This old house general contractor tom silva shows how to properly install a roof mounted bath fan vent.
Installing exhaust fan in bathroom through roof.
Start in the attic and drill a hole through the roof in the desired vent location.
Wrap the joints with duct tape.
See below for a shopping list and tools subscribe.
Attach the bathroom fan to the joist.
Cut a piece of drywall to make the ceiling hole the right size for your fan.
Slide clamps over the flexible duct at both the roof cap and the fan housing then slip the clamps over the tailpieces.
Leave the drill bit sticking through the roof so you can find the hole.
If the hole is too big you ll need to patch the ceiling.
The patched areas can be repaired with spackling later.
Try to keep it close to the fan location.
From up on the roof use a jigsaw or reciprocating saw to cut a 4 in.
Access the attic and bring your light cordless drill screws and bathroom fan housing.