BOTHELL, WASHINGTON, August 7, 2023: — Cornerstone General Contractors recently broke ground on three new Seattle-area schools that will utilize mass timber building elements within the facilities – Alki Elementary School in West Seattle, Evergreen High School in White Center, and Mercer International Middle School in South Seattle.
Each project will feature a type of mass timber known as cross-laminated timber or CLT – an engineered wood product made from layers of solid-sawn lumber that has been glued together. CLT is a sustainable building product that is lightweight, yet strong and features increased fire safety performance, thermal insulation, and carbon capture when compared to steel.
To date, few K-12 schools have been constructed with mass timber as the primary structural framing system – Hilltop Heritage Elementary School in Renton is the first elementary school, and Van Asselt in North Beacon Hill is the first school for Seattle Public Schools. Both facilities, also being constructed by Cornerstone, are nearing completion and will be open for the coming school year.
“We’re thrilled to be able to build educational facilities that benefit from the inclusion of mass timber,” said Max Anderson, Cornerstone’s senior estimator who worked on each of the schools. “While building schools with wood in the Pacific Northwest during the wet seasons isn’t without its challenges, Cornerstone has been able to bring our expertise to clients so that we can mitigate some of those challenges and help clients realize the full advantages mass timber offers.”
Alki Elementary School consists of an 85,000-square-foot facility. The three-story addition will be constructed in place of the existing building, except for the gymnasium, which will remain on a small 1.4-acre site that shares space with the existing Alki Community Center. Mass timber will be utilized for the structural grid of the building. Additional sustainable features include daylight in all classrooms and high-efficiency heating and ventilation. Designed by Mahlum Architects, the school will be able to hold up to 500 students beginning in the Fall of 2025.
The new Evergreen High School will be constructed on the ballparks adjacent to the existing school building. This 231,000-square-foot facility will serve the students with new classrooms, labs, Career and Technical Education spaces, common areas, gymnasium and fitness rooms, auditorium and performing arts classrooms, library, food service production kitchen, administration, and office space. The new building, designed by Bassetti Architects, will be completed in May of 2025 with the remaining fields and site work completed in June of 2026. The project features two separate structures – one three-story, mass timber academic wing and one larger multi-purpose building.
Mercer International Middle School, also designed by Bassetti Architects, is a 176,000-square-foot, multi-story facility to house up to 1,000 students. The new school will replace the former school which was constructed back to the 1950s. Paying homage to the history of the school and the rich diversity of the surrounding community was important to consider during planning. Multiple zoning changes were required for the design of the school. With over 95% of the primary structure comprised of wood, the new facility was designed to maximize the benefits of mass timber. The building will feature CLT panels suspended by tension cables and sloped wood columns.
The interest in mass timber construction has blossomed in recent years due to owners seeking to build more sustainably with a reduced carbon footprint and using more locally sourced materials. Owners may also be drawn to mass timber for efficiencies in cost and schedule.
“Mass timber is not a one size fit all application,” said Anderson. “Cost and schedule savings are possible in vertical structures with repetitive floor plans; however, these efficiencies are more difficult to replicate in the K-12 marketplace due to the inherent characteristics of a school building and the unique programs for which they serve.”
The practice of designing spaces that include natural elements such as wood and stone to connect building occupants more closely with nature is called biophilia. Proponents of biophilic design claim it supports health, well-being and cognitive function whether utilized in office spaces, public spaces or educational facilities.
“All three of the schools just beginning construction, as well as the two we’ve nearly completed, feature the biophilic design elements of mass timber,” said Anderson. “Using exposed wood beams as well as other natural materials, maximizing natural light and using open ceilings all lend themselves to a better learning environment for students. I can’t think of a better way to contribute to our community than to build better schools and support our educators and future generations.”