Take a Moisture Assessment of Your Home
When it comes to battling mold, the best action is prevention. If you can prevent problems from occurring in the first place, you'll save loads of money in the long run. Controlling moisture is the key.
There are essentially two types of moisture: vaporous (humidity) or bulk water from sources such as rain and leaking pipes. Moisture from either source can cause mold.
Check your grade
The first place to check for moisture is the ground near your home. The ground slope is easy to see, but to be sure the moisture is going away from — and not toward — your home, pour a bucket of water near the foundation. If the water moves toward your home, you could have a problem.
Solution: Do some landscaping. Bring a little topsoil to the area and build up the earth a little bit to create a more positive slope "away" from the house foundation.
If you have a deck behind your house, it could be hiding a low slope. Be sure to check underneath the deck to see if rain has come through and pooled in the area. Repeat the bucket test here as well.
Check your gutter system
Properly maintained gutters carry water away from the house. Check the gutters and downspouts every fall and spring (twice a year) to ensure they're moving water away properly. If the end of the downspout can't carry the water at least a few feet from the foundation, add an attachment, which can be found at any hardware store.
Maintain a dry basement
Ascertain that any drainage system is working properly. For example, if you have an air-conditioning unit in the basement, be sure it's tilted toward the direction of the drain. Same goes with a humidifier or dehumidifier. If the units aren't tilted properly, puddles can form, which in turn can cause mold to form.
Check for moisture that could be leaking in from the outside. Seal open cracks. In the basement, note that concrete can allow water to move through from wet soil outside. The surface can become damp enough to allow mold to grow.
Solution: It's hard to keep moisture from entering basement walls and slabs, so experts warn against placing mold-friendly products such as drywall and wood in direct contact with the foundation. Because basements can get humid, it's best to use a dehumidifier during warmer months.
Maintain your bathroom
Bathrooms are another major source of humidity in any house, due to steam from baths and showers. Liquid moisture in the bathroom is a problem as well. This is where the shower and tub come into play. Often it's easy for seals to go bad or for things not to drain as properly as they should. The problem can become so bad that the whole floor has to be removed and replaced because the structure of the floor is eaten up by mold.
Solution: Make sure your tub and shower are sealed properly. Replace worn caulk around the edge of the tub or shower. If there's no vent to the outside, install one.
Maintain the HVAC
Finally, be sure that your heating or air-conditioning unit drains properly into a safety pan. These units can generate moisture from the cooling or heating coils.