Project contact is Kuma Sumathipala at the American Wood Council
Summary
The United States has a vast supply of forest biomass, which provides an abundant resource suitable for the manufacturing of mass timber products. Recent research has shown that these mass timber products can be safely implemented in tall buildings. In 2018 and 2019, this research led to changes allowing the construction of 18 story buildings with mass timber structures in the 2021 International Building Code (IBC). Although this development has created opportunities, it does not respond to recent architectural trends, as the new regulations do not allow for visible mass timber in buildings exceeding 12 stories in height and only allow for limited areas of visible Cross Laminated Timber (CLT) surface in buildings from 9 to 12 stories in height.
The strict limitation on the area of visible mass timber in 2021 IBC was based partially on fire performance of CLT manufactured to an earlier edition (2012) of ANSI/APA PRG 320. New adhesive qualification requirements in the 2018 standard have significantly improved the fire performance of CLT. This improved fire performance represents an opportunity to justify increases to code-prescribed limits on exposed mass timber areas which would respond to current, and likely future, architectural aesthetic demands, allowing for an expansion of the market for tall mass timber buildings.
In order to justify these increases in allowable exposed mass timber areas, compartment fire tests will be designed and performed to demonstrate that the fire performance of increased exposed mass timber surfaces are consistent with the (newly-recognized) International Building Code safety criterion. In addition, fire safe solutions for the intersections between exposed mass timber members and restoration of fire-damaged exposed mass timber are needed to be developed and tested. Test results and other findings will be used to develop and justify new requirements for U.S. model building codes, thereby enabling more innovative utilization of renewable U.S. forest resources in construction.
Developed by ICC and American Wood Council, this first edition provides an overview of requirements for mass timber construction as found in the 2021 International Building Code® (IBC®). The document reviews the 2015 IBC’s recognition of cross-laminated timber (CLT), the reorganization of heavy timber provisions in the 2018 IBC, followed by the historic changes in the 2021 IBC and International Fire Code® (IFC®) for tall mass timber construction. The 2021 IBC and IFC include important changes in material technologies and their expanded use as proposed by the ICC Ad Hoc Committee on Tall Wood Buildings. Three new types of construction (Types IV-A, IV-B and IV-C) defined and included in the 2021 codes allow the use of mass timber for buildings of taller heights, more stories above grade, and greater allowable areas compared to existing provisions for heavy timber buildings.
Features:
More than 100 full-color photos, illustrations and tables enhance comprehension and help users visualize requirements
Content accurately reflects mass timber provisions in the 2015, 2018 and 2021 IBC, and 2021 IFC
“Change Significance” topics reinforce the content and offer helpful background regarding code provisions
Results are provided for five fire tests in a fully furnished structure constructed to simulate Types IV-A, IV-B and IV-C
Detailed examples facilitate comprehension of code application and methods of determining code compliance
Application of energy, sound transmission, structural loads, and other code provisions to mass timber construction
50 practice questions to help users prepare for ICC certification exams
This is an incredibly valuable and time-saving reference for architects, engineers, building/fire officials and inspectors.
