By Ray Reedy, AIA, LEED AP BD+C, PYATOK Associate

We at PYATOK have embarked on an enlightening journey designing the Village SF Wellness Center, a six-story mass timber project serving San Francisco's urban Native American community and celebrating Indigenous values in the heart of Mission District. This venture into the realm of mass timber has been a stimulating challenge throughout project design, and we are eager to share insights gained along the way.

There are immense potential benefits to building with mass timber, and we are optimistic that more familiarity and broader adoption of the system will buttress our collective progress towards a more sustainable, and more delightful, built environment.

Empower Team Commitment

Particularly for owners new to mass timber, which is nearly all of our clients, the ins and outs of this construction method can be intimidating and overwhelming; sustaining awareness of the system as an exciting opportunity can help turn owners from skeptics into committed allies. This requires up-front work on the part of the design team to demonstrate the tangible and intangible benefits of mass timber (such as connection to nature and expression of values), and it requires developing a road map  clarifying how the entire team will work together to implement this innovative system. Early investment in education and planning will help preserve the mass timber system as a key component to a project's identity and character, avoid the VE chopping block, and instill collective motivation and determination to succeed.

Leverage Inherent Qualities

When we design the mass timber as essential to a project’s identity and users' experience of the space, we take full advantage of the system’s strengths. It is a material that warms spaces, connects people, and changes our relationship to the built environment. We amplify this charisma when we express the structure, tailor the project's design to it, and develop the interior vision around it. By expressing and exposing the structure to the greatest feasible degree, we are able to establish themes, architectural tectonics, and stories in a way no other structural system can.

Start With Rules of Thumb

Mass timber columns, beams, and panels are not yet standardized products like dimensional lumber or metal studs; mass timber manufacturers all do things slightly differently from one another. Still, rules of thumb can be used in early concept and feasibility. These include generalizations of column spacing with post-and-plate vs post-and-beam structures, typical panel widths, and typical beam spans. For example, a 5-ply CLT panel is likely able to span 16 feet from beam to beam, but a 20-foot span will likely require a 7-ply panel. WoodWorks, a wood construction advocacy group, publishes a Mass Timber Design Manual filled with resources, including rules of thumb like this that can be useful from early in the design process. This manual and other industry publications can be used as educational resources for ourselves and our teams on early-stage rules and standards.

Engage Trusted Industry Experts

As helpful as industry resources and rules of thumb are, mass timber design teams will need expert guidance to refine the design and transition from concept/feasibility to a technically sound building. Finding partners with mass timber experience to bring in early, and taking the time to build trust as a team, will pay dividends later. Whether it's a structural engineer to test alternatives, a general contractor and mass timber supplier to do initial pricing work, or a construction manager to help advise on timeline and financing, early team building allows for early decision-making in a way that maximizes the benefits of mass timber to the owner and residents, providing reassurance and confidence in the decision making process.

Ensure a Site's Margin of Flexibility

Sites best suited for mass timber are those with at least a little flexibility in size and shape to allow for the grid regularity that gives mass timber the most efficiency. Every twist and turn required to accommodate a unique site condition — such as irregular topography or existing improvements — adds proportionately greater waste and cost compared with cast-in-place concrete or light-framed structural alternatives. Similarly, sites with space for cranes and lay-down greatly simplify erection logistics. Mass timber can be the right call for highly constrained urban sites (like the 0.15-acre, midblock Village SF Wellness Center) as long as that margin of flexibility is in place.

Keep MEP Systems Practical

Because mass timber is fully prefabricated, on-site modifications can be challenging and expensive. All building systems, including MEP systems, need to be modeled to a high level of detail in order for the mass timber shop drawings to be thoroughly coordinated. To facilitate this coordination and avoid costly field modifications, MEP systems need to be practical and flexible. Long duct runs, plumbing drops over occupied rooms, and water lines running to far-off corners result in more applied finishes and less exposed timber. We can preserve desired ceiling heights and exposed timber by simplifying and regularizing the architectural layout and designing the MEP systems to work with the structure, for instance by running electrical conduit in the topping slabs and running ducts parallel to beams. 

Applicability to Housing

In addition to our work on the Village SF Wellness Center, we have been exploring mass timber for multifamily applications. Two of the system's primary benefits are its lighter weight (and therefore reduced foundation size) and rapid erection. When realized, these benefits are tangible for any multifamily typology. Market-rate housing in particular can realize direct financial benefits from reductions in construction schedule. Campus housing may be even more suitable since project delivery is strictly tied to the school year calendar, the sites are often large, and the units are generally regular and repetitive. Regardless of housing type, residential projects with smaller typical room sizes generally relate well to the column spacing of mass timber structures. 

To Be Continued

In our next installment, we will discuss more about how mass timber can help us deliver sustainable, delightful, and cost-effective affordable housing. Meanwhile, we look forward to breaking ground on the Village SF Wellness Center and advancing our other mass timber projects, including Kashia Tribal Housing in Windsor, CA, and Timber45 in Seattle's U District.

Links

• The Village SF Wellness Center — https://www.pyatok.com/work/project/156/THE-VILLAGE-SF-WELLNESS-CENTER
• Friendship House — https://www.thevillagesf.org/ 
• Softwood Lumber Board Mass Timber Competition — https://softwoodlumberboard.org/mass-timber-competition-building-to-net-zero/ 
• WoodWorks Mass Timber Design Manual — https://www.woodworks.org/resources/mass-timber-design-manual/ 
• Kashia Tribal Housing — https://www.pyatok.com/work/project/163/KASHIA-TRIBAL-HOUSING 
• Yurok Wellness Center — https://www.pyatok.com/work/project/188/YUROK-WELLNESS-CENTER

About PYATOK

PYATOK architecture + urban design is a mission-driven, full-service architectural firm based in Oakland, California. We specialize in the master planning and design of multifamily residential communities and community services, including affordable housing of all types as well as market-rate and student housing, mixed-use transit-oriented developments, and community resource centers. Our staff work together under the belief that the best urban developments come about through strong partnership between project sponsors, residents, city staff, and an open-minded design team.