It's also a bad idea to use an existing roof vent for bathroom exhaust. You'll partially block the vent with the duct pipe, ...

Roof vents and ventilators are used to ventilate the attic or crawlspace of a building, circulating air for cooling, and moisture mitigation. More elaborate HVAC systems can use roof vents to ...

If you have two bathrooms that are close together and one has an exhaust fan and the other doesn't, you might be wondering if ...