Commercial Kitchen Hood Installation Requirements and Grease Trap Cleaning Frequency

Updated October 20264 min readBy the KitchenScope team

For restaurant owners and kitchen managers, two systems cause more inspection trouble than almost anything else: the exhaust hood over the cook line and the grease trap under or behind the kitchen. Commercial kitchen hood installation requirements come mainly from NFPA 96, the fire code standard for commercial cooking ventilation, together with the mechanical and fire codes your village or the City of Chicago has adopted. Grease trap rules come from the local sanitary district or municipality.

This guide walks through hood types, what a compliant installation includes, the NFPA 96 inspection and cleaning schedule, grease trap cleaning frequency and the habits that make inspections routine. Details vary by jurisdiction, so always confirm specifics with your building department, fire department and sanitary authority before you buy equipment or sign for work.

Type I and Type II hoods: which one you need

The hood type follows the equipment under it. Whether a specific appliance needs a Type I hood is decided under the code your jurisdiction uses and by the plan reviewer, so bring your full equipment list, with model numbers, to the design stage.

Type I and Type II hoods

	Type I	Type II
Purpose	Grease and smoke	Heat, steam and vapor
Typical equipment	Fryers, griddles, charbroilers, ranges, woks	Many dishwashers and some ovens
Grease filters or baffles	Yes	No
Welded grease duct	Yes	No
Fire suppression	Yes	Not usually

Final hood type is set by the adopted code and the plan reviewer.

Commercial kitchen hood installation requirements

Every jurisdiction reviews hood plans a little differently, but the same core requirements show up in almost every Chicago-area project.

Hood and grease duct

A hood listed for its use, sized to overhang the cooking equipment as the code and listing require.
A liquid-tight, continuously welded grease duct of the steel gauge NFPA 96 specifies, sloped to drain back toward the hood, with cleanout access along the run.
Required clearances from hood and duct to combustible materials, or a listed enclosure or wrap.

Fan, makeup air and fire suppression

An exhaust fan rated for grease exhaust, with the discharge located away from air intakes and roof edges as required.
Makeup air sized to replace what the hood exhausts, so doors do not whistle and burners do not starve.
A fire suppression system over the cooking surfaces, plenum and duct, with automatic fuel or power shutoff.

Permits and inspections

Expect permits and inspections from the building department, and usually a fire department review of the suppression system. Inspectors look at the hood, duct, fan and suppression as one system.

Commercial Kitchen Projects — before — Commercial Kitchen Projects, before and after: the same kitchen with a new hood line and stainless equipment.

Commercial Kitchen Projects — after — Commercial Kitchen Projects, before and after: the same kitchen with a new hood line and stainless equipment.

Installing a commercial hood: the usual sequence

Hood projects run smoothest when design, permits and trades are lined up before anything is ordered.

Finalize the equipment listList every cooking appliance with model numbers, fuel type and position on the line.
Design the systemSize the hood, duct route, exhaust fan and makeup air, and lay out the suppression coverage.
Submit for permitsFile drawings with the building department, and the suppression design with the fire authority where required.
Install and weldHang the hood, weld and support the duct, set the fan and makeup air unit, and wire controls.
Inspect and testComplete rough and final inspections, test the suppression system and confirm the fuel or power shutoff works.

Planning this in your kitchen?We measure, explain the options and send a written quote.

Call (708) 400-7049 Request a callback

NFPA 96 hood cleaning frequency

NFPA 96 sets inspection frequencies for the exhaust system based on the type and volume of cooking, and the system must be cleaned when inspection finds grease buildup. These are inspection intervals: a busy kitchen may find that every inspection calls for cleaning, while a light-use kitchen may not. Your fire inspector or insurer can also ask for a tighter schedule.

NFPA 96 exhaust system inspection frequency

Cooking operation	Examples	Inspection interval
Solid fuel	Wood or charcoal cooking	Monthly
High volume	24-hour operations, charbroiling, wok cooking	Quarterly
Moderate volume	Kitchens between high and low volume	Semiannually
Low volume	Churches, day camps, seasonal businesses, senior centers	Annually

Source: NFPA 96. Clean whenever inspection finds grease buildup.

