Why Is The Humidity In Your Basement So High?
How many times have you walked into a basement and it hit you; that damp, musky smell and that clammy feeling on your skin?
The humidity is so high you can almost see the water hanging in the air. Basements that don’t have basement dehumidifiers are notorious for being damp and uncomfortable. We all know what humidity feels like, but some people may not actually know what it is or what causes it. Basically, humidity is a term that refers to the amount of water vapor in the air. Air at a specific temperature can hold a prescribed amount of moisture. The warmer the air is the more moisture it can hold. Relative humidity (RH) is more complicated to explain so we’ll tackle that subject in a future resource article.
Let’s examine some of the reasons for high basement humidity. Just the way basements are constructed makes them susceptible to humidity problems. Older homes can have unfinished basements with dirt floors that
create enormous moisture issues. If you have one of these type basements, you can reduce water vapor entering your basement by covering it with a plastic sheeting vapor barrier before installing a basement dehumidifier. Without the plastic vapor barrier, a more powerful dehumidifier is required. Most modern home construction basements are built with little concern for air circulation, which just adds to the problem of controlling moisture. If you do laundry in your basement, the washer and clothes dryer is also contributing to humidity levels. Make sure that your dryer is vented outside and that the duct is securely attached to the dryer. Sealing any air leaks in basement windows and doors will also help reduce humidity.
Basement humidity is caused primarily by these 5 sources:
- Infiltration of outdoor humid air
- Vapor transfer from soil moisture
- Water entry
- Occupant activity
- Lack of air circulation
The problem of soil moisture entry through the foundation into the basement should not be underestimated. Water permeates porous concrete through capillary action commonly called wicking.
The University of Minnesota Extension Service estimates that as many as 100 pints of soil based moisture can enter a basement each day.
Foggy basement windows are a typical sign of high basement humidity. Often homeowners see water on windows or walls and mistakenly conclude there must be a water leak when in fact, the problem is actually condensation due to humidity. The moisture in the air of a damp, humid basement condenses on windows because the temperature of the window surface is below the dew point of the air in the basement. This excess moisture can damage the window frame, walls around the window and lead to mold growth.
Consequences of condensation include:
- Warping/wood rot
- Damp insulation
- Mildew/mold
- Drywall damage
- Blistered, peeling or discolored paint.
You may find that your ceramic tile in the basement is cold and damp. And you may ask what products can be used for damp proofing a basement? Many people ask what floor finish to use for damp basement floors, or how to deodorize a damp basement, or how to use chemicals to clean a damp moldy basement? These questions may lead to a way to address symptoms of a larger problem. Regardless of whether you have a fully finished basement or a dirt floor, the question to ask is how to go about removing humidity from a damp basement.
You can eliminate condensation by significantly lowering the humidity with a Dri-Basement dehumidifier. A damp basement is a tough environment for the average home dehumidifier. The Dri-Basement was designed specifically to solve basement humidity problems. By collecting certain information from you about your basement and home, an air quality expert known as an application engineer can calculate the specifications for equipment and make accurate dehumidifier equipment recommendations to maintain the correct humidity level for your basement.
December 20th, 2009

