Thorncliffe Park high-rise fire enters fifth day: hidden wall blaze, CO hazards, and when residents might return

A stubborn five-alarm fire in Toronto’s Thorncliffe Park has stretched into a fifth day, with officials warning there is still no firm timeline for full extinguishment or for hundreds of displaced residents to return home. The fire, which began around 1:30 p.m. on Thursday, November 27, started at 11 Thorncliffe Park Drive and migrated through concealed spaces to the adjoining tower at 21 Overlea Boulevard, forcing evacuations across more than 400 units.

Why the Thorncliffe Park fire is so hard to put out

Fire officials describe a rare, “slow-burn” scenario: the blaze is smouldering inside wall cavities, feeding on combustible sheathing and insulation. Because the heat source is trapped between layers of concrete and other materials, crews can’t always see flames directly; they rely on thermal readings, targeted demolition, and continuous air monitoring. The incident commander called it one of the most complex high-rise fires they’ve encountered in decades.

Key challenges:

• Concealed spread: Fire “creeps” vertically and laterally behind walls, demanding painstaking open-up work.

• Air quality risks: Early in the response, life-threatening carbon monoxide levels were detected in portions of the complex; readings have improved but require constant checks.

• Structural access: Crews must balance aggressive suppression with building safety when opening shafts, chases, and interstitial spaces.

Evacuations, support, and what displaced residents should know

• Who’s affected: Residents from both towers remain out while suppression and ventilation continue. Authorities have emphasized that re-entry won’t occur until air quality is stable and hot spots are eliminated.

• Support on the ground: Emergency partners have arranged temporary accommodations, meals, and essentials for impacted households. If you have not registered, contact the city’s assistance line or on-site reception staff posted near the complex; they can help with lodging, medication needs, and pet considerations.

• Document access: Limited, escorted retrievals for critical items (IDs, medications) have been facilitated at times; availability depends on safety conditions and may change without notice. Bring photo ID and be prepared for waiting periods.

Timeline at a glance

• Thu, Nov 27 (afternoon): Initial calls report smoke on multiple floors at 11 Thorncliffe Park Dr. Firefighters discover concealed fire; response escalates.

• Thu evening–Fri: Fire found spreading within inter-wall spaces and into 21 Overlea Blvd. Full evacuations ordered; CO levels spike in affected areas.

• Sat–Sun: Continuous suppression, ventilation, and selective demolition. Displaced residents enter day 3–4 away from home.

• Mon, Dec 1: Officials say the fire remains active but contained to concealed areas; progress described as “positive,” yet no return timeline is provided.

Note: Dates above reflect local Toronto time.

What crews are doing today

• Targeted open-ups: Carefully removing sections of wall/soffit to chase heat signatures.

• Air management: Deploying high-capacity fans and monitoring for CO and other combustion byproducts on a rolling schedule.

• Fire watch: Rotating companies to maintain 24/7 coverage, with rapid response if temperatures climb in newly exposed cavities.

• Engineering consults: Working alongside building and structural engineers to plan safe access routes and protect load-bearing components.

Safety guidance for residents and nearby community

• Do not enter the buildings until authorities declare re-occupancy; CO can accumulate even when smoke isn’t visible.

• Medication & essentials: If you missed a retrieval window, ask reception staff about the next escorted access period; these are safety-dependent.

• Insurance & documentation: Photograph receipts for temporary lodging and necessities; contact your insurer and keep a log of displacement dates and communications.

• Well-being: Extended displacement is stressful. On-site teams can connect you with mental-health and social services; children and seniors may need extra support as the situation continues.

Questions we can answer now

Why can’t sprinklers stop it? Sprinklers control open-area fires but hidden-space fires can bypass heads if flames and heat are insulated inside walls. Crews must physically access and cool those voids.

Is the building at risk of collapse? Officials have not signaled an imminent structural failure; however, they’re proceeding cautiously, opening only what’s necessary and re-checking integrity as they go.

When can people go home? There’s no set date. Even after suppression, expect time for air clearance, inspections, and utility checks before staged re-entry.

What’s next

Authorities plan additional updates once crews finish the latest round of open-ups and air tests. The critical markers to watch are stable near-zero CO readings, no residual heat in wall cavities, and cleared egress routes. Until then, residents should remain in contact with reception centers or assistance lines for housing, transportation, and case-management updates.