Venting the dryer outside in cold weather wastes a lot of heat.
Venting clothes dryer into roof.
When venting dryers for long distances use rigid metal pipe with as few elbows as possible.
To make the dyer more efficient you can buy an inexpensive heat diverter and install it in the exhaust duct of electric dryers only not gas dryers you ll save about 50 worth of heat per load in the winter.
But we don t recommend it for two reasons.
Every turn increases friction loss unless you use non restrictive elbows.
If venting outside isn t an option you can vent the dryer out of the attic through the roof using a special roof vent to keep rain out.
The international residential code allows you to run a dryer vent through the attic but you can t terminate it there.
For dryer efficiency and safety the shortest and straightest ducting route is always best.
Air velocity reduction from friction loss promotes lint build up and makes the dryer work harder to completely dry each load.
Be careful you don t cut through any studs electrical wires or pipes in the process.
Doing so would fill your attic with warm moist air that could rot the framing.
This is one of the most common mistakes we see from people who are not experienced with air ducts.
When bath fans and clothes dryers vent through the roof they melt a bunch of snow.