What Actually Happens During a Commercial Hood Cleaning?
Most restaurant owners schedule hood cleaning because they have to — not because they know what the service actually covers. Here is exactly what a full NFPA 96 compliant cleaning involves from setup to compliance certificate.
In This Guide
- Before the Cleaning Begins: Setup & Protection
- The Cleaning Sequence: Step by Step
- Step 1–2: Hood Canopy and Filter Removal
- Step 3–4: Degreaser and Pressure Washing
- Step 5: Ductwork Cleaning
- Step 6: Rooftop Fan Service
- Step 7: Grease Collection and Disposal
- After the Cleaning: Documentation and Compliance
- What to Expect on Service Day
- FAQ
What a Full NFPA 96 Cleaning Covers
Before the Cleaning Begins: Setup & Protection
A professional hood cleaning crew arrives after your kitchen closes — typically late at night or early morning. Before any cleaning chemistry touches your kitchen, the crew's first priority is protection and documentation.
- →Kitchen protection: Every cooking surface, piece of equipment, and exposed area near the hood is covered with heavy-duty poly plastic sheeting. This prevents degreaser and hot wash water from contaminating your equipment, food prep surfaces, or stored food.
- →Utilities staged: Hot water supply is connected (from your kitchen utility or the truck tank), and drainage collection is set up to capture all wash water and displaced grease. A compliant company never lets contaminated water drain into your restaurant's systems or onto the rooftop.
- →Before photos taken: Before any cleaning begins, before photos are taken of every area that will be cleaned — hood interior, duct access points, rooftop fan. These photos are part of your service documentation and show baseline grease levels.
- →Access verification: The technician confirms access to all parts of the system: duct access panels, rooftop access, and any areas that may have been installed without adequate cleaning access. Limited-access areas are documented in the service report.
The Cleaning Sequence: Step by Step
An NFPA 96 compliant hood cleaning follows a specific sequence — from the cooking surface up through the system to the rooftop. Each component is addressed in turn so displaced grease moves toward collection points, not back into areas already cleaned.
Step 1–2: Hood Canopy and Filter Removal
Grease filter removal
Grease filters are removed from the hood opening and set aside. Removing them gives direct access to the plenum chamber and allows the filters to be pressure washed separately — cleaning them in place leaves the surrounding surfaces contaminated.
Hood canopy surface cleaning
The exterior and interior surfaces of the hood canopy are cleaned. With filters removed, the full interior is accessible. Commercial-grade degreaser is applied to all surfaces and allowed to penetrate before washing. The canopy interior and surrounding hood shell are pressure washed and wiped down.
Step 3–4: Degreaser Application and Pressure Washing
Degreaser application to all surfaces
Commercial-grade alkaline degreaser is applied to all interior hood surfaces, the plenum chamber, and the accessible ductwork. The chemistry requires contact time to emulsify accumulated grease — the technician applies it and allows it to penetrate before washing begins. Rushing this step produces incomplete results.
Hot-water pressure washing
High-pressure hot water is used to wash all surfaces clean. A trained technician works methodically through the hood canopy, plenum, and duct interior — pushing displaced grease toward collection points at the bottom of the system. Hot water activates the degreaser chemistry and carries grease out of the system.
Step 5: Ductwork Cleaning
Full duct interior cleaning
The ductwork is cleaned from both ends when accessible — from inside the hood at the bottom and from the rooftop at the top. For long duct runs, technicians use flexible pressure washing extensions to reach the full interior length.
This is the most critical and most commonly skipped step by non-compliant operators. The ductwork contains more accumulated grease than the visible hood in most commercial kitchens, and a fire that reaches an uncleaned duct can travel to the rooftop before the suppression system stops it. NFPA 96 specifically requires the full duct interior — not just the accessible portions.
How to tell if your ductwork is actually being cleaned
Any service that does not include rooftop access is not cleaning the ductwork to the standard. Ask your technician for photos of the duct interior from the access points and the rooftop fan housing. If they cannot provide these, they did not access those areas.
