• Mark

What Occupancy is this???


How come no one has ever opened a laundromat, bowling alley, bar?


One of the major subjects occurring through all three of the planning exams (PA, PPD, PDD) involves the occupancy classification of the building in question.


How does one figure out the occupancy classification of their building? How many occupancies can there be in one building? What does occupancy mean in terms of building codes? And how many damn parking spaces will the building require?


DISCLAIMER: There is a lot more to this topic than I will cover in this brief article.

Occupancy classification will ABSOLUTELY be on your ARE.

I recommend you read Chapter 3 (and 4) of the IBC, and if you have the version with commentary for further clarification, even better.


The occupancy classification of a building is based on how the building will be used.

Put another way - what activities will occur in the enclosed space.

The answer to the first question comes directly from the International Building Code - Chapter 3 (Section 302) - Classification. This is only a broad overview, please actually read the code for this.


There are 10 Occupancy Classifications:

You do not have to memorize these - but it's not that hard to do it. (For the ARE it is likely that your case study references will have a snippet of the IBC applicable to your situation)


A - Assembly - Basically any kind of place where people ASSEMBLE (who uses the term in the definition?) for entertainment, dining, or group activities (Restaurants, Theaters, Gyms, Casinos, etc. (Including sporting events))

B - Business - Professional Service Facilities (Offices - architects, accountants, doctors) Call centers, Motor vehicle showrooms, Education above 12th grade

E-Education K-12, Daycare - Assuming that there are people in charge of the students that will direct them in case of emergency

F - Factory - Basically Industrial manufacturing, fabricating, and assembling. (A B-business can contain some accessory manufacturing, but if the primary use of the facility is MANUFACTURING then it is likely a F use) A Factory will have offices and storage as accessory parts of the building, but will still be a factory.

H - High Hazard - explosive, combustible, corrosive, toxic materials, stored in a facility

I - Institutional - group housing falilities, jails, hospitals, rehab - places people sleep under the supervision of other people

M - Mercantile - (Stores) - any building used for the display and sales of merchandise (Target, grocery stores, boutiques)

R - Residential - (Places people live) - There are multiple types of R classification divided basically by the length of time they are staying and who owns the property) R1 - Hotels, R-2 - apartments and dorms, R-3 - Houses

S - Storage - pretty self-explanatory (often in small doses as an accessory use to the Primary Occupancy)

U - Utility - Not for Human Occupancy - Buildings that house utilities like power, telephone, sewer equipment.


Most frequent encountered uses (This means ARE) are A, B, E, M, and R. (In practice, I have not yet worked on a Factory, High Hazard, Institutional, or Utility project)


Buildings may contain more than one occupancy classification.

[This gets a bit technical] In fact, there is NO LIMIT to the number of uses a building may have. If one space has multiple uses - "A room or space that is intended to be occupied at different times for different purposes shall comply with all of the requirements that are applicable to each of the purposes for which the room or space will be occupied." And there are ACCESSORY USES (IBC 508.2) which do not factor into the overall use of the building if they meet certain restrictions.]


I can recall one project that contains all of the following uses: inn, restaurant, commercial kitchen, banquet hall, theatre slash meeting rooms, general lobby, community gathering space, and several different storage areas with different purposes. (Points to anyone who comments with the correct occupancies in this example)


Occupancy Classification determines Allowable Building Height

For the third question, you need to do some work. Once you know the Occupancy Classification of your building - there are 2 charts that tell you how tall in height, and how tall in Number of Stories your building is allowed to be. This is Section 504 of the IBC.

NOTE: You will also need to know your building CONSTRUCTION TYPE (IBC Chapter 6) to find this answer.


Occupancy Classification determines Allowable Occupancy

(aka People in a space)

There is a limit to the number of people allowed to occupy a space, based on the size and how that space is going to be used. This is primarily for public safety. As such you can fit more people in a lecture hall than you can in a dining hall. Hotel rooms are not meant to be occupied by 40 people. People and equipment in an office building take up less space than people and equipment in a commercial kitchen. Etc etc.

The number of people in a given space determines the size and number of exits and stairs the building requires.


Occupancy Classification determines required fire ratings

Every part of a building that is of a different use has to be kept separate from the other uses for purposes of fire safety. Let's say there is a strip mall that has a battery store next to a daycare next to a nail salon. Each of these poses a different risk in terms of flammability, and in terms of occupants. It is only right that the walls that separate these different uses be protective enough to allow for the people next door to get out of the building before the fire would overtake their space.


What is the deal with Parking Requirements?

Parking requirements are a municipal zoning code ordinance. They vary from town to town (and case study to case study.)

The goal is to calculate the maximum number of occupants that will use your building (or building campus), and divide that by the applicable requirement by use (ZONING REQUIREMENT), and this will give you the number of required spaces. Parking requirements VARY BY USE. ALWAYS ROUND UP!

And look. THIS IS NOT STRAIGHTFORWARD. Every ARE question I ever got about parking was confusing and poorly written. An art gallery will a different number of parking spaces than an apartment building than a theatre than a grocery store, et al.

I suggest you solve the parking requirement question as best you can, check your work quickly (maybe review later), and move on. It is only worth one point, DO NOT let it keep you from answering other problems.





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