Returning blaze at Toronto high-rises resulted from saw on concrete sparks

The first fire on Nov. 27 went on for two weeks and it was Jan. 4 before most residents could return to their units

Published May 05, 2026  •  Last updated 4 hours ago  •  2 minute read

A fire truck at the scene of a blaze in Thorncliffe Park last year. Photo by Jack Boland /Toronto Sun

Toronto Fire Chief Jim Jessop says the blaze that erupted between two east end condo high-rises for a second time on Monday – the scene of a weeks-long fire in between the buildings’ walls last winter – was caused by a saw creating sparks on the concrete.

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“The investigation has been completed,” said Jessop at a Tuesday morning press conference.

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“The fire was caused by workers in the building doing remedial work and repair work and restoration work from the original fire in the unit on the seventh floor. It was caused by sparks from a saw cutting into concrete that caused the TenTest insulation (a rigid, natural wood fiber) to again catch fire.”

Jessop told reporters that Toronto Fire responded to 11 Thorncliffe Park Drive and 21 Overlea Boulevard’s 3-alarm blaze on Tuesday morning with 12 trucks and over 100 firefighters and are still waiting to totally extinguish the blaze without any tenant evacuation necessary on either day.

“We have been continually monitoring the air in the building for both smoke and carbon monoxide and because it is safe to do so we have no intention of disrupting the (residents’) lives at this point, especially given what they went through at the end of 2025,” said the fire chief.

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“I can’t even manage the angst and the questions they have and the uncertainty and we’re going to do our best today to make sure that we bring as much certainty and honesty as we can. I’m happy to report there were no injuries. ”

Two building permits were issued by city of Toronto for remedial work

Kamal Gogna, the chief building official and executive director of Toronto Building, told reporters the city of Toronto issued two building permits for remedial work as a result of the 2025 fire but has now ordered all work to stop immediately.

“The scope of that work includes the removal of the TenTest material that the chief described as well as filling the gap with fire-stopping material along with some restoration of concrete work that is necessary,” said Gogna.

He added Toronto Building has issued an order to the property management requiring their engineer to produce a construction management plan prior to any work resuming on site.

“Work will not continue until we’re satisfied, the city is satisfied, that that remedial work can continue in safe manner,” said Gogna.

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He said he was aware that saws were being used to cut concrete in the remedial work “but there was a plan in place to address the situation with respect to the methodology that was going to be used.”

Gogna said TenTest insulation is commonly used to separate two structures in the construction industry.

“At the time when these buildings were constructed there were no code deficiencies identified,” he said.

Roughly 400 units were evacuated after the Nov. 27, 2025, fire, which continued for more than two weeks and most residents were not allowed back into their units until Jan. 4.

Jessop said at the time it was the most complex situation he had ever seen in his 30 years on the job because of the difficulty crews had accessing the smoldering insulation.

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