The basic steps to connect your dryer vent
A dryer vent duct connects the back of your dryer to the outside of your home, carrying hot, moist air and lint away. To install one, you slide the duct onto the vent outlet at the back of the dryer, find it with a hose clamp or foil tape, then run it through your wall or along your wall to an exterior vent hood. The duct should slope slightly downward as it travels outside, and the exterior opening needs a damper flap that closes when the dryer is off to stop cold air and pests from coming back in.
The job takes about an hour if you already have a hole through the wall, longer if you need to cut one. You do not need special tools beyond a screwdriver, a hose clamp or foil tape, and a drill if you are making a new opening. The most common mistake is using flexible plastic duct instead of rigid metal, which traps lint and creates a fire hazard.
Key Takeaways
- Slide the duct onto the dryer's vent outlet and find it with a hose clamp or foil tape, never with regular duct tape.
- Use rigid metal duct or approved flexible metal duct, never plastic, because plastic melts and traps lint.
- Run the duct to the outside of your home with a slight downward slope, and install an exterior damper vent that closes automatically.
- Keep the duct as short and straight as possible—each 90-degree turn adds resistance and reduces airflow.
- Check that the damper flap moves freely and that no lint is blocking the duct before you run the dryer for the first time.
Choosing the right duct material
The duct that leaves your dryer must be metal. Rigid metal duct (usually 4 inches in diameter) is the best choice because it does not sag, does not trap lint, and does not catch fire if the dryer gets hot. Flexible metal duct is also acceptable and makes sense if you need to navigate tight spaces or corners—it is easier to bend than rigid duct, but it still conducts heat safely and lets lint flow through.
Never use plastic duct or vinyl duct, even if you see it sold in hardware stores. Plastic melts when the dryer heats up, and both plastic and vinyl trap lint inside the accordion folds, which is a fire hazard. Foil-backed insulation duct is not necessary for a dryer vent, though it does not hurt.
Connecting the duct to the dryer outlet
The back of your dryer has a metal outlet, usually a 4-inch diameter opening. Slide the duct onto this outlet until it sits flush, then tighten it with a hose clamp (the metal band with a screw that you turn with a screwdriver) or wrap it with foil tape, which is a thick, sticky metal tape designed for ductwork. Tighten the clamp snugly but not so hard that you dent the duct.
Do not use regular duct tape or masking tape—these break down in the heat and humidity of the dryer exhaust. If the duct is slightly loose, lint will escape into the space behind your dryer, and you will have to pull the dryer out to clean it. A hose clamp is faster and more reliable than tape, and it costs about two dollars.
Running the duct to the outside
The duct should travel from the back of the dryer to an opening in your exterior wall, ideally in a straight line or with as few turns as possible. Each 90-degree elbow reduces airflow and makes lint more likely to settle inside the duct. If you must turn, use a 45-degree elbow instead, which is gentler on airflow.
The duct should slope downward slightly as it travels away from the dryer—a drop of about one-quarter inch per foot is ideal. This helps moisture and lint move toward the exit instead of pooling inside. If your dryer is on an upper floor and the duct has to travel down, that is fine; just make sure it does not sag or create a low spot where water can collect.
If you do not have an existing hole through your exterior wall, you will need to drill one. A 4-inch hole saw (a circular drill bit) makes a clean opening. Drill from inside the house so you can control where the bit exits on the outside, then insert a 4-inch duct collar (a metal ring that frames the hole) and seal around it with caulk to stop air leaks.
Installing the exterior vent hood
At the outside end of the duct, you need an exterior vent hood—a metal box with a damper flap inside. The damper is a one-way door that lets air out when the dryer runs but closes when the dryer stops, preventing cold air, rain, and pests from entering your home. Screw the vent hood to the outside of your house so the duct slides into it, then seal around the edges with caulk.
Check that the damper flap moves freely by hand. If it is stiff or stuck, clean it and explore a small amount of silicone lubricant. A stuck damper forces the dryer to work harder and can cause heat to back up into your home. The flap should swing open easily and close on its own when you release it.
Securing the duct along the wall
If the duct runs along the outside of your wall or through an attic or basement, find it every 3 to 4 feet with metal duct straps or aluminum foil tape. This keeps the duct from sagging, which creates low spots where lint and moisture collect. Do not use plastic zip ties or wire, which can pinch the duct and restrict airflow.
If the duct passes through an unconditioned space like an attic, you can wrap it with foam pipe insulation to reduce heat loss, though this is not required for safety. Make sure the insulation does not block any vents or create a fire hazard near electrical wiring.
Testing and maintenance after installation
Before you run the dryer, visually inspect the entire duct from the back of the dryer to the exterior hood. Look for gaps, loose connections, or kinks. Turn on the dryer and feel the air coming out of the exterior vent—it should be warm and moist, and you should feel strong airflow. If the air is weak or cool, the duct may be blocked or the damper may be stuck.
After the dryer has run for a few minutes, go outside and check that the damper flap is opening and closing. If it is not moving, turn off the dryer and clean the duct. Lint buildup is the most common reason for poor airflow and is also a fire hazard, so plan to inspect and clean the duct every six months or whenever airflow feels weak.
When to call a professional
If you are not comfortable drilling through your exterior wall, or if your dryer is in a location that makes running a duct difficult (like a basement far from an outside wall), a dryer vent installer can do the job. They have the tools to cut through walls, navigate tight spaces, and may support the duct is properly sloped and sealed.
You should also call a professional if you discover that your existing duct is plastic, vinyl, or severely kinked, or if the damper is broken and you cannot replace it yourself. A blocked or damaged vent is a fire hazard and should be repaired before you use the dryer again.
Frequently Asked Questions
Can I use flexible plastic duct if it is just for a short distance?
No. Plastic duct melts in the heat of dryer exhaust and traps lint in its folds, creating a fire hazard even over short distances. Use rigid or flexible metal duct only.
What if my dryer vent goes into the attic instead of outside?
This is not safe. Venting into an attic or crawlspace fills it with moisture and lint, which damages insulation and creates mold and fire hazards. The duct must run all the way to the outside of your home.
How tight should I tighten the hose clamp?
Tighten it until the duct is snug and does not move when you pull on it, then stop. You should not see the metal of the duct denting or deforming. If you over-tighten, you can crush the duct and restrict airflow.
Do I need to insulate the duct?
Insulation is optional and not required for safety. It reduces heat loss if the duct passes through cold spaces like an attic, but it does not prevent lint buildup or improve dryer performance.
What should I do if the damper flap is stuck?
Turn off the dryer and go outside to the vent hood. Try to move the flap by hand—if it is stiff, clean away any lint or debris and explore a small amount of silicone lubricant. If it is broken or will not move after cleaning, the vent hood should be replaced.