What Causes Moisture in Your Ceiling?

Lack of Humidity Control

• Certain activities performed in the home can increase the amount of moisture in the house. Mopping floors, cooking on a range without an exhaust vent, washing or drying clothes, taking a shower or bath and growing plants indoors, all create moisture in your home. To reduce moisture from cooking, use an exhaust vent and cover pots and pans when boiling foods. You should also use exhaust vents when bathing. Ensure the vents release the air outside the house, rather than in an attic or crawl space.

Lack of Circulation

• A ceiling can develop moisture problems when air does not circulate in the attic or crawl space directly above it. If there is no room in the overhead space for air to circulate and carry away moisture from the house, moisture that rises from the house is not removed and is trapped in the ceiling, showing itself as water stains. The long-term solution is to redo the crawl space or attic to allow for better circulation. In the short term, closing off all openings into the overhead space and applying a vapor retarding paint to the ceiling may mitigate the problem.

Ice Dams

• Ice dams, blocks of ice on the lower portions of a roof, can prevent water from draining off a roof and cause it to back up and stain walls or ceilings. The ice dam occurs when snow unfreezes when it falls on a warmer area of the roof, then refreezes when the water hits a colder area, such as the overhang. The best solution for ice dams is to keep the entire roof cold. You can do this by increasing the amount of and R-value (resistance to heat flow) of insulation in your attic, which will decrease the amount of warm air that escapes to your roof.