Basement Humidity: Causes and Solutions

Howard Shachter, vice president of U.S. Waterproofing, has seen water damage large and small. Here he explains the common causes and solutions to basement humidity.

Causes of Basement Humidity

High levels of humidity plague many houses’ basements. The main problem with humidity is that is causes mold to grow, which causes funny smells, black mold damage and often health problems as most people are allergic to the spores that are contained in the air.

Basements are typically the coolest part of the house. Though your upstairs air conditioning unit removes humidity, the cool humid air migrates to the basement, increasing the moisture in your basement. The problem is worsened as circulation is typically poor in basements. People usually don’t have vents to remove air and rarely open basement windows.

Sometimes humidity is caused by moisture infiltration, also known as seepage. The probable cause of seepage is when water gets trapped in the hollow concrete blocks that make up your basement walls. Many foundations and basement walls are made of hollow concrete blocks that sometimes have water slowly infiltrate into them through microscopic pores. This is not enough water to leak into the basement, but it is enough to cause humidity in your basement.

Solutions

The most simple solution to a humid basement is to buy and install a dehumidifier. The main problem with these units is that they are expensive to operate.

Cheaper consumer models are not very effective. While they can dehumidify up to a few hundred square foot area, they won’t be able to handle all the humidity in a large open basement. Some dehumidifiers are designed for larger spaces, but these cost considerably more. If your problem is only occasional humidity, a dehumidifier is the answer for many people.

A standard dehumidifier takes in humid air and compresses it. When the air is compressed, it cools. The cool air cannot carry as much moisture as warm air, so the water is removed from the air and collected. It essentially squeezes the water right out of the air and deposits it into a bin or a hose that runs into floor drain or sump pump. Dehumidifiers with bins don’t usually have a large capacity, so look for ones with a hose. Otherwise, you’ll continuously be emptying bales of water.

There are also dehumidifiers that exhaust humid basement air through a vent to the outside and replace it with conditioned air from upstairs. While these use less energy since they do not operate an air compressor, they make your air conditioning unit work harder.

How Do I Know If I Have Humidity

If your unsure your humidity is too high, you can usually feel it when breathing or rubbing your finger on your arm or look for condensation in the windows or perhaps there is a funny smell in the air from mold spores.

If you need complete confirmation, there is also a humidity measurement tool called a hygrometer. This instrument measures the relative humidity of your air. They can be purchased from specialty stores and online for less than $100. While we at U.S. Waterproofing do have hydrometers, we don’t usually take one out on a job unless it is specifically requested.