The U.S. Army Corps of Engineers announced Sept. 23 a new policy requiring the consideration of mass timber as a structural option for all vertical construction projects undertaken for all Army and civil works projects.
The new policy for the Corps came via an Engineering and Construction Bulletin “Mandatory Consideration of Mass Timber in Army Military Construction (MILCON) and Civil Works Vertical Construction Projects. It stated that Corps personnel should consider at least one option where mass timber is a substantial structural component when comparing structural systems during early design.
"In support of Administration and Army priorities, the USACE is leaning in to further advance its long-standing efforts in high-performance and sustainable buildings with a focus on low embodied carbon construction materials," said Robert Moser, senior scientific technical manager, at the Army Corps' Engineer Research and Development Center (ERDC) in Jackson, Miss. "This includes reducing the global warming potential of construction materials such as concrete, steel and asphalt along with an emphasis on bio-based building materials like mass timber."
The Dept. of Defense in 2021 published a report on using mass timber and cross-laminated timber in military construction projects. The ERDC has been investigating mass timber and CLT's use in military construction for most of the last two decades. Under the new policy, at least one design option should be explored by Corps personnel as well as the engineers and architects contracted to work on vertical construction for the agency.
The new policy outlined in the bulletin further stipulates that if the use of mass timber increases square footage of a project beyond the Army Standard gross square footage limitation, mass timber can still considered for the project under the policy, however the increase must qualify for a waiver for the additional size and scope of the project.
The directive also says that while not all projects will be conducive to mass-timber structural support, many other structures will.
"While it is understood that there are multiple facility types within the Army and Civil Works portfolio that initially may not be conducive to mass timber systems, substantial portions of many facility types may. For example, the high bay areas of fire stations, hangars, and tactical equipment maintenance facilities may not be practical for implementation of mass timber however, the administrative portions of these facilities may," the Corps said in the policy announcement.
Moser said the ERDC has undertaken many areas of sustainable building materials work, including research and development activities, interagency coordination, partnerships with industry and academia and military construction pilot projects, as well as engineering guidance updates to codes and specifications.