The Key Distinction: Change of Use
Fitting out a commercial space is not the same as renovating one. Under the Ontario Building Code, taking a unit from one use to another — a former retail space becoming a restaurant, an office becoming a clinic — is a change of use. And change of use triggers a full compliance review against the requirements for the new occupancy, not just approval of the work you're doing.
This is the single most common source of surprise in commercial fit-outs. A tenant budgets for a cosmetic renovation and discovers the application triggers requirements for exiting, fire separation, accessibility, and sometimes structural work — because the building has to comply as though it were being used that way from the start.
Part 3 vs Part 9 for Commercial Space
Most commercial fit-outs fall under Part 3 of the Building Code, which brings a deeper set of requirements than the Part 9 provisions that govern houses and small buildings. Part 3 addresses:
- Occupant load calculations — how many people the space can hold, which in turn governs exiting capacity, washroom counts, and egress width.
- Exiting requirements — number of exits, travel distance, and exit width, all derived from the occupant load and the floor area being served.
- Fire separations and ratings — separation between your unit and adjacent occupancies, and between occupancies of different hazard levels.
- Accessibility — barrier-free design under the Accessibility for Ontarians with Disabilities Act and the Code's own requirements.
- Fire protection systems — sprinklers, alarms, and their coverage relative to the new layout.
“Occupant load is the number that drives everything else. Get it wrong at the start and the exiting, washrooms, and egress design are all wrong with it.”
Approvals Beyond the Building Permit
A commercial fit-out is almost never just a building permit. Depending on the use, expect additional approval streams running in parallel:
Health unit approval (food service)
Restaurants, cafés, and any food handling operation require public health approval, covering food preparation surfaces, handwashing, dishwashing, refrigeration, and waste. This runs on its own timeline and is a common cause of opening delays.
Zoning and parking compliance
The proposed use has to be permitted in that zone. Parking requirements are often use-specific, and a change of use can create a parking deficiency that requires a variance — a separate application with its own timeline.
Liquor licensing (where applicable)
If alcohol is served, AGCO licensing adds a further approval layer, including requirements around the licensed area and separation from other uses.
Fire department review
Many municipalities route commercial fit-out applications through fire review as part of the permit process. Fire routes, hydrant access, and alarm system changes can all be examined.
What the Drawing Package Includes
A commercial fit-out submission is a coordinated set. Typically:
- Architectural drawings — floor plans with the new layout, partitions, door swings, and finishes; reflected ceiling plans; and interior elevations where relevant.
- Occupant load and life safety plans — showing the calculated load, exits, travel distances, and fire separation locations.
- Structural drawings, sealed by a P.Eng. — required whenever the fit-out involves new openings in floors or walls, adding rooftop equipment, mezzanines, changes to structural framing, or any significant added load.
- Mechanical, electrical, and plumbing drawings — coordinated with the architectural layout and reviewed against the base building's capacity.
- Accessibility compliance — dimensioned to barrier-free requirements.
- Schedule 1 design registration — confirming the drawings were prepared by a qualified designer.
Realistic Timelines
| Fit-Out Type | Permit Review | Key Driver |
|---|---|---|
| Office fit-out, no structural | 6–10 weeks | Straightforward if exiting and accessibility are already compliant |
| Retail, same use | 4–8 weeks | Simplest case — limited change of use implications |
| Retail to restaurant | 10–16 weeks | Change of use, occupant load, health unit, ventilation, grease |
| Medical or dental clinic | 10–16 weeks | Occupancy, barrier-free requirements, plumbing and medical gases |
| Fitness or assembly space | 10–18 weeks | High occupant load drives exiting, washrooms, and egress width |
| Any fit-out with structural change | Add 3–6 weeks | Sealed structural drawings and, often, deeper plan review |
Assumes a complete first submission. Runs in parallel with health unit and licensing where applicable.
Where Engineering Fits In
Many fit-outs proceed with architectural drawings alone. Engineering becomes necessary when the work touches the structure — and in commercial space that happens more often than tenants expect:
- New openings in a floor slab or a structural wall, for stairs, a service lift, or a pass-through.
- Rooftop equipment — HVAC units, exhaust fans, and kitchen hoods add concentrated loads, and their support often needs engineered design and curbing details.
- Mezzanines — adding a mezzanine almost always involves both structural design and code review of the new area's exiting and fire separation.
- Heavy equipment or storage — commercial kitchens, compactors, and racked storage all impose loads the base building may not have been designed for.
- Base building capacity questions — the live load a floor was designed for, and whether your use fits within it.
Our post on the commercial permit process in Ontario covers the broader submission flow, and the 2024 Building Code changes outline the current compliance requirements your drawings need to reflect.
Commercial Fit-Outs Across the GTA
Review practice, timelines, and local requirements vary by municipality. Find your city:
May Engineering Inc: Commercial Fit-Out Packages
May Engineering Inc prepares complete commercial fit-out submissions — architectural drawings, occupant load and life safety plans, and P.Eng.-sealed structural drawings for openings, rooftop equipment, and mezzanines. We coordinate the drawing set so the architectural, structural, and life safety components reconcile, which is what keeps a commercial file moving through review.
Taking on a commercial space? Send us the unit details and your intended use — we'll tell you what the fit-out will require before you commit to a lease.
Planning a commercial fit-out?
Free initial consultation. Complete permit packages for restaurants, retail, offices, and clinics across Ontario.