The Boston building and fire commissioners Wednesday promised to look for ways to make large wood-frame buildings safer during construction, a time when they said the buildings are most vulnerable to fire.
Specifically, Boston Fire Commissioner Joseph Finn said lightweight engineered wood, which was used in the Dorchester Avenue apartment building that caught fire on June 28, poses a hazard to firefighters.
“I have concerns about the lightweight construction, as we’ve just witnessed,” Finn said at a press conference Wednesday morning. “Fire in these type of buildings develop very rapidly. They’re very dangerous when they do develop like that.”
Workers smelled smoke in the apartment building around 1 p.m. on June 28, just after returning from lunch, Finn said. They didn’t call the Fire Department until 2:30, giving the fire a big head start.
By the time firefighters arrived, the roof was on the verge of collapse.
“Nine minutes upon arrival of our companies and that roof collapsed on the southwest corner of the building, the point of origin,” Finn said.
Finn and Inspectional Services Commissioner William Christopher Jr. said members of their departments will meet to come up with recommendations to make the building process safer, as larger and taller wood-frame structures continue to spring up in and all around Boston.
Both Finn and Christopher stressed that wood structures, including those using lightweight engineered wood, are safe once fire suppression systems, like sprinklers and fire-rated drywall, are in place. But construction poses different risks because those systems are not in place, and exposed wood has plenty of oxygen available to burn.
Christopher said he does not intend to push for a change to the building code to prevent certain materials from being used or to reduce the square-footage of buildings that can be constructed with wood.
“This is more about the process during construction when the building is in its most unprotected state,” he said.
Christopher said the structure met the required building codes. The sprinkler system was operational, but not yet activated. It was scheduled for a final inspection on June 29, the next day. During that inspection, the sprinklers would have been pressurized and tested.
The NBC Boston Investigators have been looking into lightweight engineered wood for a month, prompted by that Dorchester fire.
The material is made like plywood, where small wood chips are glued and pressed together. Beams are made with several layers of that pressed together. I-beams are comprised of plywood between two runners of dimensional lumber.
Expert tests and several studies show that the plywood portion of the I-beams, which are used in the floor and ceiling structure, burn through three times faster than dimensional lumber. That leads to a faster structural failure than floors and ceilings supported by dimensional lumber.