When Does a Commercial Kitchen Need a Hood?

Almost every restaurant, café, commissary and church kitchen reaches the hood question at some point: when a new fryer arrives, when a lease is on the table, or when an inspector writes something up. The short version is that the cooking decides the hood, and the local authorities decide the details. This guide explains the difference between the common hood types, why a hood never works alone, and where commercial kitchen ventilation service fits alongside the other trades in your kitchen.

Which cooking equipment needs a grease hood?

Cooking equipment that produces grease-laden vapor generally needs a grease hood with a fire-suppression system over it. That usually means fryers, griddles, flat-tops, open burner ranges, woks, tilting skillets and charbroilers. The vapor these appliances throw off condenses as grease on every cool surface it reaches, and grease in a duct is fuel.

A grease hood is often called a Type I hood. It has baffle filters that knock grease out of the airstream, a welded grease duct that runs to a roof-mounted exhaust fan, and a fire-suppression system that discharges over the cooking surfaces and into the hood and duct if a fire starts. The exact requirements for a particular kitchen are set locally, not by a restaurant supply catalog.

What equipment may need only a heat or condensate hood?

Equipment that produces heat, steam or odor but not grease may need a lighter heat or condensate hood, often called a Type II hood, or in some cases no hood at all. Common examples include some ovens, steamers and commercial dishwashers. A Type II hood exists to carry heat and moisture out of the room so it does not condense on the ceiling or cook the staff.

How cooking equipment commonly lines up with hood types (the local code official makes the final call)

Equipment	What it produces	Commonly placed under
Fryers, griddles, flat-tops	Grease-laden vapor	A grease hood with fire suppression (Type I)
Charbroilers and open ranges	Heavy grease vapor and smoke	A grease hood with fire suppression (Type I)
Commercial dishwashers	Heat and steam	A condensate or heat hood (Type II), or none
Some ovens and steamers	Heat and moisture	A heat hood (Type II), or none
Countertop warmers and some small appliances	Mild heat	Sometimes no hood, depending on the review

Why is a hood never just a hood?

A kitchen hood is one piece of a system that also includes the exhaust fan, the grease duct, the fire-suppression system and the make-up air that replaces what the fan removes. Change one piece and the others are affected. A strong fan with no replacement air simply sucks the building negative and stops pulling; a well-sized hood with a worn fan belt lets smoke roll out at the cookline.

• The hood has to be large enough and positioned correctly to capture the plume from the equipment beneath it.
• The exhaust fan has to move the airflow the hood was designed for, through the full length of the duct.
• The grease duct has to be sealed, sloped and accessible for cleaning.
• Fire suppression has to cover the appliances actually under the hood today, not the ones there when it was installed.
• Make-up air has to replace the exhausted air, heated in a Twin Ports winter, or the whole system underperforms.

Our guide to what a make-up air unit does explains that last piece, and the resource on restaurant negative pressure and make-up air shows why a cold, drafty dining room is often a hood-balance problem rather than a heating one.

How often does a kitchen hood need cleaning?

Kitchen hood and grease duct cleaning frequency depends on the type and volume of cooking, and it is set by the fire code and the certified hood-cleaning contractor who inspects the system. A high-volume fry or solid-fuel operation needs cleaning far more often than a church kitchen that cooks a few times a month.

Grease duct cleaning is performed by certified hood-cleaning contractors, and fire-suppression systems are serviced by licensed fire-protection contractors. We work alongside both; we do not replace them. Our part is the mechanical system: hood and duct integrity, exhaust fans, belts, bearings and motors, controls and interlocks, make-up air, and the balance between them. If we find grease buildup or a suppression concern during service, we document it and tell you.

What are the signs a kitchen hood is not doing its job?

The clearest sign a kitchen hood is not doing its job is smoke or steam escaping from under the hood at the cookline instead of being captured. Other signs usually travel with it:

• Grease film on the ceiling, walls or lights near the hood.
• Cooking odors reaching the dining room or a neighboring tenant.
• An exhaust fan on the roof that is noisy, vibrating, slowing or dripping grease.
• Entry doors that are hard to open while the hood runs, which points to missing make-up air.
• A cookline that changed, such as a charbroiler added under a hood designed for lighter duty.
• A fire or health inspection finding about ventilation.

Each of these has different fixes, so the right first step is measurement of hood airflow, fan performance and kitchen pressure rather than a guess. Some owners are surprised to learn the answer is a bigger hood, not a bigger fan.

What should you do before signing a lease or buying equipment?

Before signing a lease or buying cooking equipment, have the existing kitchen ventilation assessed against the menu you actually plan to cook. A space that ran as a bakery or a coffee shop may have a heat hood, or nothing, where your concept needs a full grease hood with suppression, a new duct through the roof and make-up air.

That matters in a strip center in Thomson, a converted storefront in Wrenshall or a community hall kitchen in Maple alike. Ask who owns and maintains the hood, fan and rooftop equipment under the lease, and ask the building department and fire marshal what the new use will require. Our post on who handles HVAC under a commercial lease covers the lease side.

What can kitchen staff do, and when should you call?

Kitchen staff can keep the baffle filters clean on the schedule your cleaning contractor recommends, make sure the hood is switched on before cooking starts, keep the rooftop make-up air intake clear of snow, and note when smoke escapes or doors get hard to open. Those notes shorten any service visit.

Fan motors, belts, interlocks, airflow measurement, hood sizing and make-up air belong with a commercial technician, and grease duct cleaning belongs with a certified hood cleaner. If you are opening, expanding or changing a menu, or if your hood is losing the fight with the cookline, ask for an assessment of your kitchen hood and exhaust system.