Commercial hoods are the most misunderstood piece of a new kitchen. The rules turn on one distinction: whether your cooking makes grease-laden vapor or just heat and moisture. Below are plain answers to the questions operators ask most, covering hood types, sizing, dimensions, cost, and installation. These are general principles under the International Mechanical Code and NFPA 96, not a design; a mechanical engineer and your local authority (AHJ) size and approve the real system.
If you operate cooking equipment that produces grease-laden vapor, smoke, heat, or steam, you almost always need a hood. Fryers, griddles, charbroilers, and ranges require a grease (Type I) hood; dishwashers and some ovens need a heat/steam (Type II) hood. A few low-heat setups escape the requirement. Use our do I need a hood tool to check your equipment, then confirm with your local authority.
A hood is required whenever cooking appliances generate grease-laden vapor, smoke, heat, or moisture that must be captured and exhausted. The trigger is the equipment and its output, not the type of business. Codes such as the International Mechanical Code and your local health and building departments set the specifics. Review the general ventilation requirements, then let a mechanical engineer and your AHJ confirm what your build needs.
A Type I hood captures grease-laden vapor and smoke from appliances like fryers, griddles, charbroilers, and open ranges. It uses listed grease-extracting baffle filters, a liquid-tight welded stainless steel construction, a grease drain and cup, and it connects to a fire-suppression system and a dedicated grease-duct exhaust. Type I is the hood most restaurants picture. A mechanical engineer sizes it to your specific cooking line.
A Type II hood handles heat, steam, moisture, and odor, but no grease. It sits over equipment like dishwashers, steamers, and some ovens and combi units. Because there is no grease, it does not need grease baffle filters, a grease duct, or fire suppression, so it is simpler and cheaper than a Type I. Confirm your equipment truly produces no grease before choosing Type II.
The dividing line is grease. Type I captures grease-laden vapor and smoke, so it requires baffle filters, a grease-tight duct, and fire suppression. Type II handles only heat, steam, and moisture with no grease, so it skips those systems. Put fryers and griddles under Type I; dishwashers and steamers under Type II. Misclassifying is a common and costly plan-review failure, so verify with your engineer and AHJ.
Grease-producing equipment such as fryers, griddles, charbroilers, open ranges, tilt skillets, and woks needs a Type I grease hood. Heat- and steam-producing equipment such as dishwashers, steamers, and some ovens needs a Type II hood. A handful of low-output countertop appliances may be exempt. Because exemptions vary locally, check your lineup with the do I need a hood tool and confirm with your AHJ.
Sometimes, but only with limited, low-output equipment that produces no grease-laden vapor, such as certain countertop ovens, microwaves, or ventless appliances listed for hoodless use. Any real grease cooking, like frying or charbroiling, requires a Type I hood. Some ventless fryers with built-in filtration and suppression exist, but they must be listed and locally approved. Your health and building departments have the final say.
Rarely as a simple swap. A Type I hood needs liquid-tight welded construction, grease baffle filters, a grease drain, a dedicated grease duct, and fire suppression, none of which a Type II provides. In practice, converting means replacing the hood and often the ductwork and suppression too. If you are adding grease cooking, plan on a new Type I installation designed by a mechanical engineer.
It depends on the oven. Solid-fuel (wood or coal) and many gas or deck pizza ovens produce grease and smoke and require a Type I hood, often with extra provisions for solid fuel. Some electric countertop or listed ventless pizza ovens may not. The manufacturer's listing and your local code decide it. Confirm the specific model with your engineer and AHJ before you buy.
You need a Type I hood whenever an appliance produces grease-laden vapor or smoke: fryers, griddles, charbroilers, open-burner ranges, woks, tilt skillets, and solid-fuel cooking. The presence of grease, not the fuel or size, is what triggers it. Type I brings baffle filters, a grease duct, and fire suppression. Check your lineup with the do I need a hood tool and let your AHJ confirm.
