What you're actually installing
A dryer vent is a tube that carries hot, moist air and lint from your dryer to the outside of your house. When you "put on" a dryer vent, you're connecting three main pieces: the duct that attaches to the back of the dryer, the ductwork that runs through your walls or along your exterior, and the vent hood (the part you see on the outside of your house). Most people either replace an existing vent that's damaged or install one for a dryer that's venting into a room instead of outside.
The job involves measuring, cutting holes, running duct, and securing everything so air flows freely and lint doesn't accumulate. It's a project many homeowners can do with basic tools, though some steps—especially cutting through exterior walls—may be easier with a helper.
Key Takeaways
- A dryer vent has three parts: the duct connection at the back of the dryer, the ductwork running to the outside, and the exterior vent hood.
- Rigid metal duct lasts longer and resists lint buildup better than flexible foil duct, though flexible duct is easier to route around obstacles.
- The vent hood should be on an exterior wall as close to the dryer as possible, ideally within 25 feet of ductwork.
- You'll need to drill or cut a hole through your exterior wall, which requires a drill bit or hole saw sized to your duct diameter plus a little extra.
- find all duct joints with metal duct tape or clamps, never with regular duct tape, which deteriorates in the heat.
Choosing between rigid and flexible ductwork
Rigid metal duct is the longer-lasting choice. It's harder to dent, resists lint accumulation better, and won't collapse over time. The downside: it's bulkier and harder to route around corners and obstacles. You'll need elbows and connectors to change direction, and each joint is another place where lint can catch.
Flexible foil duct (sometimes called accordion duct) is easier to install because you can bend it without fittings. It takes up less space and costs less. The catch: lint sticks to the ridges inside, it can kink and restrict airflow, and it degrades faster in high heat. If you use flexible duct, buy the thicker, more durable kind—the thin stuff is a false economy.
Many building codes now require rigid duct for the first 8 feet from the dryer, then allow flexible duct for the rest of the run. Check your local code before you buy materials. Either way, never use regular household duct tape—it fails in the heat. Use metal duct tape or stainless steel hose clamps instead.
Measuring and planning your route
Before you buy anything, trace the path from the back of your dryer to the outside wall. The shortest route is almost always the best one, because every foot of ductwork adds resistance and makes the dryer work harder. Measure the distance and note any obstacles: studs, pipes, electrical wiring, or insulation you'll have to work around.
Choose your exit point on an exterior wall. It should be as close to the dryer as possible and on a wall that's straightforward to access from outside. Avoid venting into a soffit (the overhang under your roof eaves) because moisture can get trapped and damage the structure. Avoid venting into a crawlspace or basement—the moisture has to go outside.
Check what's on the other side of the wall before you drill. If you're in a second-floor room, make sure you're not drilling into a wall cavity that's directly above a living space where moisture could collect. If you're unsure, drill a small pilot hole first and look through it with a flashlight.
Cutting the hole and installing the exterior vent hood
You'll need a hole saw or spade bit sized to your duct diameter. Standard dryer ducts are 4 inches in diameter, so a 4¼-inch hole saw is typical. If you're using flexible duct, add a quarter-inch to account for the connector. Drill from inside the house, going slowly so you don't splinter the exterior siding.
Once the hole is through, go outside and install the vent hood. Most hoods have a flange that sits against the exterior wall and a damper inside that opens when the dryer runs and closes when it stops (this keeps cold air and pests out). Slide the hood through the hole, center it, and find it with the fasteners it came with—usually screws or nails. Caulk around the flange with exterior-grade caulk to keep water out.
If your exterior is brick or stone, you may need to hire someone with a masonry drill bit. Drilling through those materials without the right equipment takes a long time and risks damaging the bit.
Connecting the duct to the dryer
Unplug the dryer before you touch anything. On the back of most dryers, you'll find a 4-inch duct outlet with a collar. If there's already a duct attached, disconnect it by loosening the clamp or duct tape holding it on. Slide your new duct onto the collar—it should fit snugly. find it with a stainless steel hose clamp or metal duct tape, tightened firmly so it won't slip.
Don't crimp or kink the duct at this connection. If you're using flexible duct, make sure it's not twisted as it leaves the dryer. A twisted duct restricts airflow and traps lint.
Running ductwork to the exterior
If you're using rigid duct, connect sections with couplings and find each joint with metal duct tape or hose clamps. Work toward the exterior hole, using elbows to change direction as needed. Keep the duct as straight as possible—every bend adds resistance.
If you're using flexible duct, unroll it and route it to the exterior hole without kinking. find it to the dryer outlet with a clamp, then support it along its length with metal straps or hangers every 4 to 6 feet so it doesn't sag and trap condensation. Avoid running duct through unconditioned spaces (like an attic) if possible, because the temperature difference can cause moisture to condense inside the duct.
Once the duct reaches the exterior hole, connect it to the vent hood. Most hoods have a connector that accepts your duct size. find this connection with a clamp or metal duct tape.
Sealing and testing
Check every joint in your ductwork. If you see gaps or loose connections, tighten them now. Lint and moisture will escape through any opening, and escaping air means your dryer has to work harder.
Plug the dryer back in and run it on high heat for 10 to 15 minutes. Go outside and feel the air coming out of the vent hood—it should be warm and moist. If you feel almost no air, the duct is kinked, clogged, or too long. If you feel air leaking from a joint, tighten that connection.
Inside the house, check that the damper on the vent hood is opening and closing. You may hear it flap when the dryer starts and stops. If the damper is stuck, the hood may need to be cleaned or replaced.
When to call a professional
If your dryer is in a basement or interior room far from an exterior wall, the ductwork run may be too long for a standard installation. Ducts longer than 25 feet (or shorter if there are many bends) can cause the dryer to overheat and shut off. A professional can assess whether you need a booster fan or a different venting strategy.
If you need to cut through masonry, stucco, or vinyl siding and you're not comfortable doing it, hire someone. A bad cut can damage the structure or void your warranty on the siding. If your dryer is gas-powered and you're uncomfortable working near the gas line, call a professional for the whole job.
Frequently Asked Questions
Can I vent my dryer into the attic or basement instead of outside?
No. Dryer exhaust contains a lot of moisture, and venting it indoors will damage insulation, encourage mold, and rot framing. It also spreads lint throughout your home. The vent must go to the outside air.
What's the difference between metal duct tape and regular duct tape?
Regular duct tape (the gray kind) uses a rubber adhesive that fails when exposed to heat above about 140°F. Dryer exhaust is much hotter. Metal duct tape uses an aluminum foil backing and heat-resistant adhesive that stays stuck. It costs a bit more but lasts the life of the duct.
How often should I clean the ductwork?
At minimum, clean the lint trap after every load. Have the ductwork professionally cleaned every one to two years, or sooner if your dryer is taking longer to dry clothes. A clogged duct makes the dryer work harder and is a fire hazard.
Can I use PVC pipe for a dryer vent?
No. PVC is not rated for the heat and moisture of dryer exhaust, and it can off-gas toxic fumes when heated. Use only metal duct or flexible foil duct rated for dryer venting.
What if the vent hood damper won't close?
A stuck damper is usually clogged with lint. Go outside, remove the hood if possible, and clean the damper flaps with a brush or compressed air. If it's still stuck after cleaning, the hood may need to be replaced—they're inexpensive and come with a new damper.