Hot work law, codes and standards in Canada

Hot work in Canada is governed by two overlapping sets of rules. Fire codes, enforced by fire marshals and local fire departments, protect buildings and the people in them. Occupational health and safety law, enforced by provincial, territorial and federal OHS regulators, protects workers. A welding job in a factory is covered by both. On top of the law sit consensus standards, especially CSA W117.2, which many regulations adopt by reference, and the requirements of insurers and owners. This lesson maps the framework so you know where each requirement comes from.

Fire codes: the National Fire Code and provincial codes

The National Fire Code of Canada (NFC) is a model code published by the National Research Council. Provinces and territories adopt it, sometimes with changes, or publish their own code based on it. Section 5.2 of Division B, Hot Works, applies to cutting, welding, soldering, brazing, grinding, adhesive bonding, thermal spraying, thawing pipes, torch-applied roofing and similar work. It requires hot work to be done by trained people, requires equipment to be examined for leaks and defects before each use, and requires hot work to conform to CSA W117.2 except where the code says otherwise.

Where hot work cannot be done in an area free of combustibles, the code requires precautions: combustible and flammable materials within 15 m of the work must be protected, a continuous fire watch must be maintained during the work and for at least 60 minutes after it ends, and the area must be inspected again later, typically 4 hours after the work is finished, unless a more thorough inspection is done when the fire watch ends. At least one portable extinguisher must be available. Hot work on containers or piping that hold or held flammable or combustible substances is restricted until they have been made safe. Where a building needs a fire safety plan, the plan must include the hot work precautions.

Each province enforces its own version. The Ontario Fire Code (O. Reg. 213/07) contains its own Section 5.2 based on the NFC. British Columbia, Alberta, Quebec and the other provinces and territories adopt the NFC with amendments; a few large cities have their own bylaws. The 2025 edition of the National Fire Code was published in late 2025, and provinces adopt new editions on their own schedules, so always check which edition applies where you work.

Occupational health and safety law

Every province and territory, and the federal government for federally regulated workplaces, has OHS regulations covering welding and hot work. The details vary, but common themes appear across the country: testing for flammable atmospheres before hot work, purging and cleaning containers, protecting nearby workers from arc flash, ventilation and local exhaust, respiratory protection, flashback arrestors on oxy-fuel equipment, fire extinguishers near the work and fire watches when combustibles are at risk.

• Ontario: the Industrial Establishments regulation (Reg. 851) requires hot processes in areas where explosive mixtures could form to be controlled, and the Construction Projects regulation (O. Reg. 213/91) has sections on cylinders, fire precautions during welding and cutting, and fire extinguishers.
• British Columbia: Part 12 of the OHS Regulation includes a division on welding, cutting and allied processes, covering local exhaust, removing hazardous coatings, testing vessels that may contain flammable substances, flame-resistant clothing, flashback arrestors, fire extinguishers and marking recently welded hot work.
• Alberta: the OHS Code requires a hot work permit or equivalent controls, removal or isolation of combustibles, and atmospheric testing showing flammable substances at or below a set fraction of the lower explosive limit, repeated at intervals.
• Federally regulated workplaces: the Canada Occupational Health and Safety Regulations prohibit hot work in a hazardous confined space where flammable substances exceed 10 % of the lower explosive limit or oxygen exceeds 23 %, unless a qualified person determines it is safe, and require a fire watch and emergency equipment.
• Manitoba, Saskatchewan, Quebec, the Atlantic provinces and the territories have similar sections, many referring to CSA W117.2, sometimes to an older edition.

OHS law also includes general duties. Employers must take every precaution reasonable in the circumstances to protect workers, supervisors must ensure workers follow safe procedures, and workers must use the protective equipment and follow the procedures. These general duties mean that following only the specific welding sections is not enough if a hazard remains.

CSA W117.2 and other standards

CSA W117.2, Safety in welding, cutting, and allied processes, is the main Canadian standard. The eighth edition, CSA W117.2:25, was published in 2025 and replaces the 2019 edition, which had been reaffirmed in 2023. Many regulations still refer to older editions such as W117.2-94, W117.2-06 or W117.2-12, so the edition that is legally binding can differ from the latest one. The standard covers fire prevention, protection of people, ventilation and fume control, gas cylinders and equipment, arc welding equipment and specific processes. Other standards that matter include CSA Z94.3 for eye and face protectors, including welding filter shades, CSA Z94.4 for respirators and the fire code's references to NFPA standards for some gases.

Insurers also publish hot work guidance. Many Canadian property insurers require a written permit system, a fire watch of 60 minutes or more, and final checks several hours after the work, and their conditions can be stricter than the code.

Welder qualification and other requirements

Welders in Canada are certified in the Red Seal and provincial trade systems, and companies that weld structural steel and other critical work must be certified by the Canadian Welding Bureau (CWB) to CSA W47.1 or related standards. These qualifications are about weld quality, not fire prevention, but CSA W117.2 and the fire code both require hot work operators to be trained in the hazards and precautions. WHMIS applies to welding gases and consumables: labels, safety data sheets and worker training. Transportation of Dangerous Goods rules apply when cylinders are moved on public roads.

Due diligence

When a hot work fire or injury leads to charges, employers and supervisors can defend themselves by showing due diligence: that they took every reasonable precaution. In practice that means a written hot work program, trained people, permits that were actually completed with a real inspection of the area, fire watches that were posted and documented, equipment that was inspected, and supervisors who checked that the rules were followed. Paperwork alone is not due diligence; a permit signed without anyone looking at the area is evidence of the opposite.

Who enforces what, in practice

On a typical day, the people most likely to look at hot work are not fire marshals or OHS inspectors but supervisors, joint health and safety committee members, insurance inspectors and the owner's own maintenance or facilities staff. Fire inspectors usually become involved after a complaint, during routine inspections of buildings that need fire safety plans, or after a fire. OHS inspectors visit after injuries, complaints and during targeted campaigns, and they can issue orders to stop work, require precautions or produce documents such as permits and training records. Both kinds of inspector can lay charges, and courts have imposed large fines on employers and supervisors after hot work fires and explosions.

Joint health and safety committees and health and safety representatives have a useful role. They can inspect hot work areas, review permits and training records, and make written recommendations to the employer, who must respond. Workers also have the right to refuse unsafe work, which includes refusing to do hot work in an area that has not been prepared, or to act as a fire watch without training or an extinguisher.

Reading a requirement correctly

Hot work rules are short, and small words matter. A requirement that a fire watch be maintained for at least a set time means that time is a minimum, not a target. A requirement that combustibles be protected within a distance means everything inside that distance, in every direction, including above and below. Where a rule says an extinguisher must be available, it means within immediate reach of the work, charged and of the right type, not somewhere in the building. When in doubt, read the rule with its purpose in mind: to stop a spark from becoming a fire, and a fire from becoming a disaster.

Many organizations summarize the legal requirements in a one-page table inside their hot work program, listing each rule, its source and how the site meets it. That table is useful for training, audits and showing inspectors how the program meets the law, and it should be updated whenever codes, standards or regulations change.