Firefighters and fire chiefs: Forget everything you know about wood construction. Tall wood buildings (TWB)—or more accurately tall mass timber buildings—are not the conventional, lightweight wood, stick-built construction with which the fire service is familiar. There are no individual 2 x 4s, I-joists or open web trusses. In fact, there is no dimensional lumber or conventional lightweight wood products of any kind in tall mass timber buildings.
There are 14 proposals before the International Code Council (ICC) to incorporate TWB code restrictions into the International Building Code (IBC). These code provisions introduce three new construction types—Type IV-A, -B and -C. They also outline standards for the manufacture of mass timber, height and area restrictions, enhanced fire protection (both active and passive), fire safety during construction, water supply requirements, standards on sealants and adhesives, non-combustible protection, and fire-resistance ratings of tall mass timber.
After consultation with its membership, the ICC board of directors saw a need to create an ad hoc committee to study the fire safety implications of tall combustible buildings. After two years of study, discussion, testing and analysis, the committee concluded that the proposals recommended would provide life safety protections to the public and first responders that are equal to or greater than tall buildings that are made of steel or concrete.
Image Credit: American Wood Council