Date of Publication: January 22, 2026 [2026.01.V-01.C]
Subject: Requirement for Fire Alarm System in an Existing Building
2024 Ontario Building Code Reference(s):
Article 1.3.3.3C of Div. A.
Article 3.2.4.1 of Div. B
Subsection 11.4.3. of Div. B
Appendix note A-11.3.1.1.(1).
Incoming Request:
An application has been received for a tenant fit-out in an existing Part 3 building constructed under the 2012 OBC. The building is sprinklered and less than 5 years old. The proposed new occupancy is not considered a change in use or a reduction in performance level. Sentence 3.2.4.1.(1) of the 2024 OBC states that “a fire alarm system shall be installed in buildings in which an automatic sprinkler system is installed”. Is a fire alarm system required to be installed in this building?
Executive Summary:
Sentence 3.2.4.1.(1) is not intended as a blanket requirement for existing sprinklered buildings undergoing renovations.
Discussion & Considerations:
All of the proposed new construction (partitions, interior dimensions, HVAC, plumbing, etc.) will be subject to Part 3 of Div. B. As this example involves an existing building less than 5 years old, Part 11 is not initially applicable. However, per Article 1.3.3.3C., of Div. A, Section 3.18. must be consulted to determine if the proposed work is considered a change of use resulting in a reduction in performance level. If the analysis shows a reduction in performance level or a change in use, compensating construction may be required as described in Articles 11.4.3.1., 11.4.3.2., 11.4.3.4., 11.4.3.6. and 11.4.3.7. This may involve upgrading of fire separations or early warning systems, possibly including a fire alarm system.
If the proposed construction does not require compensating construction (per Section 3.18. for buildings less than 5 years old, and Section 11.4 for older than 5 years), and does not trigger a requirement for a fire alarm system due to the requirements of Sentences 3.2.4.1.(2) to (6), then a fire alarm system would generally not be required. This conclusion is based on 3 principles:
- Article 3.2.4.1.(1) of Div. B was not intended to act as a blanket requirement for every existing building that is sprinklered;
- Article 1.3.3.3C. of Div. A states that the Code applies only to the design and construction of the extensions and those parts of the building that are subject to the material alteration or repair, unless the existing systems are adversely affected; and
- Appendix Note A-11.3.1.1.(1) states that “after construction, the performance level of the building may remain the same, or be made better, but may not be made worse”.
Risk/Benefit Analysis:
The introduction of Sentence 3.2.4.1.(1) is intended to harmonize with the National Building Code, which emphasizes the important contribution of coordinated life safety systems (i.e. occupant notification and system monitoring) when active fire safety systems such as sprinklers are present in new construction. In an existing building undergoing renovation (regardless of age), there are existing Code provisions that require upgrading of life safety systems based on change of use and a reduction in performance level. Sentence 3.2.4.1.(1) was not intended to be applied to existing sprinklered buildings undergoing renovations. When evaluating the scope of work in an existing building, professional judgement, proportionality, and the general intent of Part 11 (which is to allow flexibility, but not reduce the performance level of the building) should inform the decisions.
Final Recommendation:
Sentence 3.2.4.1.(1) is generally not intended to be applied in a blanket fashion to existing sprinklered buildings undergoing renovation. However, a full 3.18 or Part 11 analysis of the proposed work must be completed to determine if other code provisions may trigger a fire alarm requirement.
Recommendation to Ministry of Municipal Affairs and Housing:
An Appendix Note clarifying the applicability of Sentence 3.2.4.1.(1). would be beneficial.
Referenced Document(s):
2024 Ontario Building Code O.Reg 163/24 Amended to 5/25
Disclaimer:
This guidance document is intended to assist building officials by gathering relevant information to interpret the OBC Act and the prescriptive requirements of the Ontario Building Code, and is intended to be a best practice aid for building officials.
The views expressed within this guidance document should not be considered as the official interpretation of legislated requirements based on the Ontario Building Code, as the final responsibility for interpretation rests with the local Authority Having Jurisdiction.
The views of this advisory committee should not be construed as legal advice.