As others have mentioned, spend a few bucks on a good fan. Use rigid vent pipe rather than the expandable for much greater efficiency and longer life.
Use a flapper vent to keep cold drafts out.
Use a flat bar to pop the nails on the shingles in the area where the hole will be cut and than weave the shingles back into place around the collar you install. You'll need minimal goop to seal the nail heads and around the cutout and that will do it. A laser pointer or pendulum will help you line things up.
Do not, like one dumbass I know, wire your fan to a GFI relay circuit because you'll trip it every time you hit the switch. But I never did it again.
MrBob screwed with this post 10-06-2012 at 10:17 PM