Every restaurant owner should know fire code guidelines for their commercial kitchen, especially when it comes to their exhaust system (range hoods). If these are not properly cleaned and inspected on a regular basis, this can result in a serious fire, damaging your entire kitchen and restaurant. If you do not know your state’s commercial kitchen fire codes, just read below (click on the link at the end of the summary to read about it in more detail).

Hood Ventilation System Ducts and Exhaust Equipment:

Ducts must be protected against corrosion.

Grease duct materials need to be galvanized 16 gage, stainless 18 gage.

Grease duct joint, seams or penetrations must be continuously welded or brazed.

Duct-to-exhaust fan connection must be flanged, gasket and bolted.

Vibration isolation must be listed as non-combustible packing in metal sleeve joint or listed as coated-fabric flexible duct connector, connected only at the duct to fan inlet or outlet connection.

Grease duct bracing and support must be non-combustible material and securely attached to the structure, bolts, screws, rivets. Fasteners must not penetrate the duct walls.

Velocity must not be less than 500 feet per minute.

Grease duct clearances must not be less than 18” from combustibles or 3” from gypsum wallboard and it must be attached to noncombustible structures.

Termination above roof must not be less than 40” above the roof.

Termination through exterior wall must not create a public nuisance (especially not where protected openings are required and not within 3’ of other exterior openings).

Termination location must be 10’ horizontally from buildings, property lines, air intake openings and 10’ above grade (exception would be: 5 feet if air discharges away from such locations).

Ducts Serving type II Hood:

Ducts need to be protected against corrosion.

Opening location of the duct must be 10’ horizontally from buildings and property lines.

Termination location of the duct must be 10’ horizontally away from & 2’ above outdoor mechanical and gravity air intake openings.

Exhaust openings of the duct must be located so as not to create a nuisance, neither should they be directed onto walkways.

Exterior exhaust outlets of ducts must meet IBC requirements for exterior wall opening protective.

Ducts must be constructed of rigid metallic materials.

Exhaust Equipment:

Exhaust fans serving Type I hoods must be constructed as required for a grease duct or per UL 762, fan located outside the air stream.

Exhaust fan discharge should not impinge on roof, equipment, appliances or parts of structure. Vertical discharge fans must have an approved drain outlet at lowest point of housing and grease reservoir.

Exhaust fan mounting must consist of up-blast fans that are hinged and supplied with a flexible, weatherproof electrical cable to permit inspection and cleaning. Ductwork needs to extend 18” above the roof surface.

Clearances of the exhaust equipment need to maintain 18” clearance from combustibles.

Termination of the exhaust must be 2’ between the vertical discharge fan and parapets if fan housing is no taller than the parapet.

Commercial Kitchen Hoods General:

Hoods must be designed to capture & confine cooking vapors & residues & must be on during cooking operations.

Type I & Type II Hood Requirements:

Type I hoods must be installed where cooking appliances produce grease or smoke (griddles, fryers, broilers, ovens, ranges and wok ranges).

Operation: Type I hood systems must be designed and installed to automatically activate the exhaust fan whenever cooking is happening. The activation of the exhaust fan must work through an interlock with the cooking appliances, by means of heat sensors or other approved methods.

Type II hoods must be installed where cooking or dishwashing appliances produce heat, steam or products of combustion and do not produce grease or smoke.

Domestic cooking appliances used for commercial purposes must be provided with Type I or Type II hoods as required for the type of appliances and processes proposed.

Type I hoods over extra-heavy duty cooking appliances used for commercial cooking must discharge to an exhaust system that is independent of other exhaust systems.

Where vented fuel burning appliances are located in the same area as the hood, provisions shall be made to prevent the hood system from interfering with the appliance’s operation.

Type I hood must be made of steel 18 gage and stainless 20 gage in thickness.

Type II hood must be made of steel 22 gage, stainless 24 gage, copper 24 oz/sq. ft.

Type I hoods must be secured by non-combustible supports.

Type I hoods: external hood joints, seams, & penetrations must be made with a continuous external liquid, tight weld or braze.

Type II hoods: Joints, seams and penetrations must be sealed on the interior of the hood and must provide a smooth surface that is readily cleanable and watertight.

A hood must be designed to provide for thorough cleaning of the entire hood. Grease gutters need to drain to allow access for cleaning.

Type I hoods must not be less than 18” from combustibles. Clearance from gypsum wallboard attached to noncombustible structures is not required if a smooth, cleanable, non-absorbent, and non-combustible material extends 18” beyond the hood.

The hood must extend a minimum of 6 inches past the edge of the appliances and must not be more than 4 feet above the surface of the appliances. The front edge of the hood may be flushed with the appliances when the rear wall of the appliance space is constructed of noncombustible materials.

Commercial food service hoods must exhaust a minimum net quantity of air as determined by the multipliers below based on the length of the hood. The heaviest duty appliance type covered by the hood must be used for the entire hood.

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