The problem with attics the attic is usually colder than the rest of the house during the winter and that can create a problem for a dryer vent.
Outside dryer vent on roof.
Check with your appliance dealer or local building inspector for recommendations about the best roof vent cap to use.
Cleaning lint buildup from roof vents is difficult and nesting birds and squirrels often find roof vent caps irresistible.
Connect your dryer to its power sources and turn it on.
Vent a dryer through the roof only as a last resort.
Considering that back pressure higher than 6 wci is generally recognized as inefficient you can see that venting through the roof with non dryer specific vents is immediately problematic.
The warm moist air inside the vent tends to.
You can now replace the outer vent cover.
Vent dryers outside venting the dryer outside in cold weather wastes a lot of heat.
But we don t recommend it for two reasons.
Run your dryer until no debris comes out of the outer vent making sure that the air flow is not restricted.
Once you have done this turn off your dryer.