Date of Publication: June 8, 2026 [2023.22.V-02.C]
Subject: Permission to use Air Admittance Valves 2024 OBC UPDATE
2024 Ontario Building Code [O.Reg 163/24 Amended to 5/25] Reference(s):
Article 7.2.10.16. of Div. B
Subsection 7.5.9.of Div. B
Article 7.5.5.5. of Div. B
Summary of Changes: Editorial only.
Incoming Request:
When considering Sentence 7.5.9.2.(1)(b), when would it be considered “not practical” to connect to a vent?
Executive Summary:
Air admittance valves are permitted by the code, based on how “practical” it is to connect to a vent system, and at the discretion of the Authority Having Jurisdiction (AHJ). It is suggested that AHJ’s develop an internal guideline for consistent enforcement.
Considerations:
In a building undergoing renovation, sentence 7.5.9.1.(1) permits connection to an air admittance valve (AAV) in lieu of connecting to a vent system where it is “not practical” to connect to a vent system. Articles 7.5.9.2. and 7.5.9.3. describe conditions and limitations. The code does not provide any examples or appendix notes on what is considered “not practical”. It should be kept in mind that depending on the age of the building, Article 7.5.5.2. may be in effect, and a future vent connection should have been provided in every storey of a building. Also, it is the constructor’s responsibility to demonstrate that a vent connection is impractical.
Ideally an AHJ will have a guideline or policy to direct staff that takes the following into account:
- Have documented efforts been made to find a suitable connection for the vent?
- Is a new roof penetration required?
- Do finishes need to be removed to connect to an existing vent?
- Are there actual construction difficulties in connecting to a vent?
- Is the cost to connect to a vent significant in relation to the entire project?
- Has the property owner and/or designer been involved in the decision to install an AAV?
- Can all of the OBC and manufacturer’s requirements be met with an AAV installation?
Risk/Benefit Analysis:
The function of a connection to a vent system is to ensure that trap seals remain in place during fixture use. Approved AAV’s, installed in accordance with manufacturer’s instructions, have been shown to be effective. Use of an AAV may carry a slight additional risk since it is a mechanical device that may be tampered with or malfunction, however proper installation should mitigate this risk.
The bigger risk in application of this article is inconsistency from project to project or AHJ to AHJ and subsequent confusion among building officials and the public. This risk can be mitigated through a consistent enforcement of Subsection 7.5.9.
Final Recommendation(s):
AHJs should consider a written policy for conditions under which an AAV is permitted to be installed in lieu of connection to a vent system.
Recommendation to Ministry of Municipal Affairs and Housing:
None.
Referenced Documents:
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.