A Type II hood is required over equipment that releases significant heat, steam, or moisture without grease, most commonly commercial dishwashers, plus steamers and some ovens. It clears humidity and heat to protect the space and comfort, but it has no grease or fire-suppression provisions. If any grease is involved, you need Type I instead. Your engineer matches hood type to each appliance.
A commercial kitchen hood is the canopy and exhaust system that captures heat, smoke, grease, steam, and odor above cooking equipment and carries it outdoors through ductwork and a fan. Type I hoods handle grease with baffle filters and fire suppression; Type II handle heat and steam only. A properly sized hood keeps the kitchen safe, comfortable, and code-compliant. Sizing is an engineered calculation, not a guess.
The hood canopy overhangs the cooking line and captures the rising thermal plume of hot air, smoke, and vapor. An exhaust fan pulls that air through grease baffle filters (on Type I), up a duct, and out through a roof or wall fan. As air leaves, replacement (make-up) air must enter to keep the room balanced, as our ventilation guide explains. Capture depends on correct overhang, height, and airflow, all engineered values.
There is no single number; airflow depends on hood style, appliance duty (light, medium, heavy, extra-heavy), and hood length. Heavier cooking like charbroiling needs far more CFM per foot than a light-duty oven. Wall canopies also differ from island hoods. Estimate a starting point with our hood CFM calculator, then have a mechanical engineer set the final value for your equipment and hood.
CFM is generally figured per linear foot of hood based on the heaviest cooking duty beneath it and the hood style, with adjustments for overhang and mounting height. Duty ranges from light (ovens) to extra-heavy (solid fuel), each with its own airflow factor. Get a working estimate from our hood CFM calculator, but a mechanical engineer performs the code-compliant calculation your plans will be judged against.
Sizing covers two things: physical dimensions and airflow. The hood must overhang the cooking equipment on the open sides (commonly about six inches per side) and be deep enough to capture the plume, with mounting height controlled. Airflow (CFM) is then set by the appliance duty and hood length. Get a starting estimate from our CFM calculator, but an engineer produces the final sizing for permit.
The hood should be long and deep enough to fully cover your cooking line plus the required overhang on exposed sides, so it captures the plume before it escapes. A hood that is too short or too shallow spills grease and smoke regardless of fan power. Measure your equipment footprint, add the code overhang, and estimate airflow with our hood CFM calculator before an engineer finalizes it.
Big enough to overhang the cooking equipment on all open sides, typically around six inches beyond the appliance edge, and deep enough to capture the rising plume. Length matches your cooking line; depth and mounting height follow the hood listing. Undersized hoods fail to capture no matter how much air you move. Confirm the exact overhang and dimensions required with your AHJ and engineer.
Standard wall-mount canopy hoods are commonly around 48 to 54 inches deep, though depths vary by manufacturer, model, and the equipment being covered. Island hoods are deeper because they capture from both sides. The key is that the hood fully overhangs the appliances so the plume is captured. Match depth to your specific cooking line and confirm with the manufacturer and your engineer.
Cost varies widely with hood type, length, materials, and whether ductwork, an exhaust fan, make-up air, and fire suppression are included. A Type I system with all components installed is a significant capital line, well above the price of a Type II hood alone. Because installation and code work drive much of the total, get itemized quotes from local hood contractors rather than relying on a single figure.
Installation is often as costly as the hood itself. It includes hanging the hood, running and welding grease duct through the roof, setting the exhaust fan, adding make-up air, wiring, and commissioning the fire-suppression system, plus permits and balancing. Building conditions, roof runs, and local labor swing the price heavily. Get itemized bids from licensed hood and mechanical contractors for your specific space.
A Type I grease hood costs more than a Type II because it includes welded liquid-tight construction, baffle filters, a grease duct, an exhaust fan, make-up air, and fire suppression. The hood shell is only part of the total; the duct, fan, suppression, and installation usually cost more than the canopy. Pricing is very market-dependent, so collect several local quotes before budgeting.
