How to Clean Grease Buildup in Your Range Hood and Ductwork

Grease buildup in your range hood and ductwork is one of those invisible problems that gets worse every time you cook. It starts as a thin film nobody sees, then becomes a sticky, darkened coating that traps heat and reduces airflow. Left untreated, it becomes a fire hazard—grease-laden ducts are how kitchen fires spread through walls and attics. The good news is that tackling it yourself is straightforward work that requires no special skills, just patience and the right degreaser. A properly cleaned hood and duct system will pull smoke and steam efficiently again, keep your kitchen air cleaner, and give you one less thing to worry about during fire season.

1. Kill the Power First. Locate the circuit breaker controlling your range hood and switch it off. If your hood is hardwired, flip the breaker. If it's plug-in, unplug it from the outlet. Wait a full minute to ensure any residual electrical charge dissipates. Do not proceed until you've confirmed the unit is dead—test this by pressing the fan button and confirming nothing happens.
2. Soak While You Work. Open the hood face and locate the mesh or baffle filters. Most hoods have two or three filters that slide or pop out from the frame. Remove them completely and set them in your bathtub or a large plastic storage bin. Fill the bin with hot water—as hot as your tap goes—and add half a cup of liquid degreaser or a degreasing powder. Let the filters soak for at least 20 minutes. The hot water and degreaser will loosen the grease, making scrubbing much easier.
3. Scrub Methodically Both Sides. After soaking, use a soft-bristle brush or an old toothbrush to scrub both sides of each filter. Focus on the mesh openings where grease collects. Work in circular motions and don't press so hard that you bend the mesh. Rinse each filter under running hot water, scrubbing again if necessary. Repeat this cycle until the water running off the filter runs clear. Some heavy buildup may require a second soak.
4. Spray, Sit, Wipe Clean. While filters soak, clean the inside of the hood housing. Mix hot water with liquid degreaser in a spray bottle at a 10-to-1 ratio. Spray the interior surfaces—the underside of the hood, the sides, and the top. Let it sit for three to five minutes, then wipe with a soft cloth or sponge. Pay attention to corners and seams where grease pools. For stubborn buildup, spray again and let it sit longer. Rinse your cloth frequently in clean water and keep wiping until no residue remains.
5. Locate the Grease Layer. Locate where the hood duct connects to the hood itself, usually at the top or back of the unit. You may need to remove a metal collar or unscrew a clamp. Have a flashlight ready and look into the duct opening. You'll likely see a thin to thick layer of grease coating the interior walls. Don't disassemble more than the connection collar—you don't need to disconnect the entire duct run. If your hood vents directly outside through a wall, the connection will be short and accessible.
6. Let Chemistry Do the Work. Fill a spray bottle with the same degreaser-water mixture you used on the hood. Spray into the duct opening, reaching as far as you can see. Work the spray along the visible duct walls. Let the degreaser soak into the grease for five to ten minutes—this is the key step. The degreaser needs time to break down the oils. You may hear or smell it working. Spray again if the first application dries quickly.
7. Rod and Twist Systematically. Wrap a soft cloth around the end of a straightened wire coat hanger, a wooden dowel, or a paint roller extension pole. Secure it with tape so it won't slip. Dampen the cloth slightly with the degreaser solution. Insert the rod into the duct and use it to wipe the interior walls, twisting as you go to reach all angles. Work methodically, pulling back and pushing forward to cover the full depth of the accessible duct. Keep replacing the cloth with fresh, damp ones as they become dark with grease. You won't reach the entire duct run, but you can access the first 18 to 24 inches, which is where most grease accumulates.
8. Seat Filters Precisely. Remove the filters from the soapy water and shake off excess water. Stand them upright to drain. Pat them dry with a clean towel and let them air-dry for 15 minutes. Once they're dry, slide or pop them back into the hood frame, ensuring they seat properly and align with any guide rails. Close the hood face.
9. Seal the Connection Tight. Before reconnecting the duct, wipe the inside of the metal collar with a damp cloth and degreaser to remove any grease residue. Dry it thoroughly. Reattach the collar to the hood, tightening any clamps or fasteners. Make sure the connection is snug and there are no gaps. A loose connection reduces suction and allows cooking odors to escape into the wall cavity.
10. Restore the Shine. Use the same degreaser spray on the outside of the hood—the top, front, and sides. Many hoods have a stainless steel or painted finish that collects cooking residue and fingerprints. Spray lightly, let sit for a minute, and wipe with a soft cloth. For stainless steel, wipe in the direction of the grain. Dry completely to prevent water spots.
11. Confirm Suction Returns. Return to your breaker panel and switch the hood circuit back on. Go to the kitchen and press the fan button on your hood. Listen for smooth, strong suction sound. The airflow should feel noticeably stronger than before, and cooking odors should be pulled up and out. Run the fan for two to three minutes to clear any dust or degreaser fumes from the ductwork.