Ontario Building Code Chimney Lining Standards | empcontracting.ca Inc.
Sarah's Expert Insight
OBC Compliance Specialist
"In heritage-rich areas like London and Oakville, or for custom builds in Muskoka, the transition between masonry and lining is where most fire safety failures occur. At empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize the 1100°C thermal resistance requirement for clay liners to ensure that modern heating demands don't compromise the safety of your home’s structural envelope."
Compliance with OBC 2024: Chimney Flues and Lining Requirements
Ensuring your masonry or concrete chimney meets the strict requirements of the 2024 Ontario Building Code (OBC) is essential for fire safety and structural longevity. Whether you are building a new residence or renovating an existing property, empcontracting.ca Inc. your construction contractor in London, Ontario, provides expert guidance on these critical safety standards.
9.21.2.6. Oval Chimney Flues
According to the OBC, the dimensions of oval chimney flues must be carefully controlled. The width of an oval chimney flue shall not be less than two-thirds of its breadth to ensure proper airflow and venting efficiency.
9.21.3.1. to 9.21.3.2. Mandatory Lining and Joint Integrity
Every masonry or concrete chimney is required to have a dedicated lining made of clay, concrete, firebrick, or metal. Key installation factors include:
- Sealing: Joints must be sealed to create a complete barrier against flue gases and condensate.
- Smoothness: For clay, concrete, or firebrick, joints must be struck flush to ensure a straight, smooth, and aligned flue path.
9.21.3.3. to 9.21.3.6. Approved Lining Materials
The OBC specifies rigorous material standards for different liner types:
- Clay Liners: Must conform to CAN/CSA-A324-M, be at least 15.9 mm thick, and resist temperatures up to 1100°C.
- Firebrick Liners: Must meet ASTM C27 standards and be laid with high-temperature air-setting refractory mortar.
- Concrete Liners: Must comply with CAN/CSA-A405-M for masonry chimneys.
- Metal Liners: Must be constructed of at least 0.3 mm thick stainless steel. These are generally restricted to gas- or oil-burning appliances unless otherwise specified.
9.21.3.7. Installation Timing
A critical compliance factor is that chimney liners must be installed simultaneously as the surrounding masonry or concrete is placed to ensure structural unity.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.