When venting dryers for long distances use rigid metal pipe with as few elbows as possible.
Dryer vent into the attic fixed.
Pitch the attic ductwork back toward the dryer so that any condensation will run back toward the heated space.
Doing so would fill your attic with warm moist air that could rot the framing.
Here s what the florida building code fbc residential edition says about it.
You should then measure a small hole in the ceiling to fit the dryer vent into.
Be careful you don t cut through any studs electrical wires or pipes in the process.
If the measurements are correct then the hole should sit 4 to 5 inches from the wall where the dryer is.
If you find that it is not you can adjust it.
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.
Support the ductwork adequately to maintain this pitch don t allow the ductwork to sag in the middle.
The international residential code allows you to run a dryer vent through the attic but you can t terminate it there.