Preventing Bathroom Mildew with a Fan
A bathroom fan is really the very best solution to bathroom mildew if you can do it. The right fan, properly installed, will do wonders to eliminate the moisture that mold and mildew thrive in. Choosing a Bathroom Fan
There are several criteria for choosing the right bathroom fan. Some are important for moisture control, others less so.
1. Noise level
This has nothing to do with moisture control, but is somewhat important. Noise level of fans are rated as 'Somes' 0-4. Anything below level one should not be louder than the sound of your fridge humming. Once you get to level three - it's the noise level of the average office, not terrible, but you probably won't hear anything going on outside the bathroom. At four - it's the same as the volume on the average TV - too loud for a small space. most people recommend 1 some or lower as a comfortable level.
2. Cubic Feet per Minute(CFM) of air movement
This is the single most important feature of a bathroom fan - how much air it can move in a minute. The Home Ventilation Institute recommends a fan that can change the air in your bathroom eight times each minute while it is turned on.
You can calculate the fan you need with the following formulae:
a. 1 CFM per square foot for rooms up to 100sq ft with standard 8-ft ceilings, but a minimum of 50CFM.
b. Rooms larger than 100sq ft - add up the CFM requirements for each of the fixtures:
Toilet - 50 CFM
c. volume of the bathroom(h*w*d) divided by 7.5, still respecting the minimum of 50CFM. For example, a 7 by 9 bathroom with 10 foot ceilings has a volume of 630 cubic feet. Divided by 7.5 gives 84 - so the fan needs to be rated higher than 84 CFM.
3. Integrated light
This has nothing to do with bathroom mildew ccontrol, and is really a completely aesthetic choice - get what you want!
4. Integrated heat lamp
This is not directly related to moisture control, and is a very nice luxury item if you would like to spend the money, or if you have poor heating in the bathroom. That being said - a good heat lamp will help a little with drying out the room.
Venting should always go outside. Venting the fan into a wall, crawlspace or attic will give you a much bigger problem than not having a fan at all. The warm moisture in the walls/attic will create the perfect growing environment for molds that can be serious health threats, spread through your entire house behind the drywall, and affect the integrity of the structure of your home.
6. Switch or Timer
If you can afford to put in a timer - do it. There are at least two good reasons. One - for moisture removal it's a good idea for the fan to run for 15-20 minutes after you get out of the bathroom. A timer means you don't have to remember to go back and turn it off. Two - with fans being as quiet as they are, sometimes it's hard to even hear them, so a timer makes sure that they shut off.