A dryer duct should be 25 feet or less. Subtract 5 feet for each 90-degree turn and 2 1/2 feet for each 45-degree turn. Because washer and dryer pedestals have a higher height, they can require a shorter length of ductwork. Adjust your final duct work measurements for these types of appliances.
Dryer vent runs should be no longer than 25 feet per most code requirements and manufacturer recommendations. For each bend, add 3-5 feet. Additionally, as mentioned, going through the roof requires more power and a booster fan may be necessary. Ideally, it should vent through a wall to the outside.
A long dryer vent also provides more area for the collection of lint. Therefore, it is better to keep the vent shorter. Fewer spaces between the dryer and the wall may prevent smooth airflow, thereby leading to the dryer's heat up. One requires special brushes for thorough dryer vent cleaning.
Keep exhaust duct as straight and short as possible. Exhaust systems longer than the manufacturer's recommendations can extend drying times, affect appliance operation and may encourage lint build-up on pipe lining. More Dryer Vent Cleaning information can be found here.
The female end of each tubing should be on the end closest to the dryer. This prevents lint from snagging on the sharp metal on the way through the vent system and creating a clog (a big fire hazard). With the female ends upstream, there won't be any sharp ends to catch on.
The maximum developed length of a clothes dryer exhaust duct shall not exceed 35 feet from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet for each 45-degree (0.8 rad) bend, and 5 feet for each 90-degree (1.6 rad) bend.
Codes and Standards
In the United States, most home inspectors refer to the International Residential Code (IRC) M1502 for dryer venting. However, some states may have additional regulations. The International Mechanical Code (IMC) 504 also includes extensive clothes dryer requirements.
The International Association of Certified Home Inspectors (InterNACHI) establishes length requirements for dryer vents. The length cannot be more than 25-feet; it should also be as straight as possible. If there is a 90-degree angle in the vent, then it shouldn't be more than 20-feet.
Rigid metal options are the best types of dryer vent hoses. They are sturdy and completely smooth, meaning they catch the least amount of lint. If you're looking for the safest, smartest option, rigid metal dryer vent hoses should be your go-to.
A long dryer vent hose will impede the efficiency of your dryer, make the clothing take longer to dry, and may affect the automatic drying cycles on newer dryers. So when making decisions about where and how to vent a dryer, consider placing a dryer close to an exterior wall to make efficient venting easy.
Where space is limited, an adjustable offset dryer vent is used. It's also called a periscope dryer vent. Offset vents allow the dryer to be installed closer to the wall than a typical basement installation, using a 90-degree, 4-inch duct elbow on the dryer's discharge vent.
A shorter dryer hose can increase the efficiency of your clothes dryer, lengthen its lifespan and help you save on energy bills.
It is not safe. Vent hoses are necessary for dryers to operate properly because they allow heat, lint, and humidity to be vented outdoors. When a dryer is used without one of these vent hoses, moisture and lint can build up inside the appliance and even cause a fire.
Ideally, your dryer should have exhaust vents that lead outside to keep your laundry area clean and less humid. The most common place to vent your dryer is horizontally through the exterior wall near the dryer, which is the ideal placement.
Metal tape can also be used to secure the flexible aluminum duct, too, but clamps make it easier to remove the tubing for cleaning. Aluminum foil duct is inexpensive and relatively easy to work with, but its ribbed walls can trap lint, a potential fire hazard.
The maximum developed length of a clothes dryer exhaust duct shall not exceed 35 feet from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet for each 45-degree (0.8 rad) bend, and 5 feet for each 90-degree (1.6 rad) bend.
If yours is too long, you can use scissors to cut the hose and wire clippers to cut the circular wire that gives the hose its shape. Make sure to attach the clamps! Usually dryer vent hoses come with clamps.
Route the dryer vent horizontally to the home's outside wall. Duct work should pitch 1/4-inch per foot to the outside. This keeps moisture out of the pipe. For basement laundry areas where your ductwork will run vertically to the outside wall, you may need to use 90-degree elbows.
Some dryers can exhaust beyond 25 equivalent feet without a booster fan. Dryer Duct Booster Saves significant energy - reduces drying times 50% or more. Reduces lint build-up, dust & fire hazards by maintaining proper velocity in duct runs up to 150 equivalent feet.
Here's a quick rundown: If you can't vent your dryer outside, there's a risk of fires due to lint buildup, a chance for mold to grow, your laundry room might get too hot, and drying times could increase, possibly causing damage to your clothes and higher energy bills.
Per the requirements of the International Residential Code, Section M1502 (2009-2021 IRC), the clothes dryer exhaust duct should be a rigid or semi-rigid metal duct made of galvanized steel or galvanized aluminum with a smooth interior finish and a duct diameter of 4 inches.
There are variables that affects how often you should clean your dryer vent system. Generally speaking, the clothes dryer itself, as well as the vent should be cleaned every 1 to 3 years.