Key takeaways
- A common code planning figure is about 35 feet
- Each elbow takes away allowed length
- Your dryer manual and local code decide
- Shorter and straighter is always better
The planning figure
A common code figure is a maximum of about 35 feet of duct from the dryer to the outside, reduced for each bend. Many codes reduce the limit by about 5 feet for each 90-degree elbow and by about 2.5 feet for each 45-degree elbow.
Your dryer maker may set a different limit in the manual, and your local building department has the final word.
Counting your own run
Measure the straight sections, then add the equivalent length for each elbow. A 20-foot run with three 90-degree elbows already counts as about 35 feet.
Our Vent Run Builder lets you draw the route and shows the effective length against the planning figure.
When the run is too long
If the run is longer than it should be, options include a shorter route through a closer wall, a recessed box that saves a bend, or, where allowed, a booster fan made for dryers.
Shorter is almost always the best fix.
Related services
Quick answers
Do elbows really matter that much?
Yes. Every bend slows the air and gives lint a place to settle.
Can I use a longer vent with a stronger dryer?
A stronger dryer does not change the code limit. Check your manual and local code.
Ready to talk it through? Get a free quote or call 800-313-8481.