Are you Renovating? Part 11 of the Ontario Building Code

If you are renovating your home or business there are some clauses in the Ontario Building Code(OBC) that you should know. These clauses are tucked way in the back of the OBC under Part 11: Renovations. The OBC is available online, it is updated about every 4 years and is the governing document for building construction in Ontario. It is based off of the National Building Code of Canada 2010 (NBC), the current latest revision of the NBC is 2015 (Ontario has not adopted it yet). There is no Part 11 for renovations in the NBC and it is unique to Ontario. The current revision of the OBC is 2012, and the code this article is based off of.

The great thing about OBC Part 11 is that, if your building or renovation qualifies, you can build under less stringent requirements than if you were doing new construction. You, or your contractor, may not even need a construction professional to sign off on the design. However, depending on your local municipality a building permit may be required.

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We can provide design, engineering and drafting for your renovation project.

Does Part 11 Apply?

If you are doing renovations to any building there are a few things you have to check before you can use the renovation clauses in the Ontario Building Code:

  1. Is the existing structure at least 5 years old?
  2. Are you keeping the current major occupancy of the building? IE not changing your house to retail space.
  3. Are you maintaining firefighter access?
  4. Are you maintaining the current performance level of the building? (See Below)

If you answered yes to all of these then you are eligible to use Part 11 of the OBC. Also of note, if a building is extended (i.e. you build an addition) the extension may be governed by all other parts of the building code and the existing building may be governed under Part 11.

A kitchen renovation under Part 11 of the OBC

Major Occupancy

Changing the major occupancy of a building has it’s own chapter in the OBC (Part 10) and can be difficult to interpret. As long as you aren’t changing how you are using the space then it’s okay to assume you can use Part 11. This gets especially difficult when considering multiple and prohibited combinations of occupancies of the same building. Otherwise you may want to consult a professional.

Building Systems

The building systems, i.e. the sprinklers, electricity, and plumbing are still required to be designed to the current code. Meaning your old nob and tube wiring cannot be extended into your addition, nor can your lead pipes be used for your bathroom renovation.

Performance Level

There are a number of criteria to maintain the performance level of the building. The performance level after construction cannot be less than the performance level prior to construction. If the performance level is reduced then compensating construction is required. The performance level is determined by a number of factors. Items that are considered reductions in performance level are:

  • Structural:
    • The major occupancy changes.
    • Occupant load increases by more than 15%, or
    • The live load (furniture, people, fixings, etc) increases due to the change within the same major occupancy.
    • The floor and roof framing is not adequate to support the new dead (weight) and live loads.
  • Increase in Occupant Load:
    • The new occupant load is increased by 15% or less and 15% above the requirements for which a fire alarm system is required under Part 3.
    • The new occupant load will be more than 15% above the exit capacity of the building as required under Part 3.
  • Change of Major Occupancy (Part 11)
    • Changing the major occupancy to a major occupancy with a greater hazard index.
    • Splitting an existing suite (Under Group C Occupancy).
    • Converting a suite to a gaming premises.
    • Converting a farm building or part of a farm building to a major occupancy.
    • Converting a building to a post disaster building.
    • Converting a building to a retirement home.
    • Changing a building to an indeterminate occupancy.
  • Fire Safety Requirements
    • Early warning and evacuation requirements are exceeded in the new major occupancy.
    • Fire separations and fire-resistance ratings are not conforming to the requirements for adjacent major occupancies.
    • Changing to a major occupancy that requires non-combustible construction.
    • A building more than 3 storeys in height without proper egress routes.
  • Plumbing and Sewage
    • Required plumbing is adversely affected by the extension, alteration or repair.
    • Adversely affecting the sewage system.
    • The total daily design sanitary sewage flow is exceeding the capacity of any part of the system.
  • Other Requirements
    • Increasing the number bedrooms in a dwelling unit.
    • Construction is more than 15% of the finished area of  a dwelling unit.
    • Adding new plumbing fixtures to a dwelling unit.
    • A building of combustible construction extends to more than four storeys in height.

A suite is defined as “a single room or series of rooms of complementary use, operated under a single tenancy, and includes, (a) dwelling units, (b) individual guest rooms in motels, hotels, boarding houses, rooming houses and dormitories, and (c) individual stores and individual or complementary rooms for business and personal services occupancies.”

A dwelling unit is defined as  a suite operated as a housekeeping unit, used or intended to be used as a domicile by one or more persons and usually containing cooking, eating, living, sleeping and sanitary facilities.”

Basic Renovations

If you are maintaining the performance level then construction may be carried on all or part of the existing building. The construction has to reuse, relocate or extend similar materials or components with the goal of retaining;

  • the existing character,
  • the structural uniqueness,
  • the heritage value, or
  • the aesthetic appearance.

However, the construction cannot adversely affect;

  • the early warning and evacuation systems,
  • fire separations,
  • structural adequacy, nor
  • create an unhealthy environment in the building.

Also of note, if you substantially remove and replace walls, ceilings, floor or roof assemblies of an existing building then the structure and fire resistance has to be upgraded to code. For example, while you are re-modelling your kitchen you come across an insufficient beam, then you will have to upgrade that beam to meet the current OBC. The rules are also different for suites and retirement homes. You may also be required to install sprinklers if your group occupancy requires it under other parts of the code.

Plumbing and Sewage Systems

As stated before Part 11 does not apply to plumbing and sewage systems. The new plumbing and sewage have to comply with Part 7 and Part 8 of the OBC. This includes extension, alteration or repair. When extending, altering or repairing your septic tank and lines you may not be able to put it in the same place if it is too close to the water table.

Compensating Construction

If any factors affecting the performance level of an extension, alteration or repair are reduced then compensating construction will be required. This only applies to the part of the building that is being altered. Depending on the factor that reduced the performance level, the compensating construction may be:

  • Structural
    • All new loads must be properly supported, or
    • The portion of the floor affected shall have restricted loading with posted signs.
  • Increase in Occupant Load
    • Early warning and evacuation signs will be upgraded to Part 11 (with some exceptions).
  • Change in Major Occupancy
    • Additional upgrades may be required to Part 11 so the construction index is equal to the hazard index.
    • Additional upgrades to Part 3 (Fire Protection), Part 6 (HVAC), and Part 9 (Small Buildings) of the Building Code.
  • Fire Safety Requirements
    • Upgrading fire separations to Part 3 and Part 11.
    • Constructed with noncombustible construction or sprinklered (on the floor subject to change).
    • Retirement homes will require sprinklers, voice communication systems, self closing doors.
  • Plumbing and Sewage
    • Upgrading the plumbing or sewage system in the existing building.


The Chief Building Official (CBO) in your municipality may not require the compensating construction and is allowed to do so under the OBC. The CBO can wave compensating construction if they’re satisfied that the construction is impractical because of structural difficulties, construction difficulties or it is detrimental to preserving a heritage building.


If you got this far with your new construction project and didn’t see any red flags then it is possible to carry out your renovation, alteration or repair under Part 11 of the building code. You may still require a building permit depending on your local government, however you may have less stringent requirements for the building permit. It is possible that you don’t need an engineer nor an architect to assist you in the planning and design of your project. If you are unsure the safest route is to consult with a professional about your project. Part 11 of the Ontario Building Code allows building owners some flexibility in maintaining the existing appeal of their property and to circumnavigate the updated requirements of the most recent Ontario Building Code.

1 Comment

  1. FINN ConstructionJune 12, 2019

    Great article to read when planning a home renovation.


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