Six Common Causes of Basement Moisture

Have a damp basement? Basement moisture is not uncommon. Basements are known for being dark and damp. Despite being a common problem, basement moisture can cause serious problems. A little water in a basement can cause severe problems for homeowners. Basement leaking can lead to significant issues for your home, including structural damage and toxic mold that can be dangerous to your health. What are the causes of basement water? What can you do about it?

Let’s start at the beginning. How do you determine if your basement is leaking? It is crucial to recognize the symptoms and signs of what causes moisture in your basement. Basement moisture signs may not be obvious, like a puddle on the floor. There are many ways that moisture could be present in your basement. Here are some things you should look out for:

  • Water trickling out of the walls
  • Saturated Concrete Walls: A Ring of Dampness
  • Condensation on Walls and Floors
  • Walls that are stained or blistering
  • Damp and humid air
  • Standing water on the floor
  • Carpet and wood that is deteriorating
  • Rotting Columns, Headers, and Joists
  • Odors of Mold and Mildew

These signs are indicative of leaking in your basement. Let’s now find out what is causing the moisture.

A wet basement is usually from one of three sources.

  1. Rain or groundwater This is water from the outside that finds its way into your home. For example, a mere 1 inch of rain can pour 1,250 gallons of water onto a 2,000 square foot home. This water could get into your basement if you don’t have proper grading, gutters, or downspouts.
  2. Interior Moisture Sources Sometimes, water from our basements is created or originated there. These sources include showers, drying, cooking, humidifiers, and moisture from newly-constructed concrete.
  3. Ventilation with Humidity, Outside Air We open basement windows in warmer weather to allow airflow. But, humid outside air can condense and cause damage to the basement walls and floors if allowed into the basement.

Knowing where water comes from can help us determine the source of the problem and what we can do to solve it. Take a look at our list of:

How to solve basement moisture problems: 6 common causes


1. An Interior Water Leak

Although this may seem obvious, you should check for any inside leaks before trying to find the source of moisture in your basement. Water leaks can occur from many places, including a faucet, a toilet, or a sink. It could be an interior water leak if moisture is found in your basement, such as on ceilings or walls below a bathroom or kitchen area. Determine where the water is coming from and if there is any leakage.

How to fix it: A typical interior leak is one of the easiest to fix. You can repair the leak or have a plumber do it. The moisture will then be gone.

2. Ineffective Grading

Poor grading can lead to groundwater and rainwater getting into basements. Your foundation’s ground should slope away from your house and not in its direction. Water that drains in the wrong direction can build up and cause damage to your foundation. This is often caused by poor compacting of the fill dirt around your foundation. The slope of the dirt will change, and water will flow towards your house instead of away.

How to fix it: Start by building up dirt around the foundation and creating a slope that points away from your house.

3. Missing or defective gutters and downspouts

Gutter and downspouts are designed to divert rainwater away from your foundation. Rainwater can flow towards your foundation if gutters or downspouts fail to function properly. Rainwater can collect in the soil surrounding your house as it drains towards it. Water that accumulates around your foundation will most likely make its way into your basement.

How to fix it: If gutters are not in place, you might consider adding them. One downspout should be installed for every 50 feet eave on the roof. All downspouts should have extenders, which disperse water at least 4 feet away from the foundation. To ensure that gutters are working properly, they should be cleaned frequently.

4. Cracks in Your Foundation

Water will seep into basements if there are cracks in the foundation. Sometimes, the water can even be the reason for cracks. It can cause cracks if floor joists don’t connect properly to foundation walls. Poor drainage can also cause cracks in foundations.

Water that isn’t directed away from the foundation can build up against the foundation walls. This pressure (hydrostatic pressure) can cause water to enter walls and create cracks. No matter how cracks were formed, water can still get into your basement through them.

The Solution: Your options will depend on the root cause of the cracks. Hydrostatic pressure, which is caused by water accumulating around the foundation, can cause cracks. If this is the case, you should repair your exterior drainage. While cracks can still be repaired, the root cause of the problem should have been addressed. Proper footing and connections (straps, anchor bolts) should also be installed if structural problems are to blame for cracks.

5. Improper Drainage

Many houses don’t have a subsurface drainage system. Many basements in older homes were not meant to be habitable, and therefore an under-the-floor drainage system was unnecessary. Modern homes with a drainage system are less likely to have problems. Drainage issues can also be caused by a blocked pipe, a broken connection, or a damaged sump pump.

How to Fix it: Subsurface drainage problems or adding a new system is more complex than other waterproofing issues. It is best to contact professionals if you suspect this is the problem. The solution involves removing your flooring and installing a drain system that will allow for a sump pump to expel moisture. Experts with the right tools and knowledge are best to build or repair a subsurface drainage system.

6. Condensation

Basement condensation is when moist, warm air touches your basement floor and walls. The walls cool the warm air, and moisture is formed. It’s similar to condensation from a cold drink on hot summer days. If your basement has moisture from condensation rather than a drainage or leak problem, you’re in luck. These issues are usually much simpler and cheaper to fix.

How to Fix it: There are several ways to fix condensation in your basement. Check the exhaust from your dryer first and then drain the central air conditioner. Check that they aren’t blocked and that they are working correctly. They can also cause an unusual amount of moisture to be released into the air.

The next step is to consider the following:

  • Basement exhaust fan: Installing an exhaust fan in your basement bathroom or kitchen is a must. Condensation can be caused by steam from hot showers or cooking. Make sure you turn on the exhaust fan when you take a shower or use the stove.
  • Increase air circulation: If there is only a small amount of condensation, you can increase your air circulation to resolve it. Consider adding air conditioning vents to your basement if it does not already have any. This is usually a simple project. To keep the air moving, make sure you keep your vents open. A fan can be used to circulate moisture if you don’