Are Vents Necessary for a Finished Basement?

Basement Ventilation

• Ventilation is always necessary in practically every room of the home, whether the room is finished or has not yet been built. The basement should figure into any home ventilation strategy, because removing stagnant air and replacing it with fresh air from the outside can go a long way in preventing moisture problems that are frustrating and expensive to repair. Homeowners can forgo basement ventilation altogether, but doing so puts them at risk of problems such as mold and mildew growth, wood rotting and other potentially serious problems. Given the relatively low cost of installing vents, it is almost never a good idea not to install them in your basement.

Ventilation Strategy

• The goal of a good ventilation strategy is to achieve an ideal air exchange rate -- the process by which stagnant, indoor air is removed and replaced with fresh air drawn from the outside. There are several ways of achieving this air exchange rate, including natural ventilation, whole-house ventilation and "spot" ventilation targeted at specific areas that are prone to excess moisture. Of course, if you have not yet built your basement, you will have more ventilation options available to you. But if your basement is already finished, you will need to use a combination of all three to achieve good air circulation.

Components

• Natural ventilation includes opening windows and using ceiling fans and box fans to move air throughout the basement. If there are no windows in your finished basement, the only natural ventilation option available to you might be using box fans. Whole-house ventilation usually involves using the whole-house fan setting on your central air conditioner, an option that is conditional on whether air conditioning duct work was included in your basement. Spot ventilation includes the use of small exhaust fans and vents installed at strategic areas in the basement to ventilate air out and draw in fresh air.

Other Considerations

• Air exchange rate can actually be measured in numerical terms, called air changes per hour. Alternatively, ventilation can be measured in terms of cubic feet of air per person per hour. If you are particularly concerned about moisture and air circulation problems in your basement, and if none of the previous strategies succeeds in achieving a good air exchange air rate, consult a local contractor who can measure the air exchange rate in your basement to see if it needs additional ventilation.