• What is the difference between a party wall and firewall?

  QAI: A wall separating two adjoining buildings, each of which is capable of being a separate real-estate entity, can be described as a party wall or a firewall. However, contrary to a party wall, a firewall used to subdivide a building, or separate adjoining buildings has the capability to resist the spread of fire and has structural stability to remain intact under fire conditions for the required fire-rated time. A firewall is constructed with non-combustible materials that has a fire resistance rating as prescribed in the Code and extends from the ground continuously through all storeys of a building or buildings. Both are defined terms in Article 1.4.1.2 division A of the Building Code.

• When is it a firewall and when is it a party wall?

QAI: Any party wall on a property line shall be constructed as a firewall except for buildings of residential occupancy as described in Article 9.10.1.2. It states that when there is no dwelling unit above another dwelling unit, a party wall on the properly line need not be constructed as a firewall, provided it is constructed as a fire separation having not less than a 1-hr fire resistance rating.

• Does the design require P. Eng. to sign off?

QAI: Where firewalls are used, the requirements in Part 3 shall apply and the design shall be signed off by a registered professional. Professional engineers and registered architects are considered as registered professionals. For Part 9 structures firewalls may be designed and built per Appendix D, or as tested to ULC S101, or as designed by a P. Eng. For engineered structures, the firewalls may be designed and built per Appendix D or as tested to ULC S101; however, an engineer takes responsibility for design and construction of the building including the firewalls. The manufacturer would first need to determine if a firewall is required for their project. If a firewall is needed, the design would need to comply with Part 3 and depending on the occupancy type, the fire-resistance rating of the firewall may vary. All firewalls shall be of non-combustible construction and may be designed and built per Appendix D, or as tested to ULC S101, or as designed by a P. Eng. Please contact QAI, fbsadmin@qai.org, to learn more about how to approve your firewall assembly to “ULC S101 Standard Methods of Fire Endurance Tests of Building Construction and Materials”.