Dorchester fire
A fire broke out at a Dorchester apartment building still under construction. Photo: Boston Fire Department

A 6-alarm fire broke out Wednesday afternoon at a Dorchester condo building that was still under construction.

Boston firefighters are still at the scene Thursday handling hot spots on top of the building, Boston Fire Department Commissioner Joseph Finn said at a Thursday news conference.

The blaze broke out around 2:30 p.m. Wednesday at 1977 Dorchester Ave., the site of an 83-unit apartment building. Firefighters were on site for more than 16 hours.

“This was a very difficult fire for us last night,” Finn said. “Within nine minutes of the first arriving companies, who are less than a mile away, the roof started to sag and cave in.”


Finn said that crews were able to evacuate everyone, including construction personnel. The cause of the fire is not yet known. The department is investigating the cause and will also look at whether the sprinkler system was off-line or if it had failed.

Residents who purchased condos in the 83-unit building were reportedly preparing to move in next month. The building’s fire alarm system was scheduled to be inspected on Thursday, the last inspection to ensure that the building was move-in ready, officials said.

“The building met all state building requirements,” Finn said. “They’re probably more dangerous in the construction phase than they are when fully constructed and all fire prevention systems are operational.”

Though the building was up to code, Finn said that the smaller lumber used to construct the six-story building posed a hazard. Smaller lumber (such as 2-by-4 wood) catches fire more quickly than larger dimension lumber, which is inherently more fire-resistant.

Finn also noted that the residential building was of lightweight construction, whereas commercial buildings often use iron or steel instead of wood.

The fire consumed the top floor as well as the space between the ceiling and roof, where many of the building’s mechanical functions were housed, Finn said.

“That’s what triggered the collapse,” he said. “And what that did is buried [the fire] in debris, which is tough for us to access.”

The department used foam to fight those hidden, stubborn flames Wednesday night. Finn said the foam had a “tremendous outcome.”

It’s not yet known if the building will need to be knocked down completely. Mayor Marty Walsh was on scene Thursday morning and said that the city will work with anyone planning to move into the units who may now be displaced.

“We’re seeing more and more of this type of construction going on in the city of Boston,” he said. "I feel bad for this folks, many of the units were sold or rented."

More than 125 firefighters responded to the blaze. Though a “collapse zone” was established around the building, Finn said that he is “relatively comfortable” that it will not collapse. 

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