Ensuring Safe Building Evacuation with Egress Plans and Occupancy Load

I would like to introduce you to a totally new kind of drawing, which is normally submitted on commercial projects. This is a drawing which we call the egress plans and occupancy load. One of the most important things when we're working on buildings is the consideration of saving lives, and so that if something bad were to happen in a building, that people could effectively depart the building safely.

This is a project we worked on in San Diego. It is a five-story historical renovation where we have two layers of underground parking, and we also have three floors above. So I'm going to zoom into this area in the top right so we can discuss some of the specifics that are going on.

This is a building that is in the central business district core of San Diego. It's a type three construction. What this means is that we're including metal, concrete, and wood.

The building is fully sprinklered. It's showing that it's technically four stories tall. We have calculations right here that show the square footage of the building, and then we have something down here called occupancy classifications.

What's happening is that in this building, we have on the first floor, including the mezzanine, a restaurant and a commercial kitchen. And if you zoom into this area, you can see that we have occupancy load factors, and what this means is that when the building is being designed based upon the type of construction and the type of occupancy load factors, we're expecting so many people to fit in a certain level of density. So you can see in restaurants, we're showing one person per every 15 square feet.

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In the kitchen, where we have a lot of big equipment, we're expecting one person per 200 square feet, and on the upper floors, which we're labeling floors three through five, we're showing one person per 100 square feet. Now, we also have something called occupancy separations, and what this means is that when we have certain sizes of buildings that we need to separate the areas into manageable fire zones so that the fire will not spread over a larger area. We have square footages, and then I'm going to slide down and look at the occupancy area analysis.

So you can see that we have, for the entire building, we have different occupancy classifications. If you look back up here, you can see that on the first floor for the restaurant and kitchen, the code is assigning those kinds of occupancy load factors to an assignment of an S3 analysis. We have an S3 down here, and you can see that we have so many square feet that are assigned to that particular use.

We have our occupancy load factors, and so you can see that we're saying, when you do all of this math, that the occupancy load that we're assigning is below a factor of one. So that means that we have more than enough square footage assigned to safely keep people within that area of the building. When I go up the floor, you can see that again, for example, on the third story, the third floor, which is technically the second story, our factors are also low.

So the purpose of this chart, and it gets to be pretty convoluted doing all the math, is that we're saying that we're safely assigning numbers of people to the density provided in the building. We also have MOE, which means means of egress. And what happens with this is that when you think about it, if you are in a school, you notice that the hallways are typically wider than if you are in an office building.

That's because the school has more people who need to evacuate out of the building in an emergency. And so based upon occupant density, there are building code requirements that say that the hallways need to be particular widths. So I'm just going to zoom back and just pan over to this basement area in through here.

When you look at this, you can see that I have my floor plan. So what's going on is you have my floor plan. We're on the first floor, and you can see that we have a diagonal line that's going this way.

The line going to the right and a diagonal line going this way. There are building code requirements that say when you were calculating the number of exits required to safely evacuate people out of the building, that the exit doors are no greater than 50% of the diagonal length of the space. So you can see that right here in the kitchen, we're showing that we have 2,600 square feet.

We have our occupancy classification. We look at the square footage, 2,592, divided by the 200, which is the occupant's load for that building. And we're expecting a total of 13 people to be able to safely work within the commercial kitchen.

In the restaurant area, I have 4,105 square feet. Here's my occupancy classification. But because it's the dining area, I have 15 square feet allocated per person.

So the maximum occupancy load in the restaurant is 274 people. So this space down here can safely handle 274 people in the restaurant and 13 people working in the kitchen. You can see the arrows, and these arrows are indicating the direction of travel.

And so we have a door up here. We have 1, 2, 3, 4 doors that are happening for this area. And if you add up the number of 5, they're expecting that 5 people would evacuate the kitchen out of this door.

Again, this line right through here represents the separation between the kitchen on the right and the restaurant on the left. So 5 people from the kitchen staff could evacuate through the building this way. 40 people from the restaurant can evacuate through this door.

138 people through this door down here. And another 138 people through this door here. So what we're doing is we're saying, okay, we have this much square footage.

We have these many people who can safely occupy that space. And we are showing the regulatory agency the number of people who could evacuate the building through different means of egress. I'm going to slide down here and work on showing you this floor, which is the fourth floor.

Now, what's happening here is that we worked on this building in phases. Initially, we were working on the renovation of the building, and we came later on and did the tenant improvements. And tenant improvements are where we break the spaces into different offices.

So this is the fourth floor of the building. You can see I have a stairway down here. I have a stairway up here.

I have a hallway that's separating offices on this side from offices on this side. So what's happening is in this area over here on the right, I have a diagonal length of 135 feet this way and a diagonal distance of right around 95 feet this way. I have 1,974 square feet.

I have my business classification. I have my occupancy load of 100 square feet per person. So this space, which is 1,974 square feet, is rounded up to 2,000 square feet, so I can have a maximum occupancy of 20 people within this area.

And so what we're saying is we have the diagonal distances. The distances between the doors can be no greater than 50% of this longer line. And I'm showing that 10 people would exit through this door right here.

And 10 people would exit through this door down here. Over on the left-hand side, you see I have my diagonal distances. You're seeing that I have 5,500 square feet, my occupancy load, of total 56 people.

And so I'm saying that 26 people could exit out this door and 27 people would exit out this door. So, again, I have 10 people exiting out this door, 26 maximum out this door. If I go through the hallway and I get down to my protected stair enclosure, which is up here, a total of 36 people would be anticipated to depart from this floor exiting through this stairwell.

If I go down here, you can see that I have 10 people coming out of this door, 27 out of this door, and 37 people totally coming out into the stairway this well. Now, what I'd like to bring to your attention, too, is it's saying here required means of access width of 44 inches. So per the building code, based upon the number of people who would be evacuating from this floor, the building code requires a minimum width of 44 inches.

But we're providing a width of 6 feet. So the hallway that we're providing for egress is greater than the code requirements for departure from the building. If you would, look at some of the other drawings that are in here and just see how you can understand.

So I'm just going to zoom into this area down here. I'll do my panning. Similar kind of situation.

This is the fifth floor. I have a square footage of approximately 2,600 square feet. I have my business classification of 100 square foot per person, so I can have a maximum occupancy load of 26 people.

And so, again, I have two doors. Thirteen people could leave out of this door. Thirteen people leaving out of this door.

This space over here has around 5,300 square feet, 100 square foot per person allocated for the business classification. Total occupancy load of 53 people where 26 would depart this door here and 27 would depart this door here. I take this 27 departing here, the 13 here, and I'm showing that a total of 40 people are anticipated to be able to depart into the fire corridor, the stairwell, through this door.

Again, I'm showing my required width of 44 inches. Again, we're providing 6 feet of width for evacuation. If you would, please, spend some time, look at this drawing, and I think you'll understand that the building department does its best to take care of making it so that people can safely and effectively depart buildings.

What we're going to do next is to look at our tenant improvement drawings for occupancy load and means of egress.