What You Need Before You Start

A ducted range hood pulls cooking smoke and steam out of your kitchen through ductwork that vents to the outside of your home. Installation requires running that duct from the hood to an exterior wall or roof, which is more involved than plugging in a recirculating model, but it removes odors and moisture far more effectively. You can install one yourself if you are comfortable with basic carpentry and drilling, though some jurisdictions require a licensed electrician to handle the wiring.

Before you buy or start work, measure the space above your stove and confirm you have a clear path to an exterior wall or roof. Check your local building codes—some areas require permits for range hood installation, and a few mandate professional installation. If you are renting, ask your landlord before making any holes in walls or ceilings.

Key Takeaways

  • Ducted range hoods require a clear path from the hood to outside your home, either through a wall or roof, and you must turn off power at the breaker before touching any electrical connections.
  • The duct should slope slightly downward toward the outside to prevent condensation from running back into the hood, and you should use the shortest, straightest duct run possible to maintain suction.
  • Most hoods mount to the wall studs or cabinet above the stove using lag bolts or screws, and the mounting height is typically 28 to 36 inches above the cooking surface.
  • Sealing all duct joints with mastic sealant or foil tape prevents air leaks that reduce suction and waste energy, and a damper flap on the exterior vent prevents outside air from flowing back in.
  • Electrical connections must be made inside a junction box, and if you are not confident wiring a 240-volt hood, hire a licensed electrician rather than guessing.

Measure and Plan Your Duct Route

The duct path determines whether installation is straightforward or complicated. Open your cabinets and look directly above the stove to see what is there—if you have a soffit (a dropped ceiling), you may be able to run the duct through it. If you have open space to the roof, that is simpler. If you need to go through a wall, identify which exterior wall is closest and check whether it faces a patio, driveway, or a neighbor's window (venting directly at someone's face is poor form and may violate local codes).

Measure the distance from the hood to the outside vent opening. Ductwork loses efficiency with every bend and every foot of length, so aim for the shortest, straightest path you can manage. A 6-inch-diameter duct is standard for most residential hoods. If your duct run is longer than 10 feet or requires more than two 90-degree bends, you may need to upgrade to an 8-inch duct or a more powerful motor to maintain suction.

Check what is behind the wall or ceiling you plan to cut into. Use a stud finder to locate framing, and if you are going through a wall, drill a small pilot hole from inside to outside so you can see where the opening will be. Look for electrical wiring, plumbing, or gas lines before you cut. If you hit any of these, stop and reroute your duct path.

Mount the Range Hood to the Wall or Cabinet

Most ducted range hoods mount to the wall studs above the stove. The standard height is 28 to 36 inches from the cooking surface to the bottom of the hood—check your hood's manual for the manufacturer's recommendation, as some models have specific requirements. Use a level to mark a horizontal line at the correct height, then locate the wall studs using a stud finder and mark them lightly with pencil.

Hold the hood up to the wall and align the mounting holes with the studs. If the holes do not line up with studs, you have two options: drill new holes in the hood's mounting bracket (if the bracket allows it) or use heavy-duty toggle bolts rated for the hood's weight. Most hoods weigh 50 to 100 pounds, so do not skimp on fasteners. Use lag bolts or wood screws at least 2.5 inches long, driven into the studs. Tighten all bolts evenly so the hood sits level.

If you are mounting to a cabinet instead of a wall, follow the same process but use the cabinet's internal framing. Some under-cabinet hoods have a template that shows exactly where to drill—use it. Pre-drill all holes slightly smaller than your fastener diameter to prevent splitting the wood.

Cut the Duct Opening and Install Ductwork

Once the hood is mounted, you need to cut an opening for the duct to exit. If you are venting through the roof, you will need to go up into the attic and cut from above. If you are venting through a wall, you can cut from inside the kitchen. Mark the center point of your duct opening on the wall or ceiling, then use a drywall saw or hole saw to cut a hole slightly larger than your duct diameter—typically 6.5 inches for a 6-inch duct, to account for the duct wall thickness.

Slide the duct connector (the part that attaches to the hood) onto the duct collar and find it with three sheet metal screws. Do not use duct tape alone—it fails over time. Run the duct through the wall or ceiling opening and toward the exterior. The duct should slope slightly downward as it goes outside, at least a quarter inch per foot of run. This slope prevents condensation from pooling inside the duct and dripping back into the hood.

