Causes of Basement Moisture and How to Fix Them

10 October 2020

 Basement moisture is a very common problem. But what causes it?

Basements are notoriously damp and dark places. Most often, moisture in a basement is nothing to worry about. In some cases, however, it can be bad news for homeowners and lead to bigger problems. 

Moisture can cause toxic mold and structural damage, as well as several other issues for you and your home. Being proactive in getting to the bottom of the causes and fixing them likely will save you time and money in the long run.

Here are some of the main causes of basement moisture and what you can do about it:

Cracks in the foundation

Water will definitely find any crack in a building’s foundation. Water will then find its way into the basement.

Various structural issues in and around the foundation may result in cracking. 

Foundation cracks can often be caused by water. This can happen if the drainage, especially in the soil, is poor. 

Water may accumulate against your foundation walls if it is not properly directed away from the foundation. The accumulation of water against the walls will cause hydrostatic pressure, forcing the water to penetrate the walls, thereby creating cracks. 

Fixing it: The solution to this problem varies based on what has caused the cracks. If the cracks are as a result of hydrostatic pressure, then you should simply repair the exterior drainage. If the cracks are due to structural problems, you should seal the gaps by putting into place proper connections and footing. This can be advanced work and may require the assistance of a professional foundation repair contractor.

Interior water leak

When you are trying to determine the cause of basement moisture, you should start by checking for any inside leaks. A water leak may come from bad pipes, showers, dishwashers, washing machines, sinks, toilets, and so on. 

In most cases, if you locate the moisture on your basement ceiling or on the walls beneath the kitchen or bathroom, then the problem can be attributed to an interior water leak. Identify the exact location of the moisture and find if there is anything that is leaking in that area. 

Fixing it: Solving an interior leak problem is usually very easy. Repairing the leak will solve such a problem. If you cannot make the repair yourself, hire a local plumber to fix it for you. 

Defective or missing downspouts and gutters

Downspouts and gutters have one main purpose – directing the rainwater a predetermined direction away from your home’s foundation. If those downspouts and gutters are not functioning well, or if they are missing, rainwater is likely to move towards and into your home. 

As water continues to drain toward your home, it will accumulate in the surrounding soil. If water that is accumulated around the foundation stays there, it will eventually find its way into the basement causing moisture.

Fixing it: If there are no gutters in place, consider adding them. For every 50 feet of your roof eave, place at least one downspout. Place extenders on every downspout to disperse water four feet or further away from your foundation. Clean existing gutters on a regular basis to ensure that they are functional at all times.

Ineffective grading

Groundwater or rainwater often finds its way into our basements if grading is poor. The ground around the foundation should be sloping away from your house. 

If the flow is towards your house, water will start accumulating against the foundation and will eventually find its way inside. 

This usually happens if the fill dirt around the foundation is not is not compacted properly. The slope will change as the dirt settles. With time, water will start flowing towards the house instead of flowing away. 

Fixing it: This problem can be fixed by building up the dirt around the foundation and creating a slope that aims away from your house. The slope should lower by one inch or more per foot.

Missing or poor sump pit or drain tile

Many houses lack subsurface drainage systems. Years back, there was no need for under-the-floor drainage systems because basements in those older homes were often not to be spaces to live in. 

Some modern homes with under-the-floor drainage systems tend to experience problems especially with their system. These problems may include broken sump pumps, damaged connections, or clogged pipes. 

Fixing it: Repairing subsurface drainage system issues tend to be more serious projects that require the help of a professional. Call in help to add a functional drain system that leads to a pump that will expel any moisture from the home. Repairing or building subsurface drainage systems should be done by experts because it is a complex task.  


Condensation can also cause basement moisture. Basement condensation typically occurs when moist, warm air comes into contact with the cool basement floor and walls. As the warm air gets cooled, moisture is usually created.

Fixing it: Basement moisture caused by condensation is often easy to fix. There are more than a few effective ways of dealing with basement condensation. Start by checking your dryer’s exhaust. If you have one, drain your central air conditioner and ensure that it is not clogged. 

You may consider installing an exhaust fan if there is a kitchen or bathroom in the basement. Whenever you use the stove or take a shower, you should use that fan. 

Also, consider increasing air circulation. Add air conditioner vents or a dehumidifier that runs at least a few hours every day.


Basement moisture problems range in nature to simple causes that can be repaired easily to complex structural issues, including bowing, sinking and cracking. While most are minor, it is wise to consult a professional when faced with advanced issues.