Design-Build High-Bay Metal Roof Retrofit in Oak Ridge, Tennessee
Location: Oak Ridge, Tennessee
Industry: Research & Laboratory
Service: Infrastructure & Utility Modernization
The Situation
Oak Ridge National Laboratory needed a high-bay metal roof retrofit that would provide long-term weather protection without removing the existing roof assembly. The solution required more than new roof panels. JBrennon was responsible for designing and constructing an elevated structural system capable of supporting a new sloped roof above the existing high bay.
Under the design-build agreement, JBrennon carried the project from field investigation and structural engineering through steel fabrication, erection, roofing, drainage, and permanent fall-protection installation. The finished system also had to integrate existing ventilation and access features while protecting the sensitive research infrastructure below.
The Challenge
The new roof could not be designed from drawings alone. Its structural supports had to connect to existing steel concealed beneath the original roof at 45 individual locations. Each connection point had to be opened, measured, and coordinated with neighboring supports so the new columns, purlins, and trusses would form a level and properly aligned structure above the existing building.
Roof openings also had to be controlled carefully. The original roof remained the building’s primary weather barrier during structural installation, so every opening created for field verification or a new support connection had to be temporarily patched or permanently flashed before the end of that operation.
Material handling introduced another layer of complexity. A defined exclusion zone restricted crane swing paths, rooftop staging, and worker travel. Steel components, roof materials, equipment, and demolition debris therefore had to follow planned load paths and arrive in the sequence needed for installation.
Legacy building materials required specialized controls as well. An asbestos work plan was incorporated into the project, and sampling of the gypsum-like roof panels identified silica hazards during initial cutting. JBrennon paused the affected activity, added the required training, revised work controls, and coordinated specialty procedures before proceeding.
How We Worked
JBrennon developed progressive structural and roofing designs based on field-confirmed conditions. The engineering included connection details, support loads, roof penetrations, drainage, permanent fall protection, and the new hip-and-ridge roof geometry.
Before steel fabrication was finalized, JBrennon opened and measured 45 structural connection points across the high bay. Laser and string-line measurements were used to establish existing steel elevations and align the new supports across multiple column lines. Numbered stub columns were then matched to their field locations, connected to the existing framing with engineered steel adapters, and shimmed where necessary to establish the new roof plane.
Installation advanced systematically across the building. New steel purlins and trusses were lifted individually, aligned, braced, and connected to the completed supports. Just-in-time deliveries and controlled rooftop staging reduced congestion while allowing the erection sequence to progress within the approved lifting areas.
The completed roof assembly included:
Engineered stub columns connected to the existing structural system
New steel purlins and prefabricated roof trusses
5/8-inch plywood roof sheathing
Self-adhering underlayment providing temporary weather protection
Standing-seam metal roofing
Shop-fabricated flashing at hips, ridges, eaves, penetrations, and perimeter transitions
New perimeter gutters, downspouts, and soffit components
Permanent ridge-line davits and lifeline anchorage for future roof access
Existing rooftop features were addressed individually. Selected exhaust vents were removed to their curbs and the resulting openings were secured. Ventilators remaining in service were carried through the new roof and flashed into the finished assembly. Existing roof drains were sealed as water was redirected to the new gutter and downspout system.
The wind sock, weather station, portions of the permanent ladder, interfering pipe and conduit, and selected access framing were removed or modified where they conflicted with the new construction. The designated catwalk and its supporting steel remained in place and were integrated into the completed configuration.
Penetrations involving legacy siding were performed under the approved environmental controls, including shrouded tools and HEPA dust collection where required. Temporary flashing and weather-control measures protected the retained roof throughout structural and roofing operations.
The Outcome
JBrennon delivered a complete elevated roof system above the existing high bay, transforming a vulnerable roof condition into a durable, positively drained, and maintainable assembly.
The finished project provided Oak Ridge National Laboratory with:
A new engineered steel support structure installed at 45 field-verified connection locations
A complete standing-seam metal roof above the retained roof assembly
New flashing, gutters, downspouts, and soffits for controlled water management
Integrated treatment of existing ventilators, roof openings, and access features
Permanent fall-protection davits and lifeline anchorage for future maintenance
A weather-tight installation completed within the facility’s lifting, access, and environmental constraintsExisting interfering elements removed or modified without damage to designated structure