There are two main causes of damp conditions in cellars and basements.
(1) Ground and or surface water infiltration through porous walls or floors. This condition can be remedied by the techniques outlined on the previous page.
(2) Condensation. When air that contains water (humidity) is cooled, the water vapor will condense into fluid water. Cellars and basements are typically cooler than other locations in a house and thus have a natural tendency to be damp due to this phenomenon. The best water proofing in the world cannot effect this condition. There however, are three things that can individually or in combination eliminate the condensation problem.
(a) Maintain the air temperature in the basement at the same temperature as the rest of the house.
(b) Increase ventilation rate of the basement.
(c) Dry the air contained in the basement with a dehumidifier.
Choice (c) is the most commonly employed method to tackle the condensation problem. There are numerous dehumidifiers on the market that can sense a predetermined humidity level and automatically switch on and dry the air. The resultant condensed water can be automatically drained to the under floor drainage system thus allowing for unattended dehumidifier operation.