1 for PA, it’s about identifying relevant code requirements for buildings and site types. When a lot of people think about that for PA, they’re thinking about maximum building area, height, construction types, and things like that. But it also applies to egress as well, if you look at the last sentence for that objective.
It talks about conducting an initial code analysis, which should consider the who and what question this episode discusses. What types of occupants are you going to have, and how many exits will you need?
Egress on PDD
On the PDD division, we have objective 2.2, which talks about applying building code to the building design. That pretty clearly covers a lot of egress components, and NCARB’s information about objective 2.2 even talks about fire separation required, egress, and maximum occupant loads.
On PDD, you’ll be thinking about the where and when in our framework: the egress paths and fire ratings and things like that.
Also on PDD, if you look at objective 4.1 and 4.2 where it’s talking about adherence to requirements at a detailed level, which aligns with the how that we’ve outlined here. When it comes to the derailed level for egress, you’re probably talking about specific door widths, corridor widths, door hardware, and things like that.
Who: Defining the Number of People Needing to Exit a Space
On the exam, you’ll be given relevant code sections, floor areas, and relevant distances will be provided for you, so you’ll have to appropriately apply what’s given to you in order to find your answer.
To calculate your occupant load, you’ll take the square footage of the room and divide it by the figure provided to you in your code section; in this episode, we reference table 1004.5 in the International Building Code or IBC. This calculation gives you the number of occupants you can have in each room based on the square footage. If you get a partial number, always round up to the nearest whole occupant.
Another area where people can get tripped up is the difference between net and gross square footage. Net square footage refers to the area that’s available for use. In the tank room, for example, you wouldn’t count all the space where the tanks are located and your square footage would end up being a different number.
But for the purposes of the ARE, you’re going to be provided with the square footage numbers, so you don’t have to think too much about the net vs. gross difference, since they’re providing that number for you.
If you saw this on the ARE and started to think about deducting the tanks or anything like that—don’t go down that path. If there’s nothing on the plan to tell you how big the tanks are, it would be totally unfair for you to have to estimate. So don’t go down that path. Just use the information that’s provided to you on the documents you’re given.
What: Determining the Number of Exits
Once you have your number of occupants, your next step is determining what you need to do to get them safely out of the building, or how many exits you need to have. As a starting point, you’ll consider the requirement of needing at least one.
The question then becomes can you maintain the building with one exit, or will you be required to add a second one? When determining your number of exits, refer to the code provided to you, but also remember your scenario as well. If, as is the case in this episode, the building has no sprinklers, that will change the number of exits you need, and where they’ll be placed.
Where: Designing Paths of Egress
By the time you get to the where part of an egress system, after you’ve determined how many people and how many exits you’re dealing with, you’re probably moving into the PPD portion of the exam.
That’s probably where you stop at preliminary design or the early parts of the schematic design like the PA exam covers. That said, it is possible that you would see a similar question on the PPD exam too. That’s why we suggest studying for the PA exam first, and then moving on to PPD and then PDD, moving through those three divisions in order like you would on a project.
You might study these occupant loads and number of exit calculations and then only see one question, or none at all, on the PA exam—but then you’ve already covered these basics by the time you get to PPD. So there’s no harm in learning these topics a little early in your ARE journey, because they may apply earlier than you think.
To design your egress paths, remember the scenario from the beginning. In this episode, the scenario is for an existing building that’s being renovated, so you’re not having to create any new exits.
Refer back to the code to find out how many exits are required per occupant load, which will help you determine if you’re meeting that requirement. In this episode’s example, the occupant load is 127 occupants, which has three required exits, but this building has five—so we meet the code requirement there.
When: How Fast Occupants Can Leave a Building
The question being answered in this section is when do we need to get our occupants to safety, or how quickly do they need to exit the building?
Since you’re working with an existing building in this scenario, you need to determine if the building is required to have any type of rating or timeframe during which the occupants can occupy the building during an evacuation. To find out, refer to Section 602, as well as table 601, which lays out the fire resistance rating requirements for building elements and breaks down different categories of construction for resistance.
To see how the rest of the who, what, where, when, and how narrative plays out in egress systems, and to see how Garric and Chris work through the answers in more detail, check out the recordings below