A mechanical permit is required for: new HVAC system installation, equipment replacement (even like-for-like in many jurisdictions), ductwork installation or modification, gas piping, refrigerant piping, exhaust systems, commercial kitchen hoods, fireplace/stove installation, and boiler installation. Who pulls: licensed mechanical or HVAC contractor. In some jurisdictions, a general contractor can pull if supervising licensed mechanical sub. Process: (1) Submit application with equipment specifications, (2) Pay fee ($75-$500 depending on scope), (3) Install equipment per IMC/manufacturer requirements, (4) Rough mechanical inspection — ductwork, gas piping, refrigerant piping before concealment, (5) Final mechanical inspection — equipment operation, clearances, combustion air, venting. Common inspection items: equipment clearances to combustibles, combustion air openings, gas shutoff accessibility, condensate drainage, refrigerant line insulation, duct sealing (required in many energy codes), exhaust termination distances from openings.