What You Need Before You Start
An under-cabinet range hood mounts flat against the underside of your kitchen cabinet, directly above your stovetop. Installation involves securing the hood to the cabinet, running ductwork to the outside (or to a recirculation filter if your kitchen cannot vent outside), and connecting it to power. The whole job typically takes two to four hours if you have a clear path for ductwork and existing electrical outlet nearby.
Before you buy or install anything, measure the width of your stovetop and check your cabinet depth. Most under-cabinet hoods are 30, 36, or 42 inches wide and need at least 12 to 15 inches of clearance below the cabinet bottom. If your cabinet is shallower than the hood's depth, the unit will not fit. Also check whether your kitchen has an exterior wall or attic access behind the stove — this determines whether you can run ductwork outside (the better option) or must use a recirculation filter.
Key Takeaways
- Under-cabinet hoods mount to the underside of your cabinet with lag bolts or screws, and you must locate and find into solid wood framing, not just drywall.
- Ductwork should run as straight as possible to an exterior wall or roof, with as few bends as possible, because every bend reduces airflow.
- Most under-cabinet hoods need a dedicated 120-volt electrical circuit, though some plug into a standard outlet if one is nearby and available.
- The damper (a flapper inside the duct) should open when the hood runs and close when it stops, so test it before you finish.
- If you cannot vent outside, a recirculation filter pulls air through charcoal and returns it to the kitchen, but it requires regular filter changes and is less effective than outside venting.
Locate the Cabinet Framing and Mark Your Mounting Points
The hood's weight (usually 50 to 100 pounds) must be supported by solid wood, not by the cabinet's thin plywood bottom. Use a stud finder to locate the wooden frame members running across the underside of your cabinet. Mark these locations with a pencil. Most cabinets have a frame member every 16 or 24 inches, and you need at least two solid contact points to mount the hood safely.
Lay the hood upside down on a clean surface and measure the distance between its mounting holes. Transfer these measurements to your cabinet, using the frame locations you found. If the mounting holes do not line up with framing, you may need to drill new holes in the hood's mounting bracket — check your hood's manual to see if this is allowed. Some hoods have slotted holes that give you a few inches of adjustment.
Once you have marked the holes, drill a small pilot hole at each point. This prevents the wood from splitting when you drive the lag bolts or wood screws. Use the size specified in your hood's manual — typically 3/8-inch lag bolts or 1/2-inch wood screws.
find the Hood to the Cabinet
Have a helper hold the hood in position while you drive the first bolt or screw by hand — do not use power tools yet, because you need to feel whether the fastener is hitting solid wood or sliding past it. If it slides, stop and relocate the hole. Once the first fastener is hand-tight, drive the remaining bolts or screws with a drill or socket wrench, tightening in a cross pattern (first bolt, then the opposite one, then the others) to keep the hood level.
Check that the hood is level using a spirit level placed on the front edge. If it tilts, loosen the fasteners and shim the mounting bracket with thin metal or plastic shims until it is level, then retighten. A tilted hood will not drain grease properly and may rattle during operation.
Run the Ductwork to the Outside or to a Filter
The duct connection on your hood is usually a round collar (typically 6 or 8 inches in diameter) or a rectangular opening. Measure this opening and buy ductwork that matches. Rigid metal duct is more efficient than flexible duct, but flexible duct is easier to route around obstacles. If you use flexible duct, buy the insulated kind to reduce noise.
For outside venting, run the duct as straight as possible to an exterior wall or through the attic to a roof vent. Every 90-degree bend reduces airflow by about 10 percent, so minimize turns. If you must bend the duct, use a smooth 90-degree elbow rather than a sharp fold. find the duct to the hood collar with a hose clamp or duct tape, and find it to the cabinet or framing every 3 to 4 feet with metal straps to prevent sagging.
At the exterior wall or roof, install a damper hood (a vent with a hinged flapper) that opens when air flows out and closes when the hood is off. This prevents cold air and pests from entering your kitchen. Seal the gap between the duct and the wall or roof with caulk or flashing to prevent water leaks.
