The Downers Grove North campus is home to the original Downers Grove High School, which was constructed in 1928 to serve the growing population of what was at the time a small, railroad-centered town. Originally designed to serve 350 students, the building has undergone multiple additions over the decades to accommodate a continuously growing population.

In May 2019, after a successful referendum, the District 99 Board of Education broke ground on a significant renovation and addition to what is now known as North High. The team at Wight & Company knew that integrating the original school with the subsequent structures would present interesting design, engineering, and construction challenges.

Enter the Learning Commons, a flexible educational space where students and staff can socialize and work collaboratively, with spaces for individual and small group study. The Commons is centrally located, with key student services surrounding the covered courtyard. The biggest challenge? Covering this large area with a roof that would allow for maximum light and minimum disruption to the original 1928 structure.

Time-lapse video of the truss installation

Understanding the need to create a human-centric gathering space, Wight’s structural engineers challenged themselves to develop a roof system that provided a unique framing aesthetic, met the budget, and was easily constructible. The process involved developing several prototypes and testing each scheme to identify which one best met the design criteria. Once selected, the solution was refined to introduce simplification, efficiency, and repetitiveness while maintaining the aesthetic vision.

The selected structural scheme utilizes a series of eight custom king post trusses to span the width of the courtyard. The top chord of the trusses is composed of curved steel pipe sections that form the shape of an “X.” Steel rods from the ends of the truss span to the “king” post at truss mid-span. The configuration creates a clean and light appearance while providing an efficient structural solution.

The eight trusses are supported by a perimeter steel frame - elevating them above the roof line and creating a “floating” feeling to the structure. The perimeter steel is in turn anchored to and supported off the original school buildings. The perimeter frame successfully forms both a support structure for the trusses and a transition element to the buildings below.

Several methods were incorporated to simplify the fabrication and erection processes. Specifically, all eight trusses are exact duplicates of each other. This achieved efficiency and quality in the shop fabrication processes through repetitive detailing, assembly, and inspections of complex elements and connections. Additionally, the trusses were sized to fit on a single truck such that they could be safely and efficiently transported to the construction site. Once on site, the trusses were quickly lifted and locked in place on the perimeter steel frame.

The resulting roof structure literally spans the decades of school buildings at North High, resulting in a Learning Commons where what was previously an unused courtyard is now unified in a single light-filled space.

About the Author - Matthew Aquino, PE, SE

Overseeing Wight’s engineering groups, Matthew leads the teams through small to large-scale, complex projects. He fully leverages the company’s resources to provide efficient, economical, and constructible engineering systems while driving project aesthetics, quality, energy efficiency, and value.

Matthew is an experienced building engineer with an emphasis on project design, analysis, coordination, and delivery methods. His work spans all market sectors and includes the implementation of specialty projects and spaces such as exposed structures, net-zero energy, and storm shelters.

Contact Matthew via email for more information.