Ontario Building Code & HVAC: 2025 Updates Property Managers Can’t Ignore

Why this matters now

Ontario’s new Building Code (the 2024 OBC) came into effect on January 1, 2025, with a three-month transition window (to March 31, 2025) granted for certain in-progress designs. After that, all new permit applications must be to the 2024 Code.

The 2024 edition is the province’s most extensive harmonization with the 2020 National Building Code to date, removing approximately 1,730 technical differences, reducing surprises when working across jurisdictions or with national design teams.

Key HVAC changes that you’ll actually feel in operations

1) Ventilation now ties directly to ASHRAE 62.1

For most buildings, the need to provide outdoor air is now tied to one of ASHRAE 62.1’s three recognized procedures (Ventilation Rate, IAQ, or Natural Ventilation) and exhaust ventilation must meet Section 6.5 of ASHRAE 62.1, with some specific exceptions for storage/repair garages.

What to do: Ask your designer to specifically call out the section of 62.1 used for each space type and any exceptions granted for that space.

2) Explicit drain-pan coverage

The Code’s drain pan rule in Article 6.3.2.2 now explicitly covers HVAC that generates condensate or otherwise introduces liquid water into the air-stream, clarified in the explanatory materials that came with the 2024 edition’s Part 6.

What to do: Include checks for pans and overflows on cooling coils, DX units, DOAS, fan-coils and any evaporative cooling equipment during PMs and verify clear routing to a drain.

3) Fire & life-safety provisions for ducts were reorganized

The relevant Part 6 content has been renumbered and relocated to more closely align with the NBC. Several air-duct and plenum fire-safety provisions have been moved to Division B, Part 3 (Subsection 3.6.5), important to know when you’re reviewing those drawing/spec sections.

What to do: If you see fire ratings, dampers, linings or penetrations being referenced on drawings, confirm they reference the new Part 3 citations rather than the legacy Part 6 numbering.

4) Clear contaminant limits for garages

Where applicable, the Code now sets maximum concentrations for contaminants (e.g., CO ≤ 100 ppm; NO₂ ≤ 3 ppm where diesel vehicles predominate) and more explicitly ties garage ventilation to ASHRAE 62.1.

What to do: Verify sensor set-points and BAS sequences align with those thresholds, and also with the selected 62.1 procedure.

5) Additional safety/comfort notes that touch HVAC

Several of the municipality guidance summaries referenced below flag items property managers should be aware of when reviewing mechanical scopes, including the reduction of maximum surface temperature for exposed piping from 70 °C to 52 °C where there is possible human contact and broader Part 6 renumbering and relocation highlights. (Use these as navigation aids to the Code text itself.)

Project timing & permits

• In force date: O. Reg. 163/24 (2024 OBC) comes into force Jan 1, 2025 (now in effect)

• Transition period: Province confirms the grace period to Mar 31, 2025 for certain in-progress designs

• What to do: If a project bridged the transition, maintain a record of which edition is in play for each permit.

Adoption of innovative HVAC products (mid-2025 change)

Effective July 1, 2025, Ontario streamlined approval of innovative construction products that have been evaluated by the Canadian Construction Materials Centre (CCMC), i.e., no Minister’s Ruling is required for those evaluations, which should help for newer HVAC components.

What to do: If a vendor cites a CCMC evaluation, ask for the evaluation number and confirm its acceptance with your AHJ.

Practical checklist for property managers

1. Ask for an “OBC 2024 Part 6 compliance summary” in design submittals that call out ASHRAE 62.1 sections, drain-pan details, and any controls or setpoints for garages.

2. Confirm duct/liner fire references are pointed to the correct Part 3 – Subsection 3.6.5 in the new numbering.

3. Update PM inspections to explicitly include pan/drain checks and sensor set-points based on Code limits (above).

4. Document which Code edition applies to each permit started around Jan–Mar 2025.

5. If specifying new technology components, request CCMC evaluation details to take advantage of Ontario’s July 2025 streamlining for innovative products.

Sources

• Province of Ontario: 2024 Ontario Building Code overview and transition dates.

• Publications Ontario (Code Compendium): Division B, Part 6 ventilation requirements and ASHRAE 62.1 references; contaminant limits.

• Municipal technical bulletins (for navigation/context to the Code text): renumbering of Part 6 and relocation to Part 3

• HRAI: harmonization with National Code (approx. 1,730 differences removed)

• Ontario backgrounder / OBOA / ICC-ES: Minister’s Ruling streamlining effective July 1, 2025 tied to CCMC evaluations.

Ontario Building Code 2025: HVAC Requirements FAQ’s

1. Do I have to retrofit existing HVAC systems immediately?

No. The 2024 OBC applies only to new construction, additions and major renovations where building permits are required starting January 1, 2025 (transition period for permits granted until March 31, 2025). Nothing in the code forces existing building owners to retrofit HVAC systems unless the owner requests a building permit that subjects the work to the new rules.

2. My building has old fan-coils without drain pans. Do I need to retrofit them with pans?

Only if you are replacing, moving or modifying existing equipment subject to a permit after Jan 1, 2025. Article 6.3.2.2 of the OBC requires HVAC cooling coils, fan-coils, DX units and other equipment producing condensate or introducing water into the duct system to have drain pans or similar means to prevent dripping onto ceiling assemblies. Existing installations are “grandfathered” until the equipment is modified in some way.

3. How can I be sure my ventilation rates comply with ASHRAE 62.1?

The designer needs to first select the appropriate ventilation procedure recognized in ASHRAE 62.1 (Ventilation Rate, IAQ, or Natural Ventilation) and then document for each space what applies and why. Property managers should ask for a summary of ASHRAE 62.1 compliance in design reports. Designers should keep ventilation calculation reports.

4. How much ventilation is required for underground or enclosed parking garages?

Ventilation “shall be sufficient to prevent concentrations of air contaminants at any point from exceeding 100 ppm by volume for carbon monoxide (CO) and 3 ppm by volume for nitrogen dioxide (NO2) in parking garages used for diesel-powered vehicles,” as referenced in OBC. In other words, CO and NO₂ sensors and related control sequences need to be set to those limits.

5. Were the fire safety requirements for ducts and plenums changed?

Yes. Many requirements for duct and plenum construction materials and tests were transferred into Part 3 (Subsection 3.6.5) to harmonize the OBC with the National Code. If your drawings were developed years ago and still refer to the older numbering in Part 6 (Ducts and Plenums), ask your consultant to cross-reference the requirements and ensure all important provisions are still met.

6. Can I install innovative HVAC products not currently listed in the OBC?

Yes, new rules starting July 1, 2025 allow municipalities to accept products evaluated by the CCMC without a Minister’s Ruling. This should make it easier to install innovative HVAC equipment and materials that meet the performance objectives of the code.