Recent Project Milestone: April 2026 – Topping out occurred, applying the final CLT panel to the delta beam roof. With the last piece of mass timber set, the structural “bones” of the building are now fully in place. Stay tuned for more exciting updates as this facility comes to life!
Anthem Structural Engineers serves as the Engineer of Record for the City of Boulder Western City Campus.
The new Civic Center at the City of Boulder Western City Campus Pavilion Building poses a unique challenge: integrating a new 118,203-square-foot mass timber expansion onto an existing three-story concrete hospital. As a Type IIIA building, the project requires a 1-hour fire resistance rating for its primary structural frame, floors, and roof, requiring meticulous detailing for all connections.
Anthem is solving significant architectural and engineering challenges to execute this complex hybrid structure. A key innovation is the design of a new top story with slim roof profile to meet building height limits. We are achieving this by flush-framing 5-PLY CLT (Cross-Laminated Timber) roof panels directly into Peikko Deltabeams, a composite steel and concrete beam solution. This elegant design creates a flat ceiling plane, 1-hour rated beams without spray or architectural detailing, eliminates the need for dropped glu-lam beams, and maximizes head height.
Our team is delivering robust and efficient solutions for other core building elements. The remaining four levels consist of a classic glu-lam post-and-beam system with 5-PLY CLT floors. The connection of these new floors to the existing concrete building requires the use of multi-ply glu-lam beams to manage loading and architectural head height.
The ground floor features a signature two-story, multi-purpose space that showcases our long-span capabilities. This area is framed by 5-foot-deep glu-lam beams spanning over 60 feet to support the third-floor office space, a fourth-floor outdoor terrace, and the roof structure above.
The project also highlights Anthem’s ability to manage intricate site conditions and sustainable practices. The three main stair cores are composed of a hybrid system of concrete perimeter walls and mass timber stairs, utilizing 3-PLY CLT panels as stringers with glu-lam beams and precast concrete treads. One stair core uses a full-building-height central 3-PLY CLT wall to attach the treads, while the others use deep CLT panel stringers. Our team is integrating salvaged steel members from the original hospital’s demolition, refabricating them for reuse as new columns and beams.
The existing concrete building requires extensive strengthening to accommodate additional loads and updated code requirements. This is accomplished through a combination of FRP (Fiber Reinforced Polymer) wrap on selective beams, slabs, and columns, as well as new concrete beam and column sections poured under the existing slabs. This, along with a carefully planned partial demolition, is crucial in creating a seamless and constructible interface between the new mass timber structure and the existing concrete building.
