Indoor Relative Humidity

Relative humidity is basically just the measurement of water present in the air. If the relative humidity measures at 100%, it indicates the air is heavily saturated with water vapors, with a good chance of incoming rain. These levels vary according to temperature: warmer air can hold more water, thus a reading of 50% during a hot summer day means something different from 50% in a colder climate. 

When it comes to your basement, if the outside air is warm and it gets into your home and then cools, it directly affects the relative humidity inside your home. For every degree cooler that your temperature is changed, the relative humidity increases by 2.2% per degree cooled.

Depending on the outside humidity level and temperatures, this can cause a variety of problems. For example, if it’s 80° outside with a humidity level reaching 65%, and the air enters your basement and cools down to about 65° in your basement, the relative humidity can reach up to 98%. Considering the fact that mold can grow when relative humidity levels reach 70%, this poses a significant risk. Not to mention, condensation begins to form as soon as the air reaches your cold water pipes, unfinished walls and other cold basement surfaces.

Regardless if there is any condensation present or not, relative humidity levels will unfortunately remain high, allowing mold and mildew to develop and create foul odors for your basement.