Occupant Load: How Many Is Too Many?
Every office project begins with the same essential question: How many people can this space safely hold? It’s not just a guideline—it’s a foundational decision that influences safety, design, permit approvals, and even project budgets.
In Ontario, the answer is regulated by the Ontario Building Code (OBC), which sets out clear methods for calculating occupant load and ensuring safety. With changes to the OBC coming into effect as of 2025, it’s more important than ever to understand how occupant load impacts retrofit projects.
What Is Occupant Load?
Occupant load refers to the maximum number of people that can safely occupy a space at a given time. This number is calculated using factors such as size, layout, and use, and helps determine the number of exits, corridor widths, fire alarm systems, and washroom counts that must be built.
Because of its significance, only qualified professionals—architects, engineers, and building officials—can make official occupant load calculations. And while the math might seem simple, its implications for design and construction are anything but.
Methods for Calculating Occupant Load
When calculating occupant load, there are two common methods:
The Occupant Load Factor Method
The “Designed For” Method
1. The Occupant Load Factor Method
This method is the go-to approach early in the design process, before a finalized layout. It uses a standard value set by the OBC—9.3 m² (or 100 ft²) per person for offices.
Formula:Floor or Space Area ÷ Occupant Load Factor
Example: Let’s say you have a 605 m² office suite.
605 ÷ 9.3 = ~65 people
This assumes a typical mix of workstations, offices, and meeting rooms, and provides a clear, common starting point for landlords, tenants, and designers.
2. The “Designed For” Method
Once you know how the space will actually be used—how many desks, offices, and seats are going in—you can propose a lower or higher occupant load based on that specific layout.
Example: If the same 605 m² suite includes:
1 reception desk
9 private offices
40 open-area workstations
Then the occupant load is:
1 + 9 + 40 = 50 people
⚠️ This method is only valid if the occupant load is justified based on the actual design and use of the space.
Key Change in the 2024 Ontario Building Code
As of January 1, 2025, the OBC introduces a key shift: the Occupant Load Factor Method becomes the default.
This means:
Designs based on headcount (the “designed for” method) are discouraged.
Using the “designed for” method will require extra documentation and may face approval delays.
Building officials may not accept a lower occupant load without thorough justification.
It will no longer be easier to design for fewer occupants.
Impact Example: the previous suite (50 people using the “designed for” method) must now be designed for 65 people by default. That means:
At least two suite doors must swing outward,
Instead of one door swinging inward, which was acceptable before.
Increasing Occupant Load in Existing Spaces
If a tenant or landlord wants to add more people to a space, two scenarios may occur:
Scenario 1:
Proposed load ≤ Occupant Load Factor
If the suite was designed for 50 but 65 is allowed, then 15 more workstations can be added without additional justification.
Scenario 2:
Proposed load > Occupant Load Factor
Common in high-density areas like training rooms or conference spaces. In this case:
A qualified professional must analyze whether exits, corridors, and washrooms support the increase.
Why Does This Matter?
Modern offices now include communal spaces like:
Conference suites
Training rooms
Lounges
Flexible collaboration areas
Each change impacts occupant load and must comply with safety codes.
Especially in older buildings, previously acceptable loads may no longer meet current OBC standards.
The Help of Clearspace
Occupant load is a critical safety and design consideration in any office project. With the updated 2025 OBC regulations, early planning and professional guidance are more important than ever.
At Clearspace, we help you navigate these changes with confidence. When updating a suite, we ensure your space meets the latest standards—without compromising design intent or functionality. We factor occupant load into every step, so you can move forward with clarity, avoid expensive surprises, and deliver a space that works for everyone.
