What Started the Dunbar Construction Fire?

One balmy Tuesday last August, an apartment building under construction near Dunbar Street and West 41st Avenue went up in flames.

The fire started on the fifth floor and rapidly engulfed the six-storey project before leaping to the homes next door. A plume of fire and smoke rose as embers flew across Vancouver’s Dunbar-Southlands neighbourhood, damaging homes several blocks away. A tower crane collapsed and fell across 41st Avenue, toppling power lines and damaging one home. No deaths were reported.

Vancouver Fire Rescue Services Capt. Matthew Trudeau said in an email due to the extreme damage the exact source of ignition cannot be known for certain and fire investigators have deemed it an accident.

But The Tyee obtained a WorkSafeBC report that suggests the fire may have started because of fire hazards at the site including workers’ “improper spray foam application” and friction burn from drilling.

The construction site on the 3400-block of West 41st Avenue is slated to be a 114-unit market rental building. The owner, Sightline Properties, did not respond to requests for comment.

According to the WorkSafeBC report, construction company Graham Construction and Engineering Inc. was working on the development on Aug. 6, the day of the fire. The company also did not respond to requests for comment.

The WorkSafeBC report, which does not list an author, says the Vancouver Police Department investigated the fire and ruled out arson.

It says bolts from the crane were tested and indicated it collapsed because it was exposed to the fire’s heat. According to the report, it’s not likely the crane collapsed due to any defect.

Vancouver firefighters say because of unsafe conditions, their own investigation relied on interviews with workers and photos and video collected from the scene.

The WorkSafeBC report says the fire service narrowed the origin of the fire down to the fifth floor and offered three theories on the fire’s origins and spread.

A box in Suite 510

The report says the contents of a box in Suite 510 may have contributed to the fire’s rapid spread. It did not disclose exactly what was in the box.

“Presently this box is only a point of interest and would need to be further studied to rule out cause or involvement,” the report said, adding the box and its contents were stored in a suite next to the crane.

A chemical reaction from spray foam

The report said an “unqualified, noncertified employee” may have improperly applied spray foam insulation, causing a chemical reaction that started the fire.

The spray foam insulation used at the site is made by mixing two liquid components, according to the report. It said the liquids react quickly when mixed to create a foam that insulates, seals gaps and can form moisture and vapour barriers.

The chemical reaction when they mix generates heat. The report added if one of the foam’s liquid components — methylene diphenyl diisocyanate — comes into contact with water, it could trigger a violent reaction leading to explosion and fire.

The report that said according to the foam’s supplier, it’s critical the foam is applied to a maximum thickness of five centimetres to avoid the risk of fire. According to the report, the company did have a worker who was a certified spray foam applicator.

“It is to the understanding of this office [redacted] was a certified spray foam applicator,” WorkSafeBC said in the report. “However, [redacted] allowed another person, who was not certified, that day to spray foam.”

The report said it cannot be established if the employee was supervised while applying the product.

Friction burn from drilling

The third possibility is the fire could have ignited while workers drilled holes, the report said. It’s not clear what the holes were for — WorkSafeBC redacted that information from the report.

However, the report said workers were drilling multiple holes in wood, one of which was nearly 50 centimetres deep.

The report said drilling can generate excessive heat through friction, which may cause wood shavings and dust collecting in the hole to ignite.

‘The onus is on them’

The WorkSafeBC report said the company did not identify either the spray foam or drilling work as fire hazards and did not require employees to classify either job as “hot work” — defined by the Canadian Centre for Occupational Health and Safety as any job that generates heat, or can start a fire or explosion.

The term often refers to tasks like welding, grinding or burning, but can apply to any activity that generates enough heat to start a fire.

Vancouver building and fire bylaws require contractors to submit fire plans to the city with provisions for hot work.

Contractors often require workers to get hot work permits before starting any job that could generate heat.

Vancouver Fire and Rescue Services' Trudeau said contractors or developers are responsible for submitting a fire safety plan outlining any hot work on a construction site.

But according to the report, the contractor did not require hot work permits for either of the jobs that may have started the fire.

“The onus is on them to make sure that their fire safety plan is robust and all their construction practices, including any forms of work that could be classified as hot work, are safe,” Trudeau said.

WorkSafeBC said in the report it cannot accept or reject firefighters’ theories as to how the fire happened.

It said it’s up to its prevention team to determine if proper procedures were followed and follow up with any potential penalties.