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.
Venting clothes dryer into roof.
But we don t recommend it for two reasons.
When venting dryers for long distances use rigid metal pipe with as few elbows as possible.
After the snow melts below the vent it ll probably freeze again farther down on the roof.
Dryer vent specialists will tell you that a vertical approach to installing a dryer vent is inefficient and creates a fire risk for a home if it goes unchecked.
Doing so would fill your attic with warm moist air that could rot the framing.
The international residential code allows you to run a dryer vent through the attic but you can t terminate it there.
This is one of the most common mistakes we see from people who are not experienced with air ducts.
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.
When bath fans and clothes dryers vent through the roof they melt a bunch of snow.
Every turn increases friction loss unless you use non restrictive elbows.
For dryer efficiency and safety the shortest and straightest ducting route is always best.
Be careful you don t cut through any studs electrical wires or pipes in the process.