What You Need Before You Start
A range hood vent installation requires three things: the right tools, a clear path from your cooktop to the outside, and a few hours of work. Most installations fall into one of two categories — venting through an exterior wall or through the roof — and the path you choose determines what materials you buy and how much cutting you do.
Before you buy anything, measure the distance from your cooktop to the nearest exterior wall or roof opening. Check whether your kitchen has existing ductwork you can reuse; if there is old ductwork in place, you may be able to disconnect it and run new ducting through the same path. If you are starting from scratch, you will need to cut a hole through drywall, siding, or roofing, so confirm you have access and that no plumbing, electrical wiring, or structural beams are in the way.
Gather these tools before you begin: a drill with bits, a drywall saw or reciprocating saw, a level, a tape measure, a screwdriver (usually Phillips head), ductwork (typically 6-inch diameter rigid or flexible aluminum), duct clamps, exterior wall cap or roof flashing, caulk, and a stud finder. Read your hood's manual first — some models have specific mounting requirements or electrical connections that differ from standard installations.
Key Takeaways
- Range hood vents must run to the outside of your home, either through a wall or roof, and cannot safely vent into your attic or crawlspace.
- The most common installation path is through an exterior wall, which requires cutting a hole, running ductwork, and sealing the opening with a wall cap.
- Roof vents are more complex because they require flashing to prevent water leaks, but they work well if your hood is directly below the roof line.
- Flexible ductwork is easier to route around obstacles but traps grease more readily than rigid duct, so clean it more often.
- Most installations take three to five hours and do not require a licensed electrician unless you are hardwiring the hood to a circuit breaker.
Mounting the Hood and Running Ductwork Through a Wall
Start by mounting the hood itself to the wall or underside of a cabinet, following the manufacturer's instructions. Use a stud finder to locate wall studs, then drill pilot holes and find the mounting bracket with the bolts or screws provided. The hood should sit 28 to 36 inches above your cooktop — check your manual for the exact height. Use a level to confirm it is straight before tightening all fasteners.
Next, locate where the ductwork will exit the exterior wall. Measure from the hood's duct collar (the opening where air enters the duct) straight back to the outside wall, accounting for any bends or obstacles. Mark the exit point on the outside wall, then drill a pilot hole from inside to outside so you can see where to cut. From outside, use a drywall saw or reciprocating saw to cut a hole slightly larger than your ductwork diameter — typically 6.5 inches for a 6-inch duct. Wear a dust mask and eye protection.
Slide the wall cap (the exterior trim ring) over the hole from outside, then run your ductwork from the hood's collar to the wall cap opening. find each section of duct with duct clamps, tightening them firmly so air does not leak at the seams. Caulk around the wall cap on the outside to seal gaps and prevent water and pests from entering. Do not use expanding foam — it traps moisture and can degrade over time.
Venting Through the Roof
Roof venting works the same way as wall venting up to the point where the duct reaches the roof. Measure from the hood's collar to the roof opening, accounting for vertical rise and any horizontal runs. Mark the exit point on the roof from inside (drill a pilot hole so you can see it from above), then go to the roof and cut the hole using a reciprocating saw or jigsaw. Make the hole slightly larger than your ductwork diameter.
Slide the roof flashing (a metal ring with a sloped collar) over the hole from above, then run your ductwork up through it. find the ductwork with clamps, then nail or screw the flashing to the roof decking using the pre-drilled holes in the flashing. Seal all gaps between the flashing and roof with roofing cement or silicone caulk rated for outdoor use — this is critical to prevent leaks. Do not rely on caulk alone; the flashing itself is what keeps water out.
Roof installations are more durable long-term because they do not collect standing water the way wall caps sometimes do, but they are also more visible and require you to work at height. If your hood is more than one story above the roof, or if your roof is steep or complex, hire a roofer to handle the flashing installation.
Connecting Ductwork and Sealing Leaks
Whether you vent through a wall or roof, every joint in your ductwork must be sealed. Use duct clamps (metal bands with a screw mechanism) at every connection point, tightening them until the duct is compressed slightly. Flexible ductwork should be clamped at both ends of each section; rigid duct should be clamped at every joint.
