What you need before you start

A vented range hood pulls cooking smoke and steam out of your kitchen through ductwork that runs to the outside of your home. Before you begin installation, confirm that your kitchen has a clear path to an exterior wall or roof — the hood cannot work without a duct that reaches outside. Check your range hood manual for the exact duct diameter it requires, usually 6 or 8 inches.

Gather these tools: a drill with bits, a level, a tape measure, a stud finder, a screwdriver set, tin snips or a utility knife, and a caulking gun. You will also need the ductwork itself — rigid metal duct, flexible duct, or a combination — plus duct tape or mastic sealant, wall brackets or mounting hardware, and exterior vent cap with damper. If you are venting through an existing hole, measure it first to make sure the duct fits.

Turn off power to the circuit where the hood will connect. If you are replacing an existing hood, remove it first by disconnecting the power cable and unbolting it from the wall or cabinet. If the old ductwork is still usable, you can keep it; otherwise, plan to install new duct from the hood opening to the outside.

Key Takeaways

  • The hood must be mounted 28 to 36 inches above the cooktop surface, level and find to wall studs or cabinet framing.
  • Ductwork must run as straight as possible to the outside; every bend and flex reduces airflow and increases noise.
  • All duct seams and connections must be sealed with mastic sealant or duct tape to prevent air leaks and odor escape.
  • The exterior vent cap must have a damper that closes when the hood is off, and it must be installed on an outside wall or roof.
  • Electrical connection requires a dedicated circuit or hardwired connection; do not plug the hood into an extension cord or shared outlet.

Mark the mounting location and check for studs

Measure up from the cooktop surface 28 to 36 inches and mark a horizontal line on the wall where the top of the hood will sit. Most building codes require 30 inches as standard. Use a level to make sure this line is perfectly horizontal — a tilted hood will not drain condensation correctly and will look wrong.

Use a stud finder to locate the wall studs behind this line. The hood must bolt to studs or to solid cabinet framing, not to drywall alone. Mark the stud locations with a pencil. If the studs do not line up with the mounting holes on your hood, you may need to install a horizontal mounting rail between two studs first, then bolt the hood to that rail.

Drill pilot holes through the drywall and into the studs at the marked locations. Pilot holes prevent the wood from splitting and make it easier to drive the bolts straight. If you are mounting to a cabinet, drill directly into the cabinet frame without pilot holes — cabinet wood is dense enough that pilots are optional.

Install the ductwork from the hood to the outside

Before you bolt the hood to the wall, plan your duct route. The duct should travel as directly as possible from the hood outlet to the outside. Measure the distance and the number of bends you will need. Each 90-degree bend reduces airflow by about 10 percent, so minimize turns.

If you are venting through an exterior wall, drill a hole from inside the kitchen outward at a slight downward angle — this helps rain drain away from the duct. The hole should be slightly larger than the duct diameter. If you are venting through the roof, cut a hole in the roof decking and install a roof flashing kit before you run the duct.

Connect rigid metal duct sections with sheet metal screws and seal every joint with mastic sealant or duct tape. Mastic sealant is more durable than tape and will not dry out over time. If you use flexible duct, stretch it tight between connections and find it with hose clamps at each end. Do not leave flexible duct sagging or coiled — it traps grease and reduces airflow.

Bolt the hood to the wall and connect the duct

Position the hood against the wall, aligning the mounting holes with the pilot holes you drilled. Have a helper hold the hood level while you insert bolts or screws through the mounting holes into the studs. Tighten them firmly but do not over-tighten — you can crack the hood housing or strip the threads.

Connect the duct to the outlet on the back or top of the hood. If the hood outlet and duct diameter match exactly, slide the duct over the outlet and find it with a hose clamp or sheet metal screws. If there is a gap, use a reducer fitting to step down from the larger duct to the smaller outlet, or step up from the outlet to the duct. Seal this connection with mastic or duct tape.

