Nashville-Davidson, TN HVAC permit requirements

2024 IRC with Metro amendments, BL2025-898 (Metro Code 16.08.010.C / 16.08.014; mechanical amendments at 16.16.230). Final passage July 15, 2025; signed July 16, 2025. Chapter 11 amendments: the 2024 insulation/U-factor tables are replaced with the 2009 IRC tables; N1102.5.1.2 air leakage testing is replaced with the 2009 testing/visual inspection option; N1103.5.2 is rewritten.

2024 IECC as amended (Metro Code 16.08.016): 'The 2024 Edition of the International Energy Conservation Code is hereby amended so that it meets and does not exceed the 2018 International Energy Conservation Code standards as adopted by the State of Tennessee, per Tenn. Comp. R. & Regs. 0780-02-23-.02(1)(b).' Residential work also falls under the amended 2024 IRC Chapter 11.

2024 IRC M1401.3 is kept. The BL2025-898 mechanical amendments to the IRC (16.16.230) add M1203, M1601.1.1(9), M1601.3(1), M1901.3, amend the M1601.4.1 exception, and amend fuel-gas sections. They do not amend M1401.3, which requires sizing per ACCA Manual S based on loads per ACCA Manual J 'or other approved' methodologies.

2024 IRC M1601.1 is not amended (Manual D, the manufacturer's instructions, or other approved methods). Metro adds M1601.1.1(9): 'All ductwork installed in non-conditioned and not completely conditioned areas such as, but not limited to, crawl, attic and floor/ceiling assemblies shall be insulated.' It also bans spray polyurethane foam on exterior ducts (M1601.3(1)).

Metro's permit-required list for 1- and 2-family dwellings: 'AIR CONDITIONING-NEW & REPLACEMENT UNIT' = YES-G/M (gas/mechanical permit); 'FURNACE CONDENSER REPLACEMENT' = YES-G/M; 'FURNACE-REPLACE WITH DIFFERENT SIZE OR FUEL' = YES-G/M; 'HEATING SYSTEM-CHANGING SIZE OR CHANGE OF FUEL' = YES-G/M; 'FURNACE OR CONDENSER REPAIR' = NO. The list does not say whether a load calculation is required for a replacement.

Not verified for residential. Metro's residential permit page mentions field inspections for 'Model Energy Code' compliance. Metro's Drawing Requirements (Feb 2025, written under the 2018 codes and mainly commercial) says 'Energy compliance certificates shall be provided in the set as per 2018 IECC and www.energycodes.gov'.

Trade permits (plumbing, electrical, mechanical) are applied for or self-issued in ePermits by registered licensed contractors. Credentials are obtained by emailing Metro Codes. Residential building permits need a site plan and floor plans; 'Construction plans are required for residences exceeding 5,000 square feet'. No Metro checklist found that asks for Manual J/S/D or heat loss/gain with a gas/mechanical permit.

None found. At adoption Metro announced a 180-day grace period for projects with preliminary designs completed under the 2018 codes (news release; adopted July 2025, so the window has presumably passed).

epermits.nashville.gov