Restaurant Type-I Hood Grease Duct Cleaning per NFPA 96

Why this matters

A Type-I commercial kitchen exhaust hood collects grease vapor from cooking appliances; the grease condenses on the hood, the duct, and the fan, and accumulates until it ignites. A Type-I hood and its connected duct system is the regulated trade scope for kitchen-exhaust-system cleaning, governed by NFPA 96 and enforced by the local fire marshal, the property's insurance carrier, and the health department. The work overlaps with the chimney sweep's skills (creosote/buildup removal in a vertical flue, draft management, fire prevention) and is the natural commercial diversification for a sweep already comfortable with rooftop work. This SOP is the regulatory and procedural envelope.

Regulatory framework

NFPA 96 Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations is the controlling standard. Adopted by most state and local fire codes by reference. Key sections:

• Chapter 11 covers cleaning frequency.
• Chapter 12 covers cleaning procedure and the post-cleaning inspection report.
• Annex B (informational) covers the cleaning verification protocol.

International Fire Code (IFC) Chapter 6 references NFPA 96 for commercial kitchen ventilation; jurisdictions on the IFC enforce NFPA 96 via the IFC adoption.

State and local mechanical codes may layer additional requirements (typically more frequent cleaning intervals for high-volume operations).

Cleaning frequency

NFPA 96 Table 11.4 sets minimum cleaning frequency by operation type:

• Solid-fuel cooking (wood, charcoal): monthly.
• High-volume cooking (24-hour, charbroiler, wok): quarterly.
• Moderate-volume cooking: semi-annually.
• Low-volume cooking (churches, day camps, senior centers): annually.

The schedule is a floor. If the system is inspected and grease accumulation exceeds NFPA 96 Section 11.6.2 thresholds (0.078 inches measurable grease depth on duct or hood surfaces), the system requires cleaning regardless of the calendar.

Pre-cleaning inspection

Arrive before service: kitchen is shut down, gas appliances are off (verify), pilot lights are off if the cleaning protocol requires (most do not, but solvent-based cleaning may), exhaust fan is off and locked out per OSHA 29 CFR 1910.147 LOTO procedure, fire-suppression system is in the cocked position (do not trip), drain pans are positioned, floor protection is laid.

Measure grease accumulation at the hood, the horizontal duct sections, the riser, and the fan housing. Photo-document baseline.

Cleaning procedure

The NFPA 96 standard requires the entire grease-removal pathway be cleaned to bare metal where accessible. The procedure:

• Hood plenum: remove grease cup, baffle filters, and any removable plenum components; clean to bare metal with caustic detergent (typically alkaline degreaser) or steam, then rinse and dry.
• Horizontal duct sections: access via cleanout doors at every change of direction and at intervals not exceeding 20 feet per NFPA 96 Section 7.3.3; scrape, rod, or pressure-wash to bare metal.
• Vertical riser: rooftop access from above, ground-level access from below, with mechanical brushing or pressure washing through the full length.
• Fan housing: access the fan from above; remove the fan housing cover, scrape grease from the blades and the housing interior to bare metal, verify belt condition, lubricate bearings if access permits.
• Roof: dispose of fan housing cover grease and rooftop drips into containment; do not allow grease into the storm drain.

Where the duct system is inaccessible (insufficient cleanout doors, structural impediments), document the inaccessible area in the cleaning report. NFPA 96 Section 7.3.3 requires the building owner to install additional cleanout doors when access is insufficient; the owner cannot be made compliant by your wishful thinking.

Post-cleaning inspection and report

NFPA 96 Section 11.6.13 requires a written cleaning report that includes the cleaning company, the cleaning technician, the cleaning date, the system components cleaned, the accessibility issues observed (with photos), the components not cleaned (with reasons), and a certification that the system was cleaned to bare metal where accessible.

The report is signed by the cleaning technician and a copy is left on site (the standard is a date sticker affixed to the hood inside the kitchen with the technician name, company name, and the next-due-by date). The original is filed with the building owner; copies typically go to the property manager, the fire marshal, and the insurance carrier.

Technician credentials

NFPA 96 does not federally certify cleaners. The International Kitchen Exhaust Cleaning Association (IKECA) issues the Certified Exhaust System Cleaning Specialist (CESCS) credential. Many insurance carriers and property managers now require IKECA-certified cleaners as a contract condition; some jurisdictions (Massachusetts among them) have state certification programs. Build the credential before competing on the larger property-management contracts.

References

• NFPA 96 Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, current edition.
• International Fire Code (IFC) Chapter 6 Building Services and Systems.
• OSHA 29 CFR 1910.147 Lockout/Tagout.
• IKECA Certified Exhaust System Cleaning Specialist (CESCS) credentialing program.