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Commercial Kitchen Hood Code Requirements

Commercial Kitchen Hood Code Requirements

Last updated on 4/22/2021

Every kitchen must adhere to a variety of rules, regulations, and codes to operate legally. When it comes to kitchen hoods, these regulations are essential for preventing hazards and maintaining air quality in a commercial setting. Below we'll investigate what a kitchen hood is, how they work, and the various code requirements you should follow to create a safe workplace.

What Is a Commercial Kitchen Hood?

A kitchen hood is a device that is installed above a cooking surface or cooking appliance and helps to ventilate the kitchen. Also known as range hoods or exhaust hoods, they remove hazardous particles from the air and maintain a safe working environment. They also maintain the air quality of your kitchen and help to reduce buildup of smoke, grease, and other similar particles, making cleaning and maintenance easier for your staff.

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Types of Kitchen Hoods

There are two types of commercial kitchen hoods, known as Type I and Type II hoods. These hoods are distinguished by the types of materials they filter out of the air.

  • Type I Hoods: Also known as grease hoods, Type I hoods are designed to remove heat, smoke, and airborne grease. These types of hoods are often found over appliances such as fryers, broilers, grills, and ovens.
  • Type II Hoods: Sometimes called condensate hoods, Type II hoods work to remove steam, vapor, and other moisture from the air. Some Type II hoods even remove odors. They are often found on top of coffee machines, commercial dishwashers, and certain pizza ovens. Additionally, these types of hoods often lack a grease filter, so they shouldn’t be used interchangeably with Type I hoods.

How Do Kitchen Hoods Work?

Kitchen hoods are installed above your cooking appliances. A fan powered by a motor spins as you cook, pulling air and any hazardous particles into the machine. The air travels through ductwork attached to the machine, which then displaces it outside. Kitchen hoods should be outfitted with a make-up air device to ensure that any air filtered out of the building is replaced.

To properly maintain and upgrade your ventilation system, be sure to shop from our selection of ventilation and range hood parts.


Commercial Kitchen Hood Code Requirements

Commercial Kitchen Hood Code Requirements

To legally operate your kitchen, you must adhere to local commercial kitchen hood code requirements. While most states and municipalities follow the International Mechanical Code as the basis for their regulations, certain specifications and code requirements can vary depending on where you live. Before making any decisions on how to establish your exhaust system, it’s essential to check with local officials.

Design and Layout Specifications

When planning your kitchen, you should consider regulations regarding the layout, construction, and design of your kitchen's exhaust system. Failure to do so can result in safety hazards, failed inspections, and costly renovations. To make sure your equipment is properly installed, be sure to keep the following requirements in mind:

  • Meet the minimum overhang requirement: The inside lower edge of commercial hoods should overhang or extend no less than 6 inches beyond the edge of the cooking surface or appliance it is installed above.
  • Stay within the elevation range: The vertical distance above the cooking surface should not exceed 4 feet.
  • Install fire suppression systems: It is required that all commercial appliances under a Type I hood be provided with an approved automatic fire suppression system. This system should comply with the International Building Code and International Fire Code.
  • Use the proper equipment: Hoods intended for use above extra-heavy-duty equipment should not be used above heavy-, medium-, and light-duty equipment.

Type I Hood Requirements

Due to the significant differences between Type I and Type II hoods, each type is subject to its own unique set of rules and regulations. Since Type I hoods collect flammable materials, they should be constructed, designed, and laid out specifically in your kitchen. Below, we’ll investigate the requirements for Type I hoods:

  • Avoid combustibles: Install your hood at least 18 inches away from combustibles.
  • Use approved materials: Any hood in the kitchen should be made of steel with a minimum thickness of 0.0466 inches of stainless steel with a minimum thickness of 0.0335 inches.
  • Label your hood: Each hood should include a label indicating the minimum exhaust flow rate in CFM (cubic feet per minute) per linear foot.
  • Construct appropriate support: Make sure that each hood is secured in place by noncombustible supports.
  • Protect joints, seams, and penetrations: Any external joints, seams, and penetrations should be made from continuous external liquid-tight weld or braze to the lowest outermost perimeter of the hood.
  • Keep joints sealed: Internal joints are not required to be welded or brazed but should be sealed so that grease cannot escape.

Elevation Requirements for Type I Hoods

All Type I hoods should be outfitted with a grease filter. Its height above the cooking surface determines how well it operates and depends on the type of appliance below it. These height requirements are as follows:

  • 1.5 feet above: Cooking surfaces without an exposed flame
  • 2 feet above: Cooking surfaces with an exposed flame and burners
  • 3.5 feet above: Appliances with exposed charcoal or a charbroiler

Type II Hood Requirements

Since Type II hoods remove condensation and odors from the air, they aren’t required to follow the same code requirements as Type I hoods. Nevertheless, they fulfill an important function in the kitchen and must be constructed properly. Be sure to take note of the following code requirements as you prepare your Type II hood:

  • Construct sturdy supports: Hood supports should be able to hold the load of the hood, unsupported ductwork, effluent load, and possible weight of any personnel working on the hood.
  • Seal joints internally: Joints, seams, and penetrations for Type II hoods should be sealed on the interior of the hood. The interior should provide a smooth surface that is easily cleanable and water-tight.
  • Use appropriate materials: Type II hoods should be constructed from steel with a minimum thickness of 0.0296 inches, stainless steel with a minimum thickness of 0.0220 inches, and copper sheets weighing at least 24 oz. per square foot.

