OC Sanitation District HQ

The headquarters for the Orange County Sanitation District (OCSD) is a sizeable, high-profile project in Southern California. The use of mass timber, together with high sustainability and resiliency goals, provide an important, large-scale replicable model. The building is a hybrid steel and timber design, with steel lateral systems helping to ensure success of approvals while providing a ready model for replicability. High-quality materials are used on the exterior, consisting of terra-cotta cladding and shading systems, with metal cladding and a high-performance, two-way structural glazed curtain wall.

The hybrid mass timber design, a core element of the building’s sustainability narrative, takes advantage of the many benefits of engineered wood products. Modular mass timber construction with upstream design integration, in-the-field efficiency, reduced construction duration and less construction noise are all attributes OCSD has embraced. Mass timber can be a cost-effective alternative to other types of construction, including steel and concrete, and provides the promise for a financially viable reduction of small timber ladder-fuels in our forests.


As a facility located in an earthquake-prone area, the design capitalizes on mass timber’s high strength-to-weight ratio—which helps the building withstand seismic events while maintaining functionality. Mass timber also reduced the project’s carbon footprint while providing a natural warmth to the interior. The project is seeking both LEED Gold and Net Zero Energy certification.

This building consists of three 3-story buildings with a diagrid glulam roof structure at the main lobby entrance. Area A consisted of glulam beams & CLT on structural steel. Areas B & C is 3-stories of glulam columns, beams, and CLT. The material was railed from Chibougamau, BC (the last stop of the CN rail line) to storage facilities in Bakersfield & Stockton, CA. Timber erection started in July of 2022 and is scheduled to be completed in 2022.