Grease Dripping From Range Hood? 7 Causes and How to Stop It

Grease dripping from a range hood is almost always a capacity problem: the filters, grease cup or duct are holding more grease than they can keep, and the excess runs back down onto your cooktop. Clean the filters and empty any grease cup first. If drips come back within a week or two, the grease is coming from the duct, and the checks further down will find where.

If grease is burning on the cooktop: turn off the heat and smother small flames with a lid. Never use water on a grease fire. Baking soda or a Class K or Class B extinguisher works on a small fire; if it spreads, get out and call 911.

Quick diagnosis

1. Saturated grease filters

Metal filters trap grease by making it condense on the mesh or baffles. Once they’re coated, new grease has nowhere to stick, so it runs to the lowest edge and drips.

How to check

1. Turn off the hood and cooktop and let everything cool.
2. Remove the filters. If they feel sticky all over, drip when you tilt them, or you can’t see light through the mesh, they’re saturated.

How to fix

1. Wash metal mesh or stainless baffle filters in hot water with degreasing dish soap and about ½ cup of baking soda, soaking for 15–20 minutes and scrubbing with a soft brush. Our filter cleaning guide covers the details, including dishwasher tips.
2. Replace filters that are torn, warped or that stay tacky after two cleanings.
3. Set a schedule: every month with heavy or frying use, every 1–3 months otherwise.

Check the filter orientation

Baffle filters and some mesh filters are designed to go in one way, so grease drains toward a channel or cup. Installed backwards, they drain toward the front edge and drip onto the cooktop.

1. Look for an arrow, “front,” or “this side down” marking on the filter frame.
2. If there’s no marking, check the manual. Baffles usually slope so grease runs toward the back or sides of the hood.

2. Full grease cup, tray or channel

Many wall and island hoods have a grease channel around the filters that drains into a small removable cup, often at the back or sides. When it fills, it overflows.

How to check

1. Look for a small cup, a clip-on tray or a trough along the filter frame.
2. Check whether it’s full or whether its drain hole is clogged with hardened grease.

How to fix

1. Remove and empty the cup into the trash, not the sink drain.
2. Wash it in hot soapy water. Clear the drain hole with a toothpick or pipe cleaner.
3. Check it every time you clean the filters.

3. Condensation running back from the duct

If the drips are thin, brownish and worse in cold weather, you’re probably looking at water, not pure grease. Warm, humid cooking air cools as it travels through a duct in a cold attic or exterior wall, condenses, picks up grease on the way, and runs back into the hood.

How to check

1. Touch a drip with a paper towel. A watery spot that spreads quickly suggests condensation; a translucent, oily spot is grease.
2. Notice when it happens. Drips during or right after cooking in cold months point to condensation.
3. Find out where the duct runs. Uninsulated duct through an unheated attic is the classic setup.

How to fix

1. Run the hood 5 minutes before cooking and 10–15 minutes after, so the duct warms up and dries out.
2. Insulate duct runs through unheated spaces. Rigid metal duct can be wrapped with foil-faced insulation.
3. Make sure the exterior damper closes fully, so cold air doesn’t sit in the duct between uses.

Our guide to range hood condensation and water drips goes deeper on insulation and duct routing.

4. Duct sloped back toward the hood

Horizontal duct runs should pitch slightly toward the outside, so any liquid that forms drains out rather than back into the hood. A run that sags or slopes toward the hood collects grease and water and sends it back to you.

How to check

1. In an attic or basement, set a level on horizontal sections of the duct.
2. Look for low spots where sections sag between hangers.

How to fix

1. Re-hang the duct so it falls gently toward the exterior cap. Many installers use a slope of about ¼ inch per foot.
2. Add hangers or straps to remove sags.
3. If the duct is inside a finished ceiling, this is a job for a contractor.

5. Leaky duct seams and protruding screws

Grease that condenses inside the duct can seep out of unsealed joints and run down the outside of the duct into the hood or cabinet.

How to check

1. Turn off power at the breaker, not only at the hood’s switch.
2. Remove the filters and look at the collar and first duct joint with a flashlight. Grease stains or streaks on the outside of the duct show leaks.
3. Look for screw tips poking into the duct. They catch grease and lint and start buildup.

How to fix

1. Clean the joint with degreaser and let it dry fully.
2. Seal it with foil tape. Cloth duct tape fails with heat and grease.
3. Replace screws that stick into the airflow with shorter ones, or fasten the joint from outside with foil tape and metal straps.

6. Grease sticking to the hood instead of going into it

If you find a sticky film on the underside and inside walls of the hood that drips when it warms, the hood isn’t capturing grease efficiently, so it settles on the nearest cool surface.

How to check

1. Look at when you turn the hood on and which speed you use for frying and searing.
2. Measure the height from cooktop to hood bottom. Typical ranges are 24–30” over electric and 30–36” over gas; your manual governs.
3. Check the hood’s CFM against your cooktop. Our CFM calculator gives a quick estimate.

How to fix

1. Use high speed whenever you fry or sear, and start the hood before the oil heats.
2. Use back burners for greasy cooking.
3. Clean the underside and interior with a degreaser. For hardened, sticky layers, see removing baked-on grease from a range hood.

7. Grease built up in the duct or blower

If you clean the filters and cup and drips still come back within days, grease has probably collected past the filters, in the blower housing or the duct itself. This is common when a hood was run without filters or with torn ones for a while.

How to check

1. Turn off power at the breaker, not only at the hood’s switch.
2. Remove the filters and blower cover (if your manual allows it) and look at the blower wheel and housing.
3. Shine a flashlight up the duct. A shiny, sticky coating or visible grease clumps mean buildup.

How to fix

1. Wipe the blower housing and wheel with degreaser if they’re accessible and the manual says they’re user-serviceable.
2. Don’t try to scrape the inside of a long duct run yourself. Read about the fire risk and cleaning options in grease in ductwork.

When to call a pro

Call an HVAC contractor, appliance technician or duct cleaning service when:

• You can see thick grease deposits inside the duct or blower housing. That’s a fire risk.
• The duct runs through a finished ceiling, wall or roof and needs to be re-sloped, insulated or resealed.
• Grease has dripped onto wiring, the motor or the light sockets.
• The hood has had a grease fire, even a small one. Have it and the duct inspected before using it again.

The bottom line

Clean the filters, check their orientation, and empty the grease cup. That stops most drips the same day. If drips return quickly or look watery, look up the duct: condensation, bad slope, leaky seams or buildup are the causes, and fixing them keeps grease where it belongs.