It's the question every kitchen manager eventually asks, usually right before an inspection. The honest answer: it depends on what and how much you're cooking - but NFPA 96 gives a clear framework rather than a guess.

The four frequency categories

• Monthly - solid-fuel cooking (wood, charcoal) or very-high-volume operations

• Quarterly - high-volume cooking such as charbroiling, wok stations, or 24-hour kitchens

• Semi-annually - moderate-volume restaurants, the most common category for standard full-service kitchens

• Annually - low-volume or seasonal operations, like churches or day camps

One detail that catches kitchens off guard: if you run multiple types of cooking equipment, your entire exhaust system follows the frequency required by your highest-risk equipment. Add a charbroiler to a kitchen that previously only needed semi-annual cleaning, and the whole system moves to a quarterly schedule.

If you're not sure which category your kitchen falls into, a compliance inspection is the fastest way to find out - and it gives you documentation either way.

NFPA 96 is the standard fire and health authorities in BC lean on when they evaluate a commercial kitchen's exhaust system. Most local jurisdictions fold it directly into their fire code, which means it's not optional guidance - it's enforceable.

What it actually requires

At a practical level, NFPA 96 expects three things from your kitchen: your exhaust system stays clean on a schedule matched to your cooking volume, the work is done by trained and qualified people rather than general cleaning staff, and you keep records of every cleaning - dates, scope, and what was done.

Grease buildup in the exhaust system is one of the most common causes of commercial kitchen fires, which is exactly why cleaning frequency and documentation get so much attention from inspectors. A kitchen that's overdue for cleaning - even by a few weeks - is often the first thing flagged in a fire inspection.

What to keep on hand

At minimum: your last cleaning date, a copy of the service report, and before/after documentation if your provider offers it. That's usually enough to satisfy a fire marshal or insurance review on the spot.

Most kitchens find out their exhaust system is overdue the hard way - at an inspection, or worse. These signs usually show up first.

• Visible grease on the hood exterior or around filters - if you can see it on the surface, there's more built up inside.

• Weaker airflow or a hotter kitchen than usual - grease-clogged filters and ducts restrict the system's ability to pull smoke and heat out.

• Persistent odors that cleaning the kitchen doesn't fix - often a sign grease has accumulated somewhere the daily clean doesn't reach.

• It's been longer than your last documented interval - if you can't remember your last professional cleaning, you're likely overdue.

• New equipment or a menu change added higher-heat cooking - adding a charbroiler or wok station can shift your required cleaning frequency entirely.

None of these are things to wait out. Grease is a fire risk that gets worse, not better, with time.

If you've never had a professional crew in for a hood cleaning, knowing what the visit actually looks like makes it easier to prepare - and to know what a thorough job should include.

Before the crew arrives

Clear counters and equipment near the hood where possible, and confirm access to the roof if your fan requires it. We'll confirm timing in advance so it fits your service hours.

During the service

The crew protects surrounding surfaces and equipment first, then works through the hood canopy, filters, accessible ductwork, and fan components in sequence - degreasing to bare metal where accessible. A final check confirms nothing was missed before filters go back in.

After the service

You'll receive a written record of what was cleaned, photo documentation, and a recommended date for your next service based on your cooking volume. 

Keep this on file - it's what you'll hand over at your next inspection.