How To Install a Kitchen Hood Roof Vent

Plan your route from the kitchen to the attic

Whichever route you choose, ensure the total duct length doesn’t exceed the fan capacity. The owner’s manual usually tells you specifics on duct sizes and lengths.

• Determine where you will install the range hood, then mark where the ductwork will meet the range hood on the wall.
• Chuck an 18-inch section of straightened coat hanger into a drill.
• Loosely hold the wire and direct it through the ceiling drywall approximately where your vent pipe will go.
• Go up in the attic, find the coat hanger and push the insulation aside to ensure there are no joists, electrical wiring or other building materials that might block a 6-in. hole.
• If you hit a joist or other obstruction, move your point of entry until the wire passes through easily.

Install ductwork in the kitchen

• Back in the kitchen, mark the cabinets and cut holes for the ducts.
• Center a piece of ductwork over the original mark on the ceiling made by the straightened wire.
• Use a pencil to trace the ductwork.
• Use a drywall saw to cut and remove the drywall.
• From the mark where it will connect with the hood, run the ductwork up into the attic.
• Use 1/4-in. sheet metal screws to secure, then wrap each joint with aluminum-faced duct tape.

Plan your route from the attic to the roof

Ensure your intended roof exit is 12 to 18 inches from any other vents on the roof, Feller recommends.

• Still in the attic, examine the roof directly above the installed ductwork to ensure there’s room to install a roof vent.
• Drop a plumb bob down from the roof to the duct and find the approximate roof exit location. You may have to shift the vent position several inches to avoid ceiling and roof framing.
• Drill a screw through the roof to mark the exit location.

Cut away shingles to make room for the roof cap

This part of the project is done on the roof. Use a safety harness system and work on a dry day. “If the roof is not a shingle roof, I would strongly recommend hiring a roofing professional,” Feller says.

• On the roof, locate the protruding screw from the attic.
• Measure the roof cap (not including the flange). Add an inch on both sides, then transfer that measurement to the shingles using the screw as a center point. “The shingles need an approximate 1-inch clearance to allow the water to flow freely around and down the roof,” Feller says.
• Use a roofing crowbar to lift the shingles on the top half of the marked area. Leave the bottom half intact for now.
• Cut away the top row of shingles along the marked lines using tin snips. Then use a utility knife the remove any remaining shingle courses and roofing paper on the top half only.
• On the bottom portion of the marked area, cut away the top layer of shingles. Leave a single layer as the roof cap will sit on top.

Cut the hole for ductwork in the roof

Once the shingles are removed to make way for the roof cap, cut the hole for the ductwork.

• “Take the vent pipe or a piece of it, and draw a circle on the roof to get your hole size,” Feller says. Consider extending the circumference by a 1/4-inch for extra room.
• Use a drill with a spade bit to create a starter hole through the roof.
• Cut away any remaining shingle and paper within the traced circle using a utility knife.
• Use a reciprocating saw to cut through the sheathing along the traced line.

Dry fit the roof cap

The roof cap will slide under the top half of the shingles and will sit on top of the bottom row of shingles.

• Use a pry bar to lift the shingles along the top and sides where the roof cap will be installed. This makes room for the flange to slide under the shingles.
• Remove any roofing nails you encounter with the pry bar.
• Slide the roof cap under the shingles into place over the circle opening. Ensure the top part of the flange goes underneath all layers of shingles.
• Check to make sure the placement is correct then remove the roof cap.

Finish the roof cap

• Flip the roof cap over and lay a thick bead of roof sealant along the top and sides of the roof cap flange. Skip the bottom portion to allow for drainage.
• Re-install the roof cap under the top shingles and over the bottom shingles.
• Secure the exposed bottom cap flange with roofing nails.
• Lift the shingles and add nails on the top and sides of the flange. Work carefully to not damage any shingles.
• Next, lift the shingles again and run a bead of sealant along the top and sides of the flange edge.
• Glue down any pried up shingles with roof sealant.
• “If you put any nails through the bottom apron of the flashing, and they are exposed, be sure to cover them with sealant to prevent oxidation or rust,” Feller says.

Connect ductwork to roof vent

Go back into the attic to connect the ductwork to the roof vent.

• Use 1/4-in. sheet metal screws and aluminum-backed duct tape to secure rigid ductwork to the roof vent insert.
• If you live in an area where frost occurs, add an insulated duct sleeve to the portion of pipe in the attic.

Family Handyman

Install the hood

Finally, install the range hood. Installation will vary based on your hood make and model, so follow the manufacturer’s instructions for specific details.

• Attach the transition duct to the hood and make sure the damper flap operates freely.
• Secure any necessary electrical connections.
• Lift the hood into place and attach it to the wall.
• Connect the ductwork to the transition duct with 1/4-in. sheet metal screws, then wrap the joint with aluminum-backed duct tape.
• Caulk around the vent pipe where it enters the ceiling with silicone.

Agrima Sharma/Family Handyman

Frequently Asked Questions

How does a kitchen vent differ from a bathroom vent?

A kitchen vent is typically more powerful than a bathroom vent.

Does a kitchen vent need to be vented outside?

No, a kitchen vent doesn’t need to be vented outside. Recirculation, or ductless vents filter, then reintroduce air into a kitchen and do not need to be vented outside. An exception would be a commercial gas range.

Do you need a kitchen vent?

While there is no national code for venting gas appliances, some states and municipalities do require kitchen vents, especially over a gas appliance. Hogan recommends adding a range hood during a kitchen remodel, even with an electric stove. “Vent it to the outside in case you get a gas stove in the future,” he says.

What if I can’t vent my kitchen through the roof?

If you can’t vent your kitchen through the roof, “you can always go through a roof gable wall instead,” Hogan says. Or you can use a recirculation vent that does not require ductwork.

Do ductless exhaust fans work?

Ductless exhaust fans can be used to vent a kitchen range, “but it’s always best to vent to the exterior if you can,” Hogan says.

About the Experts

• Ami Feller is the founder and owner of Roofer Chicks, a full-service roofing company based in New Braunfels, Texas, and one of the only all-female roofing crews in the United States. In addition, Ami sits on the board for Habitat for Humanity, has been featured in many publications and articles and is a trusted expert in her industry.
• Liam Hogan is the owner of Hogan Mechanical Incorporated a full-service residential and commercial plumbing and HVAC company in Springfield, Massachusetts. He has ten years of industry experience.