Proper ventilation in a bathroom is extremely important. The majority of bathrooms are quite small and it does not take long for them to steam up and smell. If you were to dye your hair in the bathroom it will be difficult to rid the room of the smell of the chemicals used, it is absolutely necessary to have bath ventilation fans installed. Because of the dampness that is found in a bathroom, it does not take much for mold to start either.
Not every bath is located in such a position in the house that it can have a window however those bathrooms that do have a window can draw in fresh air which is very helpful, unfortunately this can be a real problem during the winter months when the outside temperature is below zero.
In most cases, window or not and irrespective of the baths location in the house most people install bath ventilation fans. These fans draw air from inside the room, including odors and moisture and exhaust this foul air outside the building. This is seen as a great solution and you don’t have to worry about freezing if the window is not opened. In most jurisdictions it is mandatory to have a vent or a fan installed for bathroom ventilation, the most effective are bathroom exhaust fans.
In many cases the bath vent fan operates from the same wall switch that turns the bathroom light on and off however there are units available that have variable speeds and they are operated from a separate rotary switch. As it is not necessary to activate the fan every time a person enters the bath it can be a power saver if the fan operates from a separate switch. If you simply go into the bathroom to wash your hands all you really need is light, the fan is not a necessity. There are also situations where the bathroom light will be turned on to cast light in a dark hallway; once again there is no need for the fan.
An exhaust fan must be sized properly for it to be effective. The rule of thumb that is used in sizing the fan is one CFM (cubic feet per minute) for every square foot of bathroom floor. A 40 square floor bathroom will require a ventilation fan rated at 40 CFM or higher.
