Kitchen Exhaust Ductwork: The Details That Decide Whether a Job Passes

This piece isn't about home energy upgrades like insulation or heat pumps — it's trade advice for people who install commercial kitchen exhaust systems, the ductwork that vents smoke and grease from restaurant-style cooklines. A veteran sheet metal and ventilation installer explains that these systems rarely fail inspection because of the fan itself. They fail because of smaller details: whether the hood actually captures smoke and grease, whether duct joints are sealed tight enough to stop grease leaking into ceiling spaces, whether access doors exist where someone can actually reach them to clean the duct, whether the duct is sloped properly so grease drains back rather than pooling, and whether fire-rated sealing is installed anywhere the duct passes through a wall or floor meant to stop fire from spreading.

The article lists common shortcuts that cause problems: taping joints instead of properly sealing them, screwing through duct walls, using flexible duct on a grease line, running a kitchen with grease filters removed, or boxing in ductwork before testing it with a light to check for leaks. These systems follow safety codes such as NFPA 96 in the U.S. and equivalent standards elsewhere.

For a homeowner, this isn't directly relevant unless you own or renovate a space with a commercial-style kitchen hood, such as a restaurant, home with a commercial range, or accessory unit with professional kitchen equipment. It doesn't touch typical residential range hoods, insulation, heating, or rebate programs.