Cause remains unknown. Builders using engieneered lumber should read APA Guidelines for fire-ratings.
Similar fires in Dorchester and Waltham may have been accelerated by engineered lumber. Both sites were under construction and are now total losses.
The Dorchester fire began on June 28 as a result of a generator’s exhaust duct being placed three inches from combustible materials. The minimum safe distance was one foot. The engineered lumber I-beams were covered in sheetrock to reduce burn rate, but to little effect. The roof had sagged within nine minutes of the fire department’s arrival.
The cause of the Waltham fire on July 23 has not been determined. Officials have asked for information or imagery of the early stages of the fire.
Both fires were massive by modern standards. The Dorchester fire required 125 firefighters and took all night to control. The Waltham fire drew response from twelve communities. Eight trucks remained the following day to soak the smoldering site.
Counting both fires, a combined 343 residential units were destroyed.
According to a CBS I-Team report, engineered lumber is now being used where steel I-beams would have been used prior to a 2009 code change.
Waltham City Council Vice President Robert Logan has said we should reinstate the requirement for steel frame.
Engineered lumber is a wood-chip composite material shaped into an I-beam or other cross-sections for great strength relative to weight and cost.
APA, The Engineered Wood Association, operates a testing facility in Atlanta, Georgia and sells a $3 guide to fire-rated systems. All contractors and builders should understand the safe uses of engineered lumber and the risk of fire during construction.