Grease Filtration Guidelines

The grease and smoke filtered by Type I hoods can easily build up and become a hazard if your exhaust system isn’t up to code. To keep your kitchen safe, adhere to the following code requirements:

  • Use non-combustible materials: Makeup air ducts within 18 inches of a Type I hood should be non-combustible.
  • Protect joints and seams: Grease duct joints and seams should be made with continuous liquid-tight weld or braze materials.
  • Overlap joints: To prevent ledges or other obstructions from collecting grease or interfering with drainage, overlapping joints should be installed.
  • Construct dependable supports: Grease duct supports should be made from non-combustible materials, securely attached to the structure, and designed to carry gravity and seismic loads within stress limitations.
  • Separate grease from cooking surfaces: Grease duct systems attached to Type I hoods should be at least 18 inches from combustible materials or appliances.
  • Use correct materials: Ducts attached to Type I hoods should be made from steel with a maximum thickness of at least 0.0575 inches, or stainless steel at least 1.045 inches thick.

Condensation Filtration Guidelines

Designing your ductwork and air filtration system with condensation in mind can help to prevent leaks in your kitchen and ensure that air is filtered correctly. To create an efficient exhaust system, keep the following requirements in mind for any ventilation system attached to a Type II hood:

Commercial Cooking Without a Hood
  • Displace air properly: Any air filtered from your kitchen should be discharged outdoors at a point where it will not cause a public nuisance.
  • Seclude exhaust outlets: The location of exhaust outlets should be located beyond the required minimum distance from guests, staff, and other nearby businesses.
  • Protect exhaust outlets: Exhaust openings should be protected with corrosion-resistant screens, louvers, or grilles. The openings of these appliances should range from 1/4 inch to 1/2 inch.
  • Protect exposed ductwork: Any ductwork exposed to outside air or a corrosive environment should be protected against corrosion.
  • Don't penetrate ductwork: Bolts, screws, rivets, and other fasteners should not penetrate wall ducts.
  • Use rigid materials: Ducts serving Type II hoods should be made from rigid metallic materials.

Cleaning Specifications

Regularly cleaning and maintaining your kitchen exhaust system helps to reduce the risk of fires, equipment shutdowns, and other emergencies. To make sure you can easily clean your system, choose a hood system design that is accessible for maintenance and cleaning by following these code requirements:

  • Keep cleaning in mind: Your kitchen hood should be designed to allow thorough cleaning of the entire hood.
  • Seal joints: To avoid leakage and make sure that cleaning is easy, ensure that any joints and seams are tightly sealed.
  • Protect against leftover grease: Provide grease troughs and drip pans to catch any leftover grease and easily dispose of it.
  • Collect and clean grease: Ensure that grease gutters drain to an approved collection receptacle that is also regularly cleaned.
  • Place openings sparingly: Grease ducts should only have openings where required for operation and maintenance.
  • Keep openings sealed: Openings should be equipped with tight-fitting doors as thick as the duct and sealing materials shall be rated for not less than 1500 degrees Fahrenheit.

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Commercial Cooking Without a Hood

In most commercial kitchens, a hood is required to maintain a safe workplace and comply with local regulations. However, there are some instances where a kitchen may need to operate without one. Depending on their size, power consumption, and heat output, certain kitchen appliances may be exempt under your local health code, allowing them to operate without a kitchen hood. For safety reasons, you must check with local officials before deciding to purchase or operate any equipment without a hood.

Below, we’ve listed some of the most common exempt appliances:

  • Under-the-counter dishwashers
  • Light-duty microwave ovens
  • Toasters
  • Popcorn machines
  • Hot dog cookers
  • Coffee makers
  • Rice cookers
  • Holding cabinets
  • Certain countertop steamers

Frequently Asked Questions

Do I Need a Hood in my Commercial Kitchen

While the International Mechanical Code is thorough and covers a variety of topics, you may have questions that they don’t directly cover. Below, we’ve compiled some of the common questions asked about commercial kitchen hood code requirements and how they apply to different appliances in your kitchen.

Does a Convection Oven Require a Hood?

Most commercial convection ovens are required to be under a Type I hood, but there are some exceptions. Some ventless convection ovens are designed with a hood built into them, eliminating the need for a commercial hood.

Does a Pizza Oven Need a Hood?

Yes, commercial pizza ovens are required to be under a hood. However, due to the many different types of pizza ovens available on the market, it’s important to determine whether your pizza oven requires a Type I or Type II hood.

Does a Steam Kettle Need to Be Under a Hood?

In general, most steam kettles should be kept under a hood. Since these kettles produce steam, it’s important to make sure they are located under a Type II hood. It's important to note that some microwave steamers don’t require a floor drain or water supply, meaning that they don’t need to be placed under a hood.


Fully understanding commercial kitchen code requirements can be difficult due to the high volume of requirements that exist and the format they are available in. Using the information above, you can build an understanding of what you have to do to establish a safe and legal exhaust system in your kitchen. Before finalizing any plans, be sure to check with your local authorities to make sure everything is correct.

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