Gwinnett County Historic Courthouse
The existing built-up roof system including roof insulation, bituminous flashings, scuppers, downspouts, gravel-stop fascia, and other metal flashings were being removed down to the wood plank deck. The roof extended beneath a built-in gutter for the upper, steep slope slate tile roof. Therefore, this area was closed in with plywood to create better base flashing detail. A static roof vent on a lower roof area was in close proximity to an upper roof built-in gutter. This static vent was planned to be removed, the decking repaired, and three smaller static vents were planned to be installed to vent the attic space. Lead flashings, vent stack bases, and pipe flashing were also being removed. A new cold-process modified bitumen roof system with bituminous flashings, gutter, downspout, and metal flashings was planned for installation. The copper scupper, conductor head, downspout, and coping were to be replaced with new copper drainage facilities and flashings. At any areas that were not visible, such as counter flashing locations, galvanized steel was to be used. The skylight was designed to be replaced with a new impact resistant skylight.
Historic courthouse with a wood deck presented several issues in determining the appropriate roof system to install (Gwinnett County is partial to modified bitumen roofing), what metal to use for flashing, and how to access the building. This building is frequently used for tourism, meetings, and formal events. Also, the client is insured by Factory Mutual and therefore the roof system had to be designed to meet the requirements of the insurance company. Insulation was added over the existing decking which will likely reduce the heating/cooling cost of the facility