Although dryer venting isn’t complicated, there are some important guidelines you need to follow to protect your health and safety. An improperly vented dryer will release lint and moisture into your home, reducing your air quality. Even worse, incorrect venting can pose a fire hazard.
Materials for a safe, low-maintenance vent
Because of the temperature of the air coming out of your dryer, UL-approved high-temperature metal ducting is the only safe material option. White plastic flex duct may seem like a practical, budget-friendly option, but it accumulates more lint than metal tubing, making it more vulnerable to fire. It’s also not very durable, so you’ll have to replace it more often.
Your best options are:
- Spiral-wound aluminum flex duct – Although this is common, it is not ideal because the uneven interior can accumulate lint. Before installing this type of duct, check that your dryer is approved for it.
- Semi-rigid aluminum – This material is similar to flex duct, but it is somewhat better suited for longer venting lengths.
- Rigid Aluminum – The smooth interior of this material makes it an ideal choice for dryer ducts.
- Sheet Metal – This material is harder to install and therefore less common, but its thickness makes it exceptionally durable. Smooth interiors are another benefit.
For most dryers, 4-inch ducting is ideal. If you must bend the duct, install elbows to prevent bends. Never let the duct drag on the ground. Use support rings or bands to fix it to a floor joist or other surface.
Connect the lengths of duct with UL-approved aluminum (foil) tape or metal compression clamps. Screws will only trap lint inside the duct, increasing the risk of fire.
If you plan to run the duct through a conditioned space, such as your crawl space, insulate the duct to prevent condensation from forming in the winter.
The simplest way is to wrap the duct in 2 to 3 inches of fiberglass insulation, but you can also purchase dryer duct insulation sleeves designed for the specific purpose.
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For added protection, consider installing a recessed dryer vent box. This is a metal or plastic box that’s installed in the wall to make room for your dryer vent duct, so it’s less likely to get bent or crushed. It also protects the wall from heat and moisture damage.
By removing the vent, you can push your dryer closer to the wall, freeing up space and creating an overall cleaner appearance.
The outside opening of your vent needs a cover to protect it from cold air, rain, debris such as leaves, and curious wildlife. There are several types of covers available.
- Vent Hood – This simple, angled hood is shaped like the vent hood above your cooking range. The bottom is protected by a damper or grill. The damper opens to vent air from the dryer, but remains closed when the dryer is off.
- Avoid vent hoods covered with grills or screens. These collect lint, which poses a fire risk. They also let in small rodents and insects, debris, and outside air.
- Floating-shuttle cover – In this design, an arm extends out of the vent opening and turns upward at a 90-degree angle. Covering this upward opening is a cup-shaped lid that is pushed upward by the air escaping from the dryer. When the dryer is off, the lid drops back down to seal the hole. This keeps out all kinds of debris.
- Louvered cover – This is a flat cover with one or more slats that is opened by the air escaping from the dryer, but is closed again when the dryer is not in use. It keeps out all types of debris and also saves space compared to other covers.
To improve the vent’s efficiency and protect your wall, apply caulk to seal where the vent meets the outside wall.
Planning Your Dryer Vent Path
The path your dryer vent takes from the dryer to the outside makes a big difference in the vent’s ability to work safely and efficiently. Aim to use the shortest, most direct path possible. This reduces the need for elbows and other bends that can cause lint to accumulate.
If you purchased a dryer vent kit, the instructions should provide guidance about the ideal length.
Whenever possible, keep your vent duct lengths under 25 feet and add elbows only when unavoidable. Bends reduce the length of ducting you can safely use, so reduce your total planned length by 5 feet for each 90-degree turn and 2.5 feet for each 45-degree turn. So if your path includes one 45-degree turn, the duct bend should be no longer than 22.5 feet.
The easiest solution is to move the vent from the wall behind the dryer directly to the outside. If this doesn’t work, move it to the outside from the nearest outside wall.
For dryers in basements, run the duct upward, then horizontally along the ceiling joists to the outside. Keep the outside vent at least 1 foot above the ground for air circulation and to keep the vent clean.
Avoid letting the vent protrude from the roof. This makes it more likely for a blockage to form there, it can attract birds and other nesting animals, and in snowy weather, it will contribute to ice dams that can damage your roof.
Ventilating a dryer is a relatively simple DIY job, but it’s still worth taking some care with. Taking a little time to choose the right material and path for your dryer vent will help your dryer run more efficiently, protect your home from moisture damage and, most importantly, reduce the risk of fire.