The US Army Corps of Engineers has now mandated a policy that requires a “mass timber structural option be considered at the design phase in all of its vertical construction projects going forward.”
It is part of a push by the US Department of Defence to decarbonise, with the US Army’s primary engineer formation focused on the engineer regiment, military construction, and civil works.
This means that the US Army will become the first military organisation in the world to embrace mass timber in both on-site installations and civilian housing projects.
It comes after Wood Central reported last month that a new US Department of Defence Resilient Building Policy will, for the first time, decide if and when sustainable materials and technology can used in military installations.
Published last month, it requires “all US Army MILCON and Civil Works vertical construction projects to consider at least one option where mass timber is a substantial structural component when comparing structural systems during early design.”
The new policy applies to all new projects starting from 2027, including “cross-laminated timber (CLT), glue-laminated timber (Glulam or GLT), dowel-laminated timber (DLT), nail-laminated timber (NLT), and laminated veneer lumber (LVL).”
It represents a significant milestone for low-carbon construction materials, with the market for MILCON (the US Military Construction Program) enormous.
In September, US Congress approved more than US $16.674 billion in MILCON spending – split between military construction ($14.73b) and family housing ($1.94b), with more than US $1.47B in spending allocated for the US Army Corps of Engineers.
Wood Central understands the US Army is already using low-carbon concrete and mass timber to develop three new projects, including two bases at Joint Base Lewis McChord in Washington and a total retrofit of the Fort Liberty barracks.
However, the policy acknowledges that mass timber will not be considered in low-rise military installations, for example, less than three levels, with cost and supply amongst key considerations.
“Initial costs will likely be the determining factor, and in certain CONUS (a US Department of Defence term to identify the states of USA) regions, mass timber may not be widely competitive at this time.”
It comes as the US Army Corps of Engineers R&D Centre, known as the ERDC, spent almost 20 years researching the use of mass timber and CLT in military construction.
In 2021, it assisted the US Department of Defence in publishing a groundbreaking report on using mass timber products in military construction projects.
The report highlighted its potential uses for on-base and Forward Operating Base/Contingency Operating Base Facilities operations and supported blast tests in 2016 and 2017 to test durability under heavy fire.
It found that CLT’s “sweet spot” is mid to high-rise buildings, “where it competes with heavier steel and concrete”. Still, it acknowledged that light-gauge metal stud construction is advantageous in low-rise military bases “due to its load capacity limitations.”
According to Robert Moser, Senior Scientific Technical Manager for the ERDC, “the US Army Corps of Engineers 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.”
“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 emphasis on bio-based materials supports a push by the UN to substitute carbon-intensive building materials, like steel and concrete, for bio-based materials like timber, bamboo, and biomass, which will save emissions by up to 40% by 2050.
As part of a major report published by the UN Environment Programme and the Yale Centre for Ecosystems and Architecture, it found that “processing concrete, steel, and aluminium are together responsible for 23% of the overall global emissions.”
The pivot to climate comes as the Biden Administration introduces new legislation mandating that ‘accounting for ecosystem services’ be considered in all US Government cost-benefit decisions.
In August, the US Government released the first-ever guidance on accounting for ecosystem services in benefit-cost analysis.
This guidance will advance and strengthen analyses of regulations and government investments – including US Army spending.