Ask This House Heating and plumbing expert Richard Trethewey to visit Cleveland to route a dryer vent.
How to Vent a Clothes Dryer
Mark the location of the rigid pipe that will vent to the exterior.
To determine the drilling location from outside, drill a pilot hole through this marked area.
Drilling through vinyl siding requires that you set the drill in reverse. Then, use the spot saw to score the hole lightly.
Place the exercise in the right direction and drill the hole. Do not cut through the hole from the opposite side.
Now, prepare the remaining hole from the inside. This will make sure the spot appears clean from both sides.
Cut the rigid vent pipes to the required size. Use duct tape to seal the seams.
Place the tube inside the dryer vent cover. Use more duct tape to seal the seam.
Insert the pipe from the outside into the hole. Attach the vent cover to your exterior wall using screws. To prevent pests from entering, you can also add a critter cover to the dryer vent cover.
The other end of the pipe should be inserted into a dryer vent elbow. Seal it with duct tape.
Place the dryer in its original position. Attach the dryer vent to your elbow with a clamp or a screwdriver.
Re-insert the dryer.
Resources:
Richard suggests keeping dryer vents as short and clean as possible to avoid lint accumulating and clogging them. You can find all the parts Richard needed to install the vent at your local home center, including the duct tape, rigid pipe elbows, and duct cover.
Q: Previous owners moved the laundry room to the second floor and terminated the dryer vent in the attic space above since it’s not near an exterior wall. What’s the best way to vent it to the outside?
Richard uses straight-cut tin scissors to cut through the steel dryer duct.
Colleen McQuaid
A: While it’s popular to have laundry rooms on the second level, venting clothes dryers into the attic is a huge mistake. The warm, humid air from the vent can cause mold growth on the roof framing, sheathing, and other items stored in the space. The damp air from the vent will condense on cold surfaces in cooler temperatures, which can soak insulation and cause damage to the ceiling below. All that warmth can also lead to ice dams in snowy areas.
These problems can be avoided by using the roof as the direct route to the outside. You will need to connect the dryer’s ductwork to a roof vent with a flexible hood.
Even if you have an asphalt-shingled roof, installing such a vent is best left to a professional with the proper equipment to protect your fall and know how to flash around roof penetrations. After the duct has been installed on the roof, connect it from the attic to the dryer conduit. Foil tape can seal the vent and seams in duct connections. Use a fire-stop sealant like Fire Barrier Cp 25WB+ made by 3M to fill the area where the duct enters the attic. Wrap the metal in R-8 duct insulation for internal condensation.
The duct can also be run to an exhaust vent on an exterior wall, at least 3 feet away from a door or window. Straight duct runs can be as long as 35ft. However, dryers will need to subtract 5ft for each 90-degree turn that the duct makes. The dryer should be within reach of an exterior wall. If it is, a handyperson can cut a hole in the duct and connect it to the vent. No matter which direction your duct runs, make sure it is made of 4-inch galvanized metal. The duct’s smooth walls allow for good airflow and keep lint buildup at a minimum. They are also fire-resistant. Tint-trapping corrugations made of flexible plastic or foil-faced flexible conduits pose a danger to fire and slow the airflow. This increases drying time and makes the dryer motor work harder.