Ducting: A fan extracts air from the room through the ductwork. When a fan removes the air from a room, it has to then transport it through the ducting and expels it to the outside of the house through a vent. Using the correct duct length is critical for a quiet operation. The ductwork also should be as straight as possible as hard turns or multiple turns will all increase the air pressure and the noise that the fan makes. Mounting: A well mounted exhaust fan makes for a good installation. Poor mounting could also be the cause for a loud fan. When a fan is loosely mounted, the wall/window/ceiling will not be able to contain the vibration caused by the motor resulting in the entire fan assembly to move which creates excess noise. The vibration also transfers to the walls, window or the ceiling multiplying the amount of noise it makes. Will comply with Building Regulation Parts F and L if installed in accordance with the manufacturer's instructions and by a competent person. The constant drone of a noisy extractor fan can be a real nuisance. A loud extractor fan can be caused by many things: