Recognizing and Controlling Moisture Buildup in the Home

When warm air from the tropics encounters a cold front, the results are often thunderstorms. When warm moist air from indoors makes its way into cooler walls and attic spaces, the result is condensation which leads to mold, rot and rust. And there is no time when this is more prevalent than early spring.

While everyone talks about the weather and can do nothing about it, moisture in homes can be controlled. The way to deal with it is to determine if there is a problem, understand where it comes from and then learn to control it.

Where Moisture in Homes Originates

Typically, moisture in the form of excess humidity is produced in homes just by the act of living in them. Taking a shower, cooking a meal, even breathing all add moisture to indoor air. You don’t necessarily need a leaky roof or seepage from masonry surfaces to create excess humidity, although they will certainly contribute to the problem.

When moist inside air contacts cold exterior surfaces the moisture in the air condenses to form water. Once this water is released from the air it can do its damage. For example, if a bathroom fan exhausts warm moist into the attic (instead of outside as it should) the air will mix with the cold air in the attic. When this happens the moisture in the air will either condense on attic surfaces or worse, create its own mini weather system complete with a small rain shower in your attic.

To a lesser degree this same effect can happen in exterior walls, around single pane windows, on the side of a refrigerator or anywhere inside air meets the cold outside air.

Symptoms of Moisture Problems

If you suspect moisture problems look for the following signs:

  • mold, fungus or mildew on interior surfaces
  • efflorescence (salt deposits) on both interior and exterior surfaces
  • flaking paint and peeling wallpaper
  • corrosion on metal surfaces including metal surfaces in basements and attics
  • condensation on windows and walls
  • warped, cracked, or rotted wood
  • chipped or cracked masonry surfaces
  • ice dams in gutters and on roofs
  • dank and musty smells

Controlling Moisture

The best way to control excess humidity is to stop it at its source.

  • Fix all leaks, roofs, pipes and radiators.
  • Control seepage through masonry by applying waterproofing treatments.
  • Keep moist air away from cold surfaces by plugging holes in walls and sealing fixtures and outlets.
  • Seal leaks in ventilation systems.
  • Make sure that exhaust fans, such as those in bathrooms and kitchens, vent outside.
  • Consider upgrading poorly insulated windows and doors.
  • Adjust your heating system to take in at least 10 percent of its air from outside. This will improve indoor air quality.
  • Turn on fans and open windows when showering or cooking.

Treating Moisture Damage

Finally, once excess humidity is under control, it is important to treat and repair all moisture damage promptly. Moldy areas should be scraped clean and washed with bleach. In most cases, damaged wood should be removed because rot will often continue even after the source of water has been removed.

Don’t delay repairs. Spores from mold and other fungi can be released into the air and can lead to various respiratory illnesses.

To determine whether you have solved your moisture problems, you may want to test with a moisture meter or have a professional tester check for you. Inserting the moisture meter probes into plaster, wood or other building materials lets you test in areas you cannot see. If the levels are too high, then you have a problem. If not, then you can rest easy.