Problems with Basement Condensation? Things to Consider


January 28, 2024 - DMC Residential Inspection Service Inc.


Condensation in basements is a common problem that many homeowners have to deal with. If you have this problem, it can often lead to mold growth, odours and, if left uncorrected, create potential areas for wood rot that can affect the structural integrity of your home. If you are sure it is not a water leak and have condensation problems in your basement, here are some things you need to consider to help manage this problem.


For condensation to occur, there must be high humidity levels in the home and cooler surfaces for the humidity to condense on. These factors come together usually in the basement. Basements are cooler by nature, which makes it a perfect environment for warm moist air to release its moisture when it finds its way into this cooler environment. Any cool surfaces such as walls, floors and windows can be problem areas if the temperature is below the dew point temperature of the home (the point at which water will condense on to its surface). 


As an example, during a recent home inspection the basement window wells were found to have considerable condensation present. It was winter time, the window wells were not finished and still had exposed foundation concrete that was not covered with insulation and vapour barrier. When the surface temperature was measured, it was quite cold at approximately 5 C.  After calcuation of the Dew Point in the home it showed that water would condense onto surfaces at or below 10.5 C.  The exposed wall temperature was well below 10.5 C and was creating a problem by providing a surface area where moisture in the air could condense to water and pool in the window sill. If not addressed this would eventually become a much larger problem. This is why it is so important to ensure when finishing basements, these cooler surfaces are covered with insulation and vapour barrier.


Another key area for consideration is ensuring your home is adequately ventilated to help with controlling of humidity levels. Without proper air circulation in the home, moisture in the air can accumulate and create an environment for the condensation of water to occur. In the case of the recent inspection, an unsealed conduit was discovered to be letting cool moist air into the basement. This was adding to the humidity levels in the home and making it much harder for the ventilation system to do what it was designed to do and help control the environment.


Water leaks and moisture intrusion can also become common problems in basements. Cracks in the foundation, poorly sealed windows, damaged pipes or unsealed conduits can allow water to enter, adding to the overall moisture content in the basement air. This can significantly contribute to condensation issues. It is important to seal any cracks, or gaps in the foundation and ensure outside air is not finding its way into your home environment when you don’t want it to.


Another way to help alleviate condensation in the basement is through investing in a high-quality dehumidifier. Choosing a dehumidifier with the capacity to handle the size of your basement and has a continuous drainage flow is key considerations when purchasing. Health Canada has provided that home humidity levels are generally best kept below 50% in summer and between 30-35% in the winter. [1]


Increasing air flow in the home is important. Sometimes we can open windows when weather permits. However, when the weather doesn’t cooperate, mechanical ventilation, such as a heat recovery ventilation system, can help ensure fresh air is brought into the home while exchanging it with the stale, humid air in the home.


Other considerations such as applying water proof coatings on foundations if you are living in an area with a high-water table, or installing a sump pump, ensuring down spouts drain away from the house up to 6 feet, and that grading around the house slopes away from the house at least 6 inches every 10 feet are important to help keep water from pooling near your foundation and seeping into the basement.


Condensation can be a major headache for home owners, but knowing what you are are dealing with and how to address the problem proactively, can help you manage the issue effectively. By improving ventilation, better controlling humidity levels, insulating, waterproofing and sealing, using vapour barriers and practicing regular maintenance, you can create a much more comfortable living space and healthier environment. Controlling condensation in the home not only preserves the structural integrity of your home for years to come, but also improves the quality of life for you and your family.