What a proper hood cleaning includes

A hood cleaning that satisfies a fire inspector covers the whole exhaust path, not just the visible canopy: filters, plenum, the full duct run to the roof and the exhaust fan. The cleaning company should leave a certificate or label on the hood showing the date and what was cleaned, and report areas they could not reach. Keep those records with your fire suppression inspection reports.

Between professional cleanings, staff should clean or swap baffle filters regularly, often daily or weekly depending on volume, and empty grease cups. Dirty filters reduce airflow and let more grease into the duct.

Commercial Kitchen Hood Installation — before — Commercial Kitchen Hood Installation, before and after: a new stainless type I exhaust hood with fire suppression nozzles over the cook line.

Commercial Kitchen Hood Installation — after — Commercial Kitchen Hood Installation, before and after: a new stainless type I exhaust hood with fire suppression nozzles over the cook line.

Grease trap cleaning frequency

There is no single answer, because it depends on the size of the trap or interceptor and how much grease goes down the drains. Many municipal programs use a version of the quarter rule: the trap must be cleaned before fats, oils, grease and settled solids take up about 25 percent of its depth.

The rules that actually apply to you come from your local sanitary district or village. In the Chicago area that can mean requirements from the municipality, the regional wastewater district or both. They may set a minimum pumping interval, require a licensed hauler and ask you to keep a maintenance log on site.

Typical grease trap service patterns

Trap type	Where it sits	Common service pattern
Small under-sink trap	At the fixture	Weekly or more often in busy kitchens
Any trap or interceptor	Anywhere on the line	Before grease and solids reach about 25 percent of depth
Large in-ground interceptor	Outside or below grade	Often monthly to quarterly

Your sanitary authority's limit, commonly the quarter rule, takes priority over any pattern.

Signs the grease trap needs service sooner

A schedule is a starting point; your kitchen tells you when it is not enough.

Slow sinks or floor drains, or water backing up into floor sinks.
Sewer or rancid smells near the trap or the back door.
Grease visible on the outlet side or in the downstream manhole.
A notice from the village or sanitary district about fats, oils and grease in the sewer line.

Keeping inspections smooth

The restaurants that pass inspections without drama usually share the same habits.

One binder or digital folder with hood cleaning certificates, fire suppression reports, grease trap pumping receipts and permit documents.
Plates scraped and pans wiped before washing, and strainers in every sink.
Used fryer oil collected for recycling instead of poured down the drain.
A check of hood and suppression coverage before any new or moved cooking equipment arrives; an appliance outside the capture area or nozzle coverage is a common reason for a failed inspection.

Frequently asked questions

Does every restaurant need a Type I hood?

Not every one. It depends on the equipment. Kitchens that only reheat or use certain listed ventless appliances may not, but anything producing grease-laden vapors usually does. Your plan reviewer makes the final call.

How often should a commercial kitchen hood be cleaned?

NFPA 96 ties inspection frequency to cooking volume: monthly for solid fuel, quarterly for high volume, semiannually for moderate volume and annually for low volume. Clean whenever inspection finds buildup.

How often should a grease trap be cleaned?

Often enough that grease and solids never exceed the limit your sanitary authority sets, commonly about a quarter of the trap's depth. For many kitchens that means weekly for small traps and monthly to quarterly for large interceptors.

Who sets grease trap rules in the Chicago area?

Requirements come from the local sanitary district and the municipality. Check with your village or the City of Chicago and the wastewater authority that serves your address.

Can I install a commercial hood without a permit?

No. Commercial hood systems are typically reviewed and inspected by the building department, and the fire suppression system by the fire department or fire prevention bureau.

Can I use enzymes or additives instead of pumping the grease trap?

Many sanitary authorities restrict or prohibit additives that break up grease, because the grease can re-form further down the sewer line. Check your local rules before using any additive.