In a recent notice by Metro Codes Mechanical Inspection Chief Alan Fort, contractors in Davidson County received updated guidelines regarding flue venting requirements for gas appliances. Detailed in the notice, which was announced today, is a series of amendments to the existing codes that necessitate the use of materials compliant with UL 1738—a standard for safety in venting gas-fired appliances.
As outlined in the amendments, all Category II and Category IV gas appliances, when vented using plastic piping, must strictly adhere to the UL 1738 standard. According to a notice published on Nashville.gov, "Where plastic piping is used to vent an appliance, the material shall be listed and labeled in accordance with UL 1738." This move to update the Mechanical Code brings clarity and enhances safety measures in the industry, directly affecting the way contractors will work on new and ongoing projects in the area.
Fort's notice comes with a stipulation of a grace period lasting 180 days for larger projects that were in the design phase before the amendments were enforced, which started on July 15, 2025. All projects commencing after January 1, 2026, are required without exception to comply. With these updates, contractors must also follow specific installation instructions provided by the vent manufacturer and use a contrasting color primer where needed.
These changes represent a significant shift in the construction and renovation of residential buildings across the county. "Plastic pipe venting materials listed and labeled in accordance with UL 1738 shall be installed in accordance with the vent manufacturer's instructions," the Metro Department of Codes and Building Safety state in their amendments. Ensuring adherence to such regulations is imperative, not only for legal compliance but also for the safety of residents living amidst the labyrinth of gas lines and vents threaded through the walls of their homes.
The new requirements have been integrated into the mechanical codes, amending sections of both the International Residential Code for One-and Two-Family Dwellings and the International Fuel Gas Code. These modifications to the existing regulations come as a response to safety concerns over the use of materials that previously may have met only plumbing standards, rather than the more stringent requirements for gas venting. Going forward, Davidson County's contractors must be more vigilant in adhering to the precise standards set forth by UL 1738 to avoid the potential risks associated with improper flue venting.
