Ryan Field | Northwestern University

Illinois

Date: 2026

Overview of Ryan Field's seating bowl under construction, with red flags marking expansion joint locations along the upper concourse edge.

Watertight Stadium Expansion Joints in the Seating Bowl

Project Background

Northwestern’s new Ryan Field replaces the 1926 stadium that stood on the same site for nearly a century. Like any large stadium, it incorporates expansion joints throughout the structure to accommodate movement from thermal change, structural loading, and seismic forces. In the seating bowl, those joints maintain a watertight seal through sixteen tread-and-riser transitions in the northwest lower bowl alone, tracing the seating profile through repeated elevation changes without a break.

Project Details

Location	1501 Central Street, Evanston, IL
Owner	Northwestern University
Architect	HNTB (architect of record), Perkins&Will (associate design architect)
General Contractor	Turner-Walsh Joint Venture
Installer	IWS, Aurora, IL
Capacity	35,000
Completion	2026
Products	Seismic Colorseal, Seismic Colorseal-DS, Emshield DFR2, SJS, SJS-FR2, DSM System, RoofJoint

Engineering drawing showing the northwest lower bowl joint schedule for Ryan Field, with row-by-row product and dimension table, manufacturing side view details, and installation guide side view illustrating the tread-and-riser transitions from tub to parapet.

Elevation and Plane

Expansion joints in a stadium rarely stay level. In the seating bowl, the joint follows a linear path down the aisle in plan, but its elevation changes continuously through the seating profile. Tracing that path from tread to riser and riser to tread, the joint moves between horizontal and vertical planes along the same straight line, part of a single run that never breaks.

In the northwest lower bowl, that line includes sixteen distinct tread-to-riser transitions, a 90-degree shift from horizontal to vertical plane, and a bump notch termination between the parapet and the tub. The joint width shifts row to row, from 9 inches (229 mm) at the base to over 11 inches (279 mm) near the top, sized to the movement expected at each location while the seal remains unbroken across the run.

Elevated view of Ryan Field's seating bowl showing the expansion joint running down the aisle through multiple seating tiers.

Expansion joint running from the playing field wall through the seating bowl steps at Ryan Field, showing the joint's continuous path across the transition from field level to the tread-and-riser stairway.

Continuity matters because the demands on the joint don’t stop at a transition. Movement continues through it. So does waterproofing. Where fire ratings apply, so does fire protection. Every transition is a potential point of failure if the seal breaks.

A Custom Fit at Every Transition

At each tread-riser transition, the coverplate is custom-configured to match the chamfer where tread meets riser, extending up the riser face rather than stopping at the tread, with an integrated upturn detail that carries the seal over the chamfer edge. Because chamfer geometry varies by location, each plate is manufactured to field-verified measurements rather than a standard shop dimension.

Close-up of a custom coverplate at a tread-riser transition at Ryan Field, showing the upturn detail carrying the seal over the chamfer where the riser meets the tread.

Engineering drawing showing plan and side views of custom coverplates for Ryan Field, with upturn detail, bevel detail, and countersink dimensions for field-verified manufacturing.

Factory-Fabricated Transitions

To accommodate the seating bowl’s plan-linear, elevation-complex geometry, transition assemblies are manufactured off-site as field-verified preformed joint sections, providing a continuous, watertight seal through changes in elevation and joint intersections. Built to match as-built field conditions and ready to install, the transitions replace time-consuming field fabrication with a faster, more reliable installation process.

Close-up of the expansion joint installed through a tread-riser vertical transition at Ryan Field, showing the continuous seal as it steps from tread to riser to tread.

Close-up of the 90-degree vertical transition in the Ryan Field expansion joint, showing the factory-fabricated coverplate carrying the seal through the direction change without a break.

Expansion joint terminating at the parapet wall at Ryan Field, showing the seal carried from the concrete deck up through the wall condition.

Seven Systems, One Continuous Seal

Seismic Colorseal, Seismic Colorseal-DS, Emshield DFR2, SJS, SJS-FR2, DSM System, and RoofJoint were specified across Ryan Field, each selected for the joint width, expected movement, and fire-rating requirements of a specific location. A stadium of this scale presents a wide range of those conditions, so no single system could address all of them.

Each product is matched to the joint it serves. Together, they form a set of watertight stadium expansion joints that carry an unbroken seal from one building condition to the next, tied together by the same factory-fabricated transitions that run through the seating bowl.

Expansion joint running along the perimeter wall bordering the playing field at Ryan Field, marked with red safety flagging during construction.

An Ongoing Body of Work at Northwestern

The project adds to Sika Emseal’s history at Northwestern University, which spans multiple buildings over the past several years, now including the seating bowl of a 35,000-capacity stadium.

Conclusion

Beyond accommodating movement, Ryan Field shows what continuous expansion joint performance looks like at scale: systems selected for site-specific conditions, transitions engineered rather than built in the field, and a seal that carries through every plane change without a break.