The basic path: drill, insert duct, seal, and vent outside
Running a dryer vent through the wall means cutting a hole from your laundry room to the exterior, feeding flexible duct through it, and terminating with a vent hood on the outside. The duct carries warm, moist air and lint out of your home instead of into the attic or crawlspace, which prevents moisture damage and mold. Most installations take a few hours and require a drill, a hole saw, duct tape, and a vent hood kit—all available at hardware stores.
The location of your dryer matters. The shortest path to an outside wall is always better: a 4-foot run loses less heat and lint than a 20-foot run through the house. If your dryer sits on an interior wall, you may need to run vent duct a longer distance, which means more friction, more lint buildup, and more work to keep clean. Check your dryer's manual for the maximum duct length it can handle—most allow 25 feet of straight duct, with 5 feet subtracted for every 90-degree turn.
Key Takeaways
- Drill a hole through the exterior wall large enough for your duct diameter—usually 4 inches—and slope it slightly downward so water does not pool inside.
- Use rigid or semi-rigid duct inside the wall and flexible duct only for the final connection to the dryer, because flexible duct traps lint and can collapse under its own weight.
- Seal the hole around the duct with caulk and install a vent hood on the outside with a damper that opens when the dryer runs and closes when it stops.
- Check and clean the vent hood screen and duct every three months, because lint buildup reduces airflow and can become a fire hazard.
Choosing the right wall and location
Pick an exterior wall that is as close to the dryer as possible. Measure the distance from your dryer's vent outlet to the nearest outside wall. If that wall is shared with a neighbor (in a townhouse or duplex), check your lease or HOA rules—some prohibit venting into shared walls. If you must use an interior wall, plan for a longer duct run and accept that you will clean it more often.
Mark the spot on the outside wall where you want the vent hood. Stand outside and look for a location that is at least 12 inches away from windows, doors, or air intakes, and at least 3 feet above ground level. Avoid spots directly above a patio or deck where lint will fall on furniture. Once you have chosen the spot, go back inside and mark the corresponding spot on the interior wall. This is where you will drill.
Drilling the hole and running the duct
Use a drill with a hole saw bit sized to your duct diameter. Most dryer vents are 4 inches in diameter, so use a 4-inch hole saw. Drill slowly and let the bit do the work—pushing hard will bind the bit and burn out your drill. Once the hole is through, insert the duct from inside. If you are venting through an exterior wall with insulation, you may need to push the insulation aside or remove it from around the hole.
Inside the wall, use rigid or semi-rigid aluminum duct, not flexible duct. Flexible duct is convenient but it sags over time, traps lint in its ridges, and can collapse if the dryer's blower is strong. Rigid duct is straight, smooth, and lasts longer. Connect the rigid duct to the dryer's outlet with a short section of flexible duct—no more than 8 inches—using a hose clamp to tighten the connection. This short flex section allows the dryer to move slightly without stressing the duct.
On the outside, the duct should slope downward slightly as it exits the wall. This prevents water from pooling inside the duct during humid weather or when the dryer is not running. A slope of 1/4 inch per foot is enough.
Sealing the hole and installing the vent hood
Once the duct is in place, seal the gap between the duct and the wall hole with caulk, not spray foam. Spray foam expands and can crush the duct or create gaps. Use paintable caulk on the inside and exterior caulk on the outside. Smooth it with a wet finger so it sits flush against the duct and wall.
On the outside, install a vent hood with a damper. The damper is a flap that opens when the dryer blows air out and closes when the dryer stops, preventing outside air, insects, and rain from entering the duct. Vent hoods come in different styles—louvered, with a screen, or with a magnetic damper. Avoid hoods with screens that are too fine; they clog with lint and defeat the purpose of venting. Screw the hood to the wall around the duct opening and caulk the seams where the hood meets the wall.
Connecting the duct to your dryer
Most dryers have a vent outlet on the back or bottom. Remove the existing duct (if any) by loosening the hose clamp. Slide the new flexible duct onto the outlet and tighten the hose clamp so it is snug but not so tight that it crushes the duct. Do not use duct tape to seal this connection—it dries out and fails. Hose clamps last longer and hold better.
If your dryer is a gas model, make sure the vent duct does not interfere with the gas line or electrical cord. Gas dryers need clearance for safety. If space is tight, you may need to move the dryer slightly or reroute the duct. Check your dryer's manual for clearance requirements.
Testing airflow and preventing lint buildup
Before you run a full load, turn on the dryer and check that air is flowing out the hood on the outside. You should feel warm air and see the damper flap open. If the damper does not open or airflow is weak, the duct may be kinked, clogged, or too long. Straighten any kinks and check that the duct is not resting on anything that could block it.
Lint buildup is the most common problem. Every time the dryer runs, lint collects inside the duct, on the damper flap, and in the hood screen. Over weeks, this buildup reduces airflow, makes the dryer work harder, and raises the risk of fire. Clean the vent hood screen and damper every three months. Use a brush or compressed air to blow lint out of the hood opening. If you suspect lint deep in the duct, you can use a dryer vent cleaning kit—a flexible brush on a rod that you feed through the duct from inside.
When to call a professional
If you are not comfortable drilling through an exterior wall, or if your wall contains electrical wiring or plumbing that you cannot safely route around, hire a handyperson or HVAC technician. They can locate utilities with a stud finder or wire detector before drilling. If your dryer is in a basement and the nearest exterior wall is far away, a professional can help you plan a longer duct run and may support it is sloped correctly.
If the dryer is in a mobile home or apartment, check your lease or owner's manual first. Some mobile homes have specific venting requirements, and apartments may prohibit exterior modifications. In those cases, a professional installer familiar with your home type can advise you on what is allowed.
Frequently Asked Questions
Can I vent the dryer into the attic instead of outside?
No. Venting into the attic, crawlspace, or garage introduces warm, moist air that causes mold, rot, and structural damage. The moisture also condenses on rafters and insulation, reducing their effectiveness. Always vent to the outside.
What if my dryer is on an interior wall far from the outside?
You can run duct a longer distance, but check your dryer's manual for the maximum length. Most allow 25 feet of straight duct, minus 5 feet for each 90-degree turn. Longer runs mean more lint buildup and more frequent cleaning. If the run is too long, moving the dryer closer to an exterior wall is often simpler than fighting airflow problems.
Do I need a damper on the vent hood?
Yes. Without a damper, cold outside air flows back into the duct when the dryer is off, and insects or rain can enter. A damper flap opens only when the dryer pushes air out. It is a cheap, essential part of any vent hood.
How often should I clean the vent duct?
Check the hood screen and damper every three months. If you see lint buildup, clean it. If the dryer takes longer than usual to dry clothes, the duct is probably clogged and needs cleaning. A clogged vent is a fire hazard and makes the dryer work harder, shortening its life.
Can I use flexible duct for the whole run through the wall?
Flexible duct is convenient but not ideal for long runs inside walls. It sags, traps lint in its ridges, and can collapse. Use rigid or semi-rigid duct inside the wall and flexible duct only for the short connection to the dryer. Rigid duct is straighter, smoother, and easier to clean.