Bathrooms with shower stalls or bathtubs require ventilation or they risk condensation and mould growth.
A bathroom fan helps to reduce moisture and odours by exhausting stale air out of the building after it passes through a filter or exhaust ducts, depending on what type is used. A bathroom fan exhausts outside to the roof vent of an apartment building using an insulated flex duct typically 6 inches in diameter. The bathroom exhaust fan and venting should be ceiling mounted in the roof space so that there is 1 cubic foot per minute of outdoor airflow for each square foot of the bathroom's floor. This is calculated as cubic feet per minute of airflow (CFM). Ventilation fans are placed in bathrooms and other spaces where there is little or no natural air circulation to help balance out humidity levels. The ventilation system also helps get rid of excess moisture by drawing stale, humid air through the bathroom vent. The setup needs to have these ducts terminate as close as possible to the roof ridge or wall closest to the ridge according to certain building codes. Fresh ventilation allows less household odours to build up as well.
Bathroom fans usually have a mounting template that provides you with an area where the exhaust opening and the fan box needs to go for the best results.
The distance away from the centre of the ceiling is not as important as making sure that there is enough scope at each end of your ducting installation so that it does not get pinched against anything when installed.
The exhaust opening for the bathroom fan may be in a roof peak or ceiling that is located above the shower area to reduce moisture from getting into the room below. Worst case scenario is having to change your showerhead if it is too close to the ceiling. The ductwork needs to be connected to the outside through an insulated, ventilated chase to the roof. The fan cannot simply terminate in an attic or crawl space because it needs to exhaust moist air that may collect below its location.Bathroom fans do not bring in fresh air from the outside. A bathroom exhaust fan is connected to ducts that connect it with the exterior so that warm, stale, humid air can be exhausted by the fan and vented out of your home. The fan itself does not move fresh air from outside into the room. To bring in fresh air into the bathroom you would need to open a window or install an air intake vent that brings in fresh air from the outside directly into your bathroom.
In addition to the moisture issues that may develop in your home, you are also risking having pest problems if you do not exhaust out humid air as soon as possible.
Exhaust fans running all day can help deal with any such issues so that your home stays clean and healthy. This helps wood rafters to stay dry that enables mould neutralisation and other similar problems.
First step of the process is to locate your attic hatch. If it's not easily accessible then you will need to install one access point on the ceiling in order to get the air ducts up into it. Once you have that location marked out then you can plan the way of your exhaust fan. It is easiest to run ductwork it from the ceiling and straight out one of the existing attic vent. You may need to cut a hole in one piece of sheet metal in order for the ducts to fit into the hole or around it if the existing vents are tight against each other.