Venting Exhaust Fans Through the Roof (DIY) - Family Handyman Start in the attic and drill a hole through the roof in the desired vent location. Try to keep it close to the fan location. Leave the drill bit sticking through the roof so you can find the hole. From up on the roof, use a jigsaw or reciprocating saw to cut a 4-in. round hole. Next, measure out a square slightly larger than the protruding part ...