Kitchen Exhaust Cleaning Guide

The system, part by part

A commercial kitchen exhaust system is one continuous path. Grease-laden vapour rises off the cooking surface, gets captured by the hood, passes through baffle filters, travels through duct work and is discharged by the exhaust fan. Every component collects residue, and the components you cannot see collect the residue that matters most.

Hood canopy and plenum

The visible capture area plus the chamber behind the filters. Kitchen staff can keep the exterior presentable; the plenum needs professional degreasing.

Baffle filters

Designed to force vapour to change direction so grease condenses and drains. They are the system's first defence and the only part most kitchens maintain themselves.

Duct work

Horizontal runs and vertical risers between hood and fan. This is where deposits build unseen, and where a cleaning is most often skipped because access panels are missing or painted shut.

Exhaust fan

Usually rooftop, sometimes inline. The housing, blades, hinge and curb collect grease that both unbalances the fan and stains or damages the roof.

What a complete cleaning involves

1. Inspection. Walk the system, find access points, note the accumulation level and identify any sections that cannot be reached.
2. Protection. Cover cooking equipment, prep surfaces and floors before anything is opened.
3. Filter service. Remove and degrease filters; flag any that are damaged or warped enough to need replacement.
4. Hood and plenum. Degrease the canopy interior and the chamber behind the filters down to bare metal where achievable.
5. Duct runs. Open access panels and clean accessible horizontal and vertical sections, containing runoff throughout.
6. Fan. Tilt or open the housing, clean blades and interior, and clear the curb area on the roof.
7. Reassembly and cleanup. Refit filters and panels, confirm the fan runs correctly, and leave the kitchen ready for service.
8. Documentation. A written record of areas cleaned, areas not accessible, and recommendations — including any access panels the system needs.

How to spot a partial job

• The crew never went on the roof, yet the invoice says the system was cleaned
• No access panels were opened anywhere along the duct
• The visit took under an hour on a heavily loaded system
• There is no written record of what was and was not reached
• The quote said "hood cleaning" and nobody defined where it stopped

If duct and fan are not in writing, assume they are not in the price. See what drives cost for how scope and price relate.

Why the hidden sections matter most

Grease in duct work is the part of the system nobody sees and the part that carries the most risk. It also restricts airflow, which makes the kitchen hotter, pushes smoke back onto the line and forces the fan to work harder than it was specified to. Cleaning only what is visible fixes appearance and nothing else.