Use elbows and straight duct sections to navigate around obstacles. Minimize bends—each 90-degree bend reduces airflow. When you reach the exterior wall or roof, install a wall cap or roof flange with a damper flap. The damper flap is a one-way door that lets air out but prevents outside air, rain, and pests from coming back in. find the flange with the fasteners specified by the manufacturer, usually lag bolts or roofing nails, and seal around it with roofing cement or caulk rated for your climate.

Seal All Duct Joints

Unsealed duct joints leak air, which reduces suction and wastes energy. Do not rely on duct tape—it dries out and peels away within a few years. Instead, use mastic sealant, a putty-like compound that stays flexible and lasts the life of the duct. explore mastic to every joint where two duct sections meet, and wrap the joint with foil-backed duct tape for reinforcement. Smooth the mastic with a putty knife so it fills all gaps.

Pay special attention to the connection between the hood and the duct, and between the duct and the wall or roof opening. These joints see the most movement and temperature change, so seal them thoroughly. If you are using flexible duct (which is easier to route around obstacles), make sure it is fully extended and not kinked or compressed, as kinks reduce airflow significantly.

Connect the Electrical Supply

Before you touch any wires, turn off power to the circuit at the breaker panel. Most ducted range hoods run on either 120 volts (standard household current) or 240 volts (higher power, for more powerful motors). Check your hood's manual to see which voltage it requires and whether it needs a dedicated circuit.

The hood must connect to power through a junction box—a metal or plastic box that houses the electrical connections and keeps them safe. If your hood does not come with a junction box, you must install one. Run electrical cable from the breaker panel to the junction box, then from the junction box to the hood's terminal block. All connections must be made with wire nuts or terminal blocks rated for the wire gauge and voltage you are using.

If your hood requires 240 volts and you are not confident wiring a high-voltage circuit, hire a licensed electrician. Mistakes with 240-volt wiring can cause fires. Once the connections are made, turn the breaker back on and test the hood at low and high speed to confirm it runs and the damper flap opens when the motor starts.

Test Airflow and Adjust as Needed

Turn on the hood at high speed and hold a piece of tissue paper near the cooking surface. The tissue should be pulled upward toward the hood. If it is not, check for blockages in the duct or damper flap. Go outside and confirm that air is coming out of the exterior vent and that the damper flap is opening. If the damper is stuck, clean it or replace it.

If airflow is weak despite a clear duct, you may have too many bends or too long a duct run for the hood's motor. Some hoods have a damper adjustment screw inside the duct collar—check your manual. If the hood is still weak, you may need to upgrade to a more powerful model or simplify the duct route.

Listen for rattling or vibration. A small amount of vibration is normal, but excessive noise usually means the duct is touching a stud or joist. Wrap the duct with foam insulation or rubber hangers to isolate it from the framing. Once everything is running smoothly, install the filter or grease trap according to the hood's manual, and you are done.

Frequently Asked Questions

Can I use flexible duct instead of rigid duct?

Yes, flexible duct is easier to route around obstacles and is fine for most installations. However, it reduces airflow more than rigid duct, so keep the run as short as possible and make sure it is fully extended, not kinked or coiled. Rigid duct is more efficient if you have a long run or a weak motor.

What if I cannot vent through an exterior wall or the roof?

You cannot vent a ducted hood into your attic or basement—the moisture and heat will damage insulation and framing. If an exterior vent is not possible, you need a recirculating hood instead, which filters the air and returns it to the kitchen. Recirculating hoods do not remove moisture as effectively, but they are the only option if ducting outside is not feasible.

Do I need a permit to install a range hood?

Permit requirements vary by location. Some jurisdictions require a permit for any work involving ductwork or electrical connections, while others do not. Call your local building department and ask—it is better to know before you start. If a permit is required and you skip it, you may have trouble selling your home later.

How often should I clean the duct?

Grease builds up inside the duct over time, especially if you cook frequently. Clean the duct at least once a year by removing the duct sections and wiping them out with a cloth. For a long duct run, you may want to hire a professional duct cleaning service every few years.

What if the damper flap gets stuck?

A stuck damper usually means grease or debris has accumulated inside. Go outside and inspect the flap—if it is clogged, clean it with a cloth and degreaser. If it is damaged or will not move freely after cleaning, replace it. A stuck damper reduces airflow and allows outside air to enter the kitchen when the hood is off.