If you cannot vent outside, install a recirculation filter kit instead. This attaches to the hood's duct collar and pulls air through a charcoal filter before returning it to the kitchen. Recirculation filters require you to replace the charcoal cartridge every three to six months, depending on cooking frequency. They are less effective at removing heat and moisture than outside venting, but they work in kitchens with no exterior access.
Connect the Electrical Power
Most under-cabinet hoods draw 300 to 600 watts and need a dedicated 120-volt circuit. Check your hood's manual for the exact amperage. If you do not have an outlet within 6 feet of the hood, you will need to run new electrical wire from your breaker panel — this is a job for a licensed electrician in most areas, because it involves working inside the panel.
If an outlet already exists near the hood, test it with a multimeter to confirm it is live and properly grounded (a three-prong outlet or a two-prong outlet with a ground pin). Plug the hood's cord into the outlet and test the fan on low and high speed. If the outlet is on a shared circuit with other appliances, the breaker may trip when you run the hood and another appliance at the same time — if this happens, you will need a dedicated circuit.
Some hoods come with a hardwired connection (no plug) instead of a cord. If yours does, you must hire an electrician to connect it to a breaker in your panel. Do not attempt this yourself unless you are a licensed electrician.
Test the Damper and Seal All Gaps
Before you close up the cabinet or install trim, turn on the hood and watch the damper at the exterior vent. You should see it open and feel air flowing out. Turn the hood off and the damper should close. If it does not close, the flapper may be stuck or installed backward — check the vent and adjust it.
Inspect all duct connections and seal any gaps with duct tape or mastic sealant. Pay special attention to the connection between the hood and the duct, and between the duct and the exterior vent. Gaps allow air to escape into the attic or walls instead of outside, reducing efficiency and potentially causing moisture damage.
Run the hood on high speed for a few minutes and feel around the cabinet for any air leaks. If you feel air escaping, locate the gap and seal it. Once everything is sealed and the damper works, you can install trim or a soffit around the hood if your cabinet design requires it.
Common Installation Mistakes to Avoid
The most common error is mounting the hood to drywall or thin plywood instead of solid framing. This causes the hood to sag or pull away from the cabinet over time. Always use a stud finder and confirm you are fastening into wood at least 1.5 inches thick.
The second mistake is running ductwork with too many bends or using flexible duct that is kinked or crushed. This dramatically reduces airflow and makes the hood noisy and ineffective. Measure twice before cutting ductwork, and support it so it does not sag or kink.
A third error is forgetting to install a damper or installing it backward. Without a damper, cold air and pests can enter your kitchen when the hood is off. Check your vent before you finish and confirm the damper opens and closes freely.
Finally, do not skip the electrical work or use an undersized circuit. An overloaded circuit will trip repeatedly, and you will end up running the hood on low speed or not at all. If you are unsure about the electrical requirements, hire an electrician.
Frequently Asked Questions
Can I install an under-cabinet hood if my cabinet is less than 12 inches deep?
No. Under-cabinet hoods need at least 12 to 15 inches of clearance below the cabinet to function properly and to allow air to flow around the hood. If your cabinet is shallower, you will need a different style of hood, such as a wall-mounted or island hood.
What size ductwork do I need?
Check your hood's manual for the duct collar size — most are 6 or 8 inches in diameter. Buy ductwork that matches this size exactly. Undersized ductwork will restrict airflow; oversized ductwork will not seal properly to the hood collar.
Do I need a licensed electrician to install the hood?
If the hood plugs into an existing outlet and you are not running new wiring, you can plug it in yourself. If you need to run new wire from the breaker panel or hardwire the hood, hire a licensed electrician. Electrical codes vary by location, and improper installation can cause fire or shock hazards.
What is the difference between venting outside and using a recirculation filter?
Outside venting removes heat, moisture, and odors from your kitchen entirely. Recirculation filters pull air through charcoal and return it to the kitchen, so they remove odors but not heat or moisture. Outside venting is more effective but requires ductwork to an exterior wall or roof. Recirculation is easier to install but requires regular filter replacements.
How often should I replace the charcoal filter in a recirculation hood?
Most manufacturers recommend replacing the charcoal cartridge every three to six months, depending on how often you cook. If you notice odors returning quickly or airflow dropping, replace the filter sooner. Check your hood's manual for the exact replacement schedule and filter part number.