Do I need a permit for HVAC work in
Greenville, Texas?

Greenville, Texas HVAC permits—the key details

The threshold for when you need a permit boils down to one rule: if you're changing, adding, or replacing any HVAC equipment in a conditioned space or connected to ductwork, it needs a mechanical permit unless you're an owner-occupant doing a like-for-like replacement yourself. Texas Property Code § 1-2-3 allows owner-builders to work on their own primary residence without a contractor license, but Greenville's Building Department still enforces permit intake for code compliance. A straight swap—your old 3-ton Lennox for a new 3-ton Lennox in the exact same location, same ductwork, same thermostat wiring—may qualify for the residential owner-builder exemption, meaning no permit filing required. However, the moment you modify ductwork, upgrade to a larger capacity, add a second zone, relocate the outdoor unit, or install a new system in a previously unconditioned space (like converting an attic to a bedroom), a permit is mandatory. If you hire a contractor, a permit is always required, period. The contractor is legally responsible for pulling it; if they claim they don't need one, that's a red flag that they're not properly licensed or insured. Greenville's Building Department processes mechanical permits using the International Mechanical Code (IMC) 2015 or the most recent adopted edition—verify which year with the department—and reviews applications for compliance with ductwork sizing (per Manual J load calculations), refrigerant charge verification, electrical interlock safety, and clearance from combustibles for gas furnaces.