Step 6: Rooftop Exhaust Fan Service
Rooftop fan and housing
On the rooftop, technicians access the exhaust fan — which is hinged on a UL-listed upblast fan, or removed on other configurations — and clean the fan blades, fan housing interior, and surrounding curb area. The rooftop fan accumulates grease from the full exhaust path and is one of the most significant fire hazards in the system. A grease-packed fan is both a fire risk and an efficiency problem: clogged fan blades reduce exhaust airflow and drive up cooking temperatures and energy costs.
Step 7: Grease Collection and Proper Disposal
Grease water collection and disposal
All wash water — heavily contaminated with displaced grease and cleaning chemistry — must be collected and properly disposed of. A responsible company never lets contaminated water drain into the rooftop surface, building downspouts, or storm drains. The collected waste is transported and disposed of at an approved facility. This is an environmental compliance requirement as well as a professional standard.
After the Cleaning: Documentation and Compliance
Once the cleaning is complete, the protective plastic is removed and the kitchen is restored to its pre-service condition. The final phase of every compliant service is documentation.
- ✓After photos: After photos are taken of every area that was cleaned — matching the before photos — so you have visual confirmation of the work performed and a clear before/after comparison.
- ✓Final walkthrough: The lead technician conducts a final walkthrough with the on-site contact to confirm all areas were addressed, protective sheeting has been removed, and the kitchen is ready for the next service.
- ✓NFPA 96 compliance sticker: An NFPA 96 sticker is applied to the hood documenting the date of service and the company that performed it. This is the primary compliance indicator that fire marshals and health inspectors look for.
- ✓Service report: You receive a written service report documenting all areas cleaned, the technician's certification, the date of service, and any access limitations or areas that could not be fully cleaned.
- ✓Compliance certificate: A compliance certificate is provided confirming the service was performed to NFPA 96 standards. This is the document your insurance carrier and fire marshal ask to see as proof of compliant maintenance.
What to Expect on Service Day
A few things to prepare for and expect when your service is scheduled:
Schedule Your NFPA 96 Cleaning
Core Hood Cleaning provides full NFPA 96 service for San Diego restaurants — covering the entire exhaust path with before/after photos and full compliance documentation on every visit.
Frequently Asked Questions
What does a commercial hood cleaning include?
A full NFPA 96 compliant cleaning covers the entire exhaust path: hood canopy, grease filters (removed and washed separately), plenum chamber, all ductwork, and the rooftop exhaust fan. It also includes setup protection, before and after photos, and a compliance certificate with NFPA 96 sticker.
How long does a commercial hood cleaning take?
Most cleanings take 2–5 hours depending on system size, number of hoods, duct run length, and grease accumulation level. Systems on a regular cleaning schedule take less time than neglected systems. Service is performed after closing to avoid interrupting operations.
Does the hood cleaning cover the rooftop?
Yes — a full NFPA 96 compliant cleaning must include the rooftop exhaust fan. Technicians clean the fan blades, housing interior, and surrounding curb area. Any service that does not include rooftop access is not providing a fully compliant cleaning.
What documentation do I receive after a hood cleaning?
After each service you receive: a service report, before and after photos, a statement of NFPA 96 compliance, and an NFPA 96 compliance sticker on the hood. This is the documentation fire marshals and health inspectors ask for.
What is the difference between a full hood cleaning and just changing the filters?
Filter replacement only addresses the grease filters at the hood opening. A full NFPA 96 cleaning covers everything behind and above the filters — the plenum, all ductwork, and the rooftop fan. Filter-only service is not an NFPA 96 compliant cleaning.
What is the degreaser used during hood cleaning?
Professional hood cleaning uses commercial-grade alkaline degreaser — much stronger than consumer products. It is applied to all interior surfaces, allowed to penetrate, then pressure washed off with hot water. All resulting wash water must be collected and properly disposed of.
Can I stay in the restaurant during a hood cleaning?
No — hood cleaning uses strong chemical degreasers and high-pressure hot water that produce fumes making the kitchen unsafe to occupy during service. The restaurant can open normally after the crew finishes and the kitchen is restored.