Portland/Los Angeles-based LEVER Architecture has published a new report in collaboration with engineering firm Atelier Ten addressing what the authors call “common myths about mass timber construction.” The report, in which the firms describe and debunk four myths related to mass timber, hopes to “promote a more nuanced discussion in the industry to truly capture the potential wood has to offer.”

The first myth addressed by the report is that “mass timber buildings are carbon neutral.” The team note that while mass timber construction can be an important pathway toward carbon neutrality, other critical factors need to be considered. In particular, the team warns that many aspects of a building’s life cycle are often not captured in analyses on carbon neutrality giving an “incomplete picture of the carbon footprint.”

For design teams seeking to achieve a carbon-neutral building, the report suggests pushing for more transparency from manufacturers on the carbon footprint of interior products and mechanical equipment through initiatives such as Environmental Product Declarations (EPDs).

The report’s second myth is that “wood is always more sustainable than concrete.” The authors note that solely utilizing wood products “does not automatically make buildings more sustainable” and that it is important to take into account material sourcing and other emission sources such as transportation.

“From a pragmatic standpoint, there is a major flaw in the assumption that wood is always more sustainable than concrete and steel,” the report reads. “All wood buildings literally rely heavily on their concrete (and steel) components for foundations, cores, or as toppings on mass timber floor systems.” The report instead suggests that design teams capitalize on strategies for optimizing both wood and concrete technologies when evaluating a project’s carbon impact and take advantage of the unique properties of each material.

The third myth addressed by the report is that “mass timber buildings absorb carbon emissions.” The team instead notes that “trees sequester carbon from the atmosphere” and that “timber buildings hold carbon absorbed by trees, but timber buildings do not actively absorb carbon.”

While the report notes that mass timber is growing in popularity due to its ability to store carbon sequestered from trees before their harvesting, the authors recommend that design teams source timber that is FSC certified to ensure that forest carbon stocks are not depleted. The authors also suggest that consideration is given to the end-of-life treatment of the timber to ensure as much carbon as possible remains sequestered following a building’s dismantling or demolition.

The report’s final myth is that “all wood is good wood.” Echoing similar sentiments from the previous myth, the team notes that “wood products are only as good as the forestry practices associated with those products” and that “unless we ask how forests are being managed, we have no way of knowing if a wood product is helping or hindering progress.”

Addressing the final myth, the team also suggests that design teams use their material choices to inform what types of forests are supported and expanded and design buildings that utilize FSC-certified wood from those forests. “We should support forests that are managed for longer harvest rotations, with multi-age class stands that are proven to be more ecologically valuable, wildfire resilient, and better able to store carbon in the long term,” the team concludes.