After clamping, run your hand along the outside of the ductwork to feel for air leaks. If you feel air escaping, tighten the clamp or add a second clamp. For small gaps, wrap the joint with aluminum foil tape (not duct tape — it degrades in heat). Do not use mastic or caulk inside the ductwork; these materials can trap grease and create fire hazards.
Check that your ductwork slopes slightly downward as it runs away from the hood. This prevents condensation from pooling inside the duct and dripping back into your hood. A slope of 1/4 inch per foot is standard. If your ductwork runs horizontally for a long distance, install a drip loop — a small downward bend in the duct — at the lowest point to collect condensation.
Electrical Connection and Testing
Most range hoods plug into a standard outlet, so if an outlet is already installed near your hood, straightforward plug it in. If you need to install a new outlet or hardwire the hood to a circuit breaker, hire a licensed electrician. Do not attempt to run new circuits yourself unless you have experience with electrical work.
Once everything is connected, turn on the hood and listen for unusual noise or vibration. The motor should run smoothly without rattling. Place your hand near the exterior wall cap or roof vent opening and confirm that air is flowing out — you should feel a steady stream. If air is not flowing, check that the damper (a flap inside the wall cap) is opening freely. Some dampers stick if they are installed upside down or if they are clogged with dust.
Run the hood for 10 to 15 minutes and check for any visible air leaks around the ductwork or at the wall cap. If you see dust or feel air escaping, tighten clamps or add more tape. Turn off the hood and let it cool, then inspect the interior of the ductwork if possible — you should see no gaps or loose sections.
Maintenance After Installation
Range hood vents collect grease over time, especially if you cook frequently. Clean the exterior wall cap or roof vent every three to six months by removing any visible buildup. If you used flexible ductwork, inspect it annually for kinks or damage that could restrict airflow. Rigid ductwork lasts longer and traps less grease, so if you are installing a new hood, rigid duct is the better choice even though it costs more upfront.
If your hood has a grease filter, clean or replace it according to the manufacturer's schedule — usually every one to three months depending on cooking frequency. A clogged filter forces the motor to work harder and reduces airflow, which defeats the purpose of the hood. If you notice the hood is not pulling steam or smoke as well as it did when new, the ductwork is likely clogged and needs cleaning.
Common Installation Mistakes to Avoid
The most common mistake is venting into the attic or crawlspace instead of to the outside. This traps moisture and grease inside your home, leading to mold, rot, and pest problems. Every range hood vent must terminate outside, period. The second mistake is using flexible ductwork that is too long or too kinked — this restricts airflow and makes the motor work harder. Keep flexible duct runs under 25 feet and avoid sharp bends.
A third mistake is failing to seal the wall cap or roof flashing properly. Water will find its way in through gaps, so spend time caulking and sealing. Fourth, do not use duct tape on ductwork joints — it fails in heat and leaves sticky residue. Use duct clamps and aluminum foil tape instead. Finally, do not forget to slope the ductwork downward or install a drip loop; condensation that drips back into your hood will eventually damage the motor.
Frequently Asked Questions
Can I vent my range hood into the attic instead of outside?
No. Venting into the attic traps moisture and grease, which causes mold, wood rot, and attracts pests. Range hoods must vent to the outside of your home. If you cannot reach an exterior wall or roof, consult a contractor about extending your ductwork or relocating the hood.
What size ductwork do I need?
Most residential range hoods use 6-inch diameter ductwork, but check your hood's manual to confirm. Some high-powered commercial-style hoods use 8-inch duct. Using undersized ductwork restricts airflow and reduces the hood's effectiveness.
Is flexible or rigid ductwork better?
Rigid ductwork is more durable and traps less grease, so it requires less cleaning. Flexible ductwork is easier to route around obstacles but should not exceed 25 feet in length. For most kitchens, rigid duct is the better long-term choice if your layout allows it.
Do I need a damper in the wall cap?
Yes. A damper is a flap that opens when the hood runs and closes when it is off, preventing outside air and pests from entering your kitchen. Most wall caps and roof vents include a damper. Confirm it opens and closes freely during testing.
How long does a range hood vent installation usually take?
A straightforward wall installation typically takes three to five hours, including mounting the hood, cutting the hole, running ductwork, and sealing. Roof installations take longer because flashing installation is more involved. If you are inexperienced with tools, add extra time or hire a contractor.