500 County Center (San Mateo County Office Building)

When the County of San Mateo needed a new headquarters for their 600 employees, they challenged architects at Skidmore, Owings & Merrill (SOM) to design a building that was sustainable, iconic in style, and built to budget. When it was completed, 500 County Center became the nation’s first net-zero energy civic building constructed using mass timber. The project demonstrates wood’s suitability and economic viability for large-scale public projects.

Wood is left prominently exposed throughout the five-story structure, designed using glulam beams and columns and 5-ply CLT panels. Double glulam beams flank each column throughout the building; the configuration shortened the required CLT span, helped optimize mechanical system layout, and provided better floor vibration performance. The shallower beams also allow more natural light into the building.

Design and installation optimization added considerable value. SOM achieved material optimization through efficient bay sizing, a repetitive structural system, and resourceful CLT panel specifications. Timber’s light weight allowed the use of mobile cranes, reducing costs and allowing fast, efficient installation. The value afforded by speed of construction was significant, saving about three months in the schedule. Exposed timber also reduced the need for other interior finish materials and provided the County with the iconic design they wanted. Officials have credited the beautiful building with helping them bring employees back to the office.

The project is on track to achieve LEED Platinum certification.

Read and download the WoodWorks Technical Case Study