The Basic Route: Drilling Straight Through the Wall

A range hood vent through the wall is the most direct path for cooking exhaust to leave your kitchen. You drill a hole from inside the kitchen through the exterior wall, run ductwork through it, and seal the opening. The job takes a weekend if you have the right tools and no obstacles — studs, pipes, or electrical wiring — in your path.

Before you drill, you need to know what's inside your wall. Use a stud finder to locate the wooden framing. Check for pipes and wiring with a wire tracer or by turning off circuits and testing outlets. If you hit a stud, you'll need to cut it out and frame around the opening, which adds complexity and sometimes requires a permit. If you hit plumbing or electrical, stop and reroute your ductwork to a clear section of wall.

The hole itself should be 6 to 8 inches in diameter for most range hoods, though check your hood's manual for the exact size. A drywall saw cuts through the interior, and a hole saw or reciprocating saw handles the exterior sheathing and siding. Measure twice from the inside and outside to make sure the holes line up.

Key Takeaways

  • Locate studs, pipes, and wiring before drilling so you don't cut into them and create a bigger repair job.
  • The hole diameter depends on your hood's ductwork size, usually 6 to 8 inches; check the manual before you start.
  • Seal the gap between the ductwork and the wall opening with caulk or foam to stop air leaks and pest entry.
  • A damper or check valve inside the ductwork prevents outside air from flowing backward into your kitchen when the hood is off.
  • If a stud is in the way, you may need a permit and a structural engineer's sign-off before cutting it out.

Choosing the Right Ductwork and Damper

Rigid metal ductwork is stronger and moves air more efficiently than flexible duct, but it's harder to route around obstacles. Flexible duct bends easily and costs less, but it can sag if not supported and traps grease more readily. Most builders use a mix: rigid ductwork from the hood to the wall, then flexible duct through the wall opening if the path isn't straight.

A damper or check valve sits inside the ductwork near the wall opening. When the hood runs, it opens and lets air out. When the hood stops, it closes and blocks outside air, rain, and pests from flowing back into your kitchen. Some hoods have a built-in damper; others require you to buy one separately. A damper costs $20 to $50 and takes five minutes to install.

Ductwork diameter must match your hood's outlet. Most residential hoods use 6-inch or 8-inch duct. Undersizing the duct makes the hood work harder and move less air. Oversizing wastes money and makes the hood noisier. Measure the outlet on your hood before you buy any duct.

Cutting and Sealing the Wall Opening

Mark the center point of your hole on both the inside and outside of the wall. Use a level to make sure the mark is straight. Drill a pilot hole from the inside all the way through the wall so you can see it on the outside and confirm your location.

From the inside, use a drywall saw to cut through the drywall in a circle. Push the saw straight through without twisting. Once you're through the drywall, switch to a hole saw or reciprocating saw for the sheathing and siding. Work slowly on the exterior to avoid splintering the siding or sheathing.

After the hole is cut, the gap between the ductwork and the wall opening needs to be sealed. Use silicone caulk or expanding foam to fill the space. Caulk is cleaner and easier to explore; foam is faster and fills larger gaps. Either way, seal all the way around the duct so air can't leak in or out. On the exterior, use exterior-grade caulk or foam rated for outdoor use.

Running Ductwork from Hood to Wall

The ductwork path from the hood to the wall opening should be as straight and short as possible. Every bend and every foot of extra duct makes the hood work harder and move less air. If you have to bend the duct, use 45-degree elbows instead of 90-degree ones when you can.

find the ductwork with metal straps or hangers every 3 to 4 feet so it doesn't sag or vibrate. Sag traps grease and condensation, which can drip back into your kitchen or clog the duct. Vibration creates noise and can loosen connections over time.

Connect each section of ductwork with self-tapping metal screws or duct clamps. Don't use duct tape — it dries out and fails within a year. Wrap the seams with aluminum foil tape if you want extra insurance against leaks, but screws or clamps alone are standard and sufficient.

Installing the Wall Cap and Exterior Trim

A wall cap or roof flashing covers the hole on the outside and keeps rain and pests out. The cap slides over the ductwork and is screwed or caulked to the siding. Most caps come with a damper built in, though you may have already installed one inside the duct.

Position the cap so water runs off it and away from the wall. On a vertical wall, the cap should sit flush against the siding with the bottom edge slightly lower than the top so rain sheds downward. Caulk around the cap with exterior-grade silicone to seal the gap between the cap and the siding.

On the interior, you can leave the hole as is if the ductwork covers it, or install trim ring or escutcheon plate for a finished look. Trim rings are optional and mostly cosmetic, but they hide the gap and make the installation look intentional.

Permits and When You Need Them

Permit rules vary by city and county. Some places require a permit for any exterior wall penetration; others only require one if you're cutting a stud or if the hood is part of a larger kitchen remodel. Call your local building department before you start and ask whether a range hood vent installation needs a permit in your area.

If you do need a permit, the inspector will check that the ductwork is the right size, that the damper is installed, and that the wall opening is sealed properly. An inspection usually costs $50 to $150 and takes a few days to schedule. If you skip the permit and the work is discovered later, you may have to redo it at your own cost or face a fine.

If a stud is in the way, you almost certainly need a permit and possibly a structural engineer's approval before cutting it. A stud carries the weight of the wall above it, and cutting it without proper support can cause the wall to sag or crack. A professional can frame a header to carry the load, but this adds $200 to $500 to the job and requires a permit.

Troubleshooting Common Installation Problems

If the ductwork doesn't fit through the hole, the hole is too small. Measure the ductwork diameter and make sure the hole is at least that wide, plus a quarter inch on all sides for the wall cap. If the hole is already cut, you can enlarge it with a hole saw or jigsaw, but this is messier than getting it right the first time.

If air leaks around the ductwork, the gap isn't sealed. Caulk or foam any visible space between the duct and the wall opening. If the leak is on the exterior, use exterior caulk. If it's on the interior, interior caulk is fine, but exterior caulk works everywhere.

If the hood is noisy, the ductwork may be vibrating against the wall or a stud. Add a rubber isolator or vibration damper where the duct passes through the wall. These cost $10 to $30 and reduce noise significantly. Alternatively, wrap the duct in fiberglass insulation to dampen vibration.

Frequently Asked Questions

Can I vent the range hood into the attic instead of through the wall?

No. Venting into the attic traps moisture and grease, which rots wood, promotes mold, and attracts pests. All range hoods must vent to the outside. If venting through a wall is not possible, vent through the roof or soffit instead.

What if there's a stud directly in the path of my ductwork?

You have two options: reroute the ductwork to a clear section of wall, or cut the stud and frame a header to carry the load above. Rerouting is simpler and cheaper. Cutting a stud requires a permit and usually a structural engineer's approval, which adds time and cost.

Do I need a damper if my range hood already has one built in?

No. One damper is enough. If your hood has a built-in damper, you don't need to install another one in the ductwork. If your hood doesn't have one, install a damper in the ductwork near the wall opening.

How do I know if the hole is the right size?

Check your range hood's manual for the ductwork outlet diameter. The hole should be that diameter plus a quarter inch on all sides for the wall cap. Most residential hoods use 6-inch or 8-inch duct, so the hole is usually 6.25 or 8.25 inches in diameter.

Can I use flexible ductwork for the whole run from hood to wall?

Yes, but rigid ductwork is better. Flexible duct is easier to route around obstacles, but it sags over time and traps grease. If you use flexible duct, support it every 3 to 4 feet with hangers so it doesn't sag.