A Type II hood is generally cheaper than a Type I because it has no grease filters, grease duct, or fire suppression, just a canopy, duct, and fan for heat and steam. Even so, ductwork, the fan, make-up air balancing, and installation add up. Because prices vary by region and building, get itemized quotes from local contractors rather than budgeting from a single number.
Installation is a licensed trade: the hood is hung and leveled, welded grease duct is run to a roof or wall exhaust fan, make-up air is added, electrical is wired, the fire-suppression system is installed and linked to gas/power shutoffs, and the system is balanced and inspected. It requires permits and coordination among mechanical, electrical, and fire trades. This is not a DIY job; hire qualified hood contractors.
Licensed commercial hood or mechanical (HVAC) contractors install the hood and ductwork, often coordinating with a certified fire-suppression company for the Ansul-type system and with electricians for wiring and interlocks. A mechanical engineer typically stamps the design for permit. Choose contractors experienced with commercial kitchen exhaust and NFPA 96, since AHJ inspection is required before you can open.
The hood itself draws little; the load comes from the exhaust fan motor, any make-up air unit, and hood lights. Fan motors range from a fraction of a horsepower to several horsepower depending on airflow and static pressure, so amperage varies a lot. Sizing the circuit is an electrical calculation based on the actual fan and make-up air equipment. Your electrician and engineer determine the required circuits.
The hood is suspended from the building structure with threaded rod and hangers rated for its weight, leveled, and set at the listed mounting height above the cooking surface so it captures the plume without spilling. Duct connections must be welded and grease-tight. Because weight, height, and clearances are code-controlled and life-safety related, hanging a commercial hood is a job for experienced hood installers, not general handymen.
Balancing means measuring and adjusting exhaust and make-up air so the kitchen runs at a slight negative pressure, capturing smoke and grease without slamming doors or starving gas appliances of air. A technician sets fan speeds and dampers and verifies airflow with instruments. Make-up air typically replaces roughly 80 to 90 percent of exhaust. This is done at commissioning by a balancing contractor, not by feel.
Broadly, the hood must match the cooking duty (Type I for grease, Type II for heat), overhang the equipment, be built and ducted to code, move enough air, be paired with make-up air, and, for Type I, include a listed fire-suppression system and regular NFPA 96 cleaning. Details vary locally. Review the general requirements overview, then have a mechanical engineer and your AHJ confirm the specifics.
Yes. Type I is the code term for a grease hood: the hood designed to capture grease-laden vapor and smoke. It uses grease-extracting baffle filters, welded liquid-tight construction, a grease drain, a dedicated grease duct, and a fire-suppression system. If your equipment makes grease, you need a Type I. Type II hoods, by contrast, handle only heat and steam and are not grease hoods.
Hood lighting and receptacles may require GFCI protection depending on their location and the electrical code, especially near sinks or wet areas, but the requirement is set by the electrical code and your local inspector, not the hood itself. Fan motors and control circuits have their own protection requirements. An electrician designs the hood's electrical to the current code and your local amendments.
Wiring ties together the exhaust fan, make-up air unit, hood lights, and control panel, and interlocks them with the fire-suppression system so that when suppression discharges it shuts off gas and/or electric power to the appliances and, per design, activates fans. This is a licensed electrical job coordinated with the fire-suppression installer and engineer. It must pass inspection before use; do not attempt it yourself.
A Type I hood is a stainless steel canopy over the cooking line with a row of angled metal baffle filters visible along its face, a grease trough or cup at the bottom edge, and fire-suppression nozzles aimed at the appliances and duct. You will also see the suppression piping and a pull station nearby. The seamless welded body distinguishes it from a lighter Type II hood.
A hood liner is a listed, grease-tight stainless steel insert used when a hood is built into a custom or decorative enclosure, providing the code-compliant capture surface, baffle filters, grease drainage, and fire-suppression mounting inside a non-listed shell. It lets designers hide the working hood behind millwork while keeping the functional parts to code. Liners are common in display kitchens and must still be engineered and inspected.