SEATTLE (April 9, 2023) – Building a hybrid mass timber high-rise is now nearly as cost-effective as building a comparable concrete tower. This could be great news for both the environment and renters in the Seattle area.

A new study co-authored by PCL Construction, DCI Engineers, and Weber Thompson examines the decreasing costs of mass timber construction and its potential to expand residential space in densely populated urban regions.

Intermediate high-rise towers (those 180 feet or shorter) are often under-built in urban areas due to an unfortunate intersection of construction cost and code requirements. Even if the zoning allows, many developers forgo developing high-rise residential projects that are under 200 feet due to the cost of concrete construction at this scale. Mass timber construction provides an alternative that can be cost-competitive or more economical under the right circumstances – paving the way for the construction of more buildings in the intermediate tower height zone, and potentially increasing housing density.

Mass timber is a renewable construction material created using fast-growing lumber, often through a process of laminating planks together to create the buildings blocks of a tower. Pieces are pre-manufactured in a separate facility and then placed by crane on the construction job site, reducing the project schedule and resulting in a more efficient use of materials.

The study found that when factoring in cost-savings from the reduced schedules associated with using prefabricated mass timber, combined with an improved material supply chain, an 18-story residential highrise built using a hybrid of mass timber and concrete could cost as low as $74.45 per square foot to build. While slightly more expensive than the cost of $71.09 per square foot of a concrete building of the same size, it’s a competitive price that may influence developers to think twice about the materials used in their next project, especially to differentiate their product in a competitive leasing market. This shift is particularly relevant as the push for low-carbon construction is increasingly legislated via new carbon taxes and mandates.

Key findings of the study:

Embodied carbon reduction:
An 18-story hybrid building built of concrete and mass timber could store up to 3,350 metric tons of CO2e throughout the building’s useful life; the equivalent to the carbon sequestered by 4,000 acres of U.S. forests in one year or eliminating 745 gasoline-powered passenger vehicles from the road for one year.

Biophilic benefits:
An intriguing study recently released by Harvard reinforces the positive impacts of biophilia – people’s desire to connect with nature – on human health. Mass timber buildings with exposed wood create interior environments filled with biophilic connections. The allure of these health benefits along with the natural beauty of wood will differentiate projects in competitive leasing markets and potentially attract longer-term leases.

Impact on increased density and affordability: In urban infill zones with floor area or height restrictions, high-rise residential towers under 200 feet have traditionally been economically challenged in purely concrete construction. Mass timber construction could open up more sites with higher density for development if time and cost savings can be realized, creating an opportunity to address housing needs in the region.

The full report, “Hybrid Tall Timber: Mass Timber Residential High-Rise Study,” was co-authored by PCL Construction, DCI Engineers, and Weber Thompson. A copy of the report can be downloaded here.

About PCL Construction
PCL is a group of independent construction companies that operates throughout the United States, Canada, the Caribbean, and Australia. As one of the largest contracting organizations in North America, PCL completes more than $7 billion USD in work annually, building projects that shape communities. The company’s 100% employee ownership model fuels a culture of commitment for clients in the buildings, civil infrastructure, heavy industrial and solar markets. With a strategic presence in more than 30 major centers, PCL’s leadership teams consistently drive innovation and set new benchmarks for excellence, bringing unparalleled skill to every project. Watch us build at PCL.com.

About DCI Engineers
DCI Engineers is a nationally recognized civil and structural engineering firm with expertise in high-rise, multi-family, higher education, K-12, affordable housing, life science, office, industrial, bridge, right-of-way, and sustainability services. Founded in 1988, DCI Engineers employs more than 350 staff in Washington, Oregon, Idaho, California, Texas, Alaska, Colorado, Montana, Delaware, Pennsylvania, and New York. For more information, visit dci-engineers.com.

About WEBER THOMPSON
WEBER THOMPSON is an award-winning, majority women-owned architecture, interior design, and landscape architecture firm. Our extensive experience with high-performance mass timber construction and high-rise housing gives us valuable insight into how to successfully deliver a tall mass timber tower. With mass timber, the details matter. Weber Thompson has a reputation for collaborating with consultants, contractors, and fabricators to deliver high-quality mass timber projects. Understanding timber species, sourcing, and manufacturers allows us to design for a competitive marketplace while creating a beautiful and performative project. For more information go to www.weberthompson.com.