How Small is Too Small? Understanding Suite Sizes and Egress Rules
Introduction to Modifying Office Spaces
At first glance, merging or subdividing office suites might seem like a straightforward task. While merging usually goes off without a hitch, subdividing an existing space is typically met with a couple of challenges—especially when it comes to meeting the Ontario Building Code (OBC) standards. These rules become a lot stricter because safety and fire protection must come first.
Why Subdividing Matters
Any time you build new walls to divide up a suite, you’re not just changing the layout—you’re changing how people enter and exit the suite during emergencies, and how first responders must enter the space if needed. That’s why the OBC lays out some very specific requirements. It’s about making sure every suite—old or new—meets safety standards for everyone who walks through the door.
Suite Size Thresholds: Small vs. Large
The OBC establishes a key size threshold at 300 m² (about 3,230 ft²), distinguishing between small suites (under 300 m²) and large suites (over 300 m²). This distinction directly influences key design requirements, particularly regarding the number and placement of doors, as well as how those doors operate.
Number of Entry/Egress Doors
Egress doors serve as the primary doors used by occupants to exit a suite. For larger suites (over 300 m²), the rules are clear: two egress doors, minimum. That way, if one door becomes unusable during an emergency, people have another way out. Smaller suites (under 300 m²) can get away with a single door but must still comply with all other egress standards.
Location and Layout of Egress Doors
The placement of egress doors is just as important as how many are provided. The OBC closely regulates dead-end corridors—hallways that offer only one direction of travel toward an exit or a point where multiple exit routes become available—as they can pose serious risks during an emergency. Because of this, the OBC keeps a close eye on these layouts, limiting both their allowable length and the number of occupants they can safely serve.
Egress Doors in Suites
Larger suites with two egress doors help mitigate the risks associated with dead-end corridors by offering alternative exit paths within a space. This reduces dependence on any single route during an emergency. Oppositely, smaller suites with a single egress door that opens into a dead-end corridor are permitted under very few circumstances and are generally best avoided.
Door Swing Requirements
For suites exceeding 600 m² (6,430 ft²), the OBC requires egress doors to swing outward in the direction of travel toward the exit. This design facilitates faster and safer evacuation by preventing doors from obstructing the flow of movement during an emergency.
Summary Table
This table summarizes the key thresholds and related egress door requirements when subdividing office suites under the OBC:
| Suite Size | Number of Doors | Door Location and Dead-End Corridor Considerations | Door Swing |
|---|---|---|---|
| Less than 300 m² (< 3,230 ft²) |
1 door is allowed | Door opening into dead-end corridors only allowed under strict conditions | Inward or Outward |
| Greater than 300 m² (> 3,230 ft²) |
2 doors minimum | One door may open into a dead-end corridor only if the other does not | Inward or Outward |
| Greater than 600 m² (> 6,430 ft²) |
2 doors minimum | One door may open into a dead-end corridor only if the other does not | Outward only |
Conclusion
Subdividing an office suite isn’t just about putting up a wall—it’s about getting the details right. The OBC introduces strict, safety-driven requirements that can dramatically impact layout, timelines, and budget if not properly accounted for.
At Clearspace, we know how to turn technical requirements into smart, functional designs that work in the real world. We’ve done this before, and we’re ready to do it again. If you're planning to rework your office layout, let’s make sure you’ve got everything covered from the start. We’d love to help bring your vision to life—safely, smoothly, and with zero surprises.