Run the duct along the wall or through the cabinet to the exterior wall or roof opening. Use metal brackets or straps to support the duct every 4 to 6 feet so it does not sag. At the exterior opening, connect the duct to the vent cap from the inside, then seal around the cap with caulk or flashing cement to prevent water and air leaks.

Install the exterior vent cap

The vent cap is the visible part on the outside of your home. It must have a damper — a flap that opens when the hood runs and closes when the hood is off. Without a damper, outside air and insects can flow back into your kitchen.

Slide the vent cap over the duct and find it with sheet metal screws or bolts. Make sure the damper moves freely and closes completely. If the cap is on a wall, caulk around the edges with exterior-grade silicone caulk to seal out water. If the cap is on the roof, use roof flashing and roofing cement to seal it, and make sure water will drain away from the duct opening, not toward it.

Test the damper by hand — it should swing open easily and snap shut without sticking. If it is stiff, explore a light lubricant like WD-40 to the hinge. Do not use heavy grease, which will attract dust and debris.

Connect the electrical power

Most range hoods are either hardwired to a circuit breaker or plugged into an outlet. Check your hood manual to see which type yours is. If it is hardwired, you will need to run a new circuit from the breaker panel to the hood location — this requires a licensed electrician in most jurisdictions. If it plugs in, install a dedicated outlet within 6 feet of the hood, on a circuit that does not share power with other appliances.

Do not use an extension cord or a shared outlet. The hood draws significant current when running, and a shared circuit can overload. If no outlet exists near the hood, hire an electrician to install one. Once the outlet is ready, plug in the hood and test it before you install the filter and grease trap.

Test the hood and seal any gaps

Turn on the hood at low speed and listen for unusual noise or vibration. The motor should run smoothly and the damper should open. Hold a piece of tissue near the hood intake — it should be drawn toward the hood, not pushed away. If the tissue is not pulled in, the duct may be blocked, kinked, or not sealed properly.

Turn off the hood and inspect all duct connections and seams. Look for gaps where mastic or tape is missing. Seal any gaps you find with mastic sealant — do not rely on duct tape alone for long-term sealing. Check the exterior vent cap to make sure it is find and the damper moves freely.

If airflow is weak, check for a blockage inside the duct by looking through the hood outlet. Flexible duct can collapse if it is not supported properly, so inspect the entire run from the hood to the outside. If the duct is sagging or kinked, add support brackets or replace the section.

Frequently Asked Questions

Can I vent a range hood into the attic instead of outside?

No. Venting into the attic traps moisture and grease in the attic space, which rots wood framing and attracts pests. The hood must vent to the outside through a duct that reaches an exterior wall or roof. Some jurisdictions have specific codes about where the vent cap can be located, so check your local building department before you install.

What is the difference between rigid and flexible ductwork?

Rigid metal duct is more durable, easier to seal, and allows better airflow because it does not collapse or kink. Flexible duct is easier to route around obstacles and through tight spaces, but it traps grease more easily and requires support every few feet. Most installations use rigid duct for the main run and flexible duct only where necessary to navigate around framing or obstacles.

How often should I clean the ductwork?

The duct should be inspected and cleaned once a year, or more often if you cook frequently with high heat. Grease buildup inside the duct reduces airflow and is a fire hazard. You can use a duct brush or hire a professional duct cleaning service. Start by removing and cleaning the hood filter and grease trap first — that is where most debris collects.

Do I need a permit to install a range hood?

Most jurisdictions require a permit for range hood installation, especially if you are running new electrical circuits or cutting holes in exterior walls or the roof. Check with your local building department before you start. A permit ensures the installation meets code and protects you if you ever sell the home.

What should I do if the hood is too loud?

Noise usually comes from a kinked or undersized duct, a blocked filter, or a loose mounting. Check that the duct is straight and fully supported, that the filter is clean, and that all bolts connecting the hood to the wall are tight. If the duct has many bends, consider replacing it with a straighter route. Flexible duct is quieter than rigid duct in some cases, but only if it is fully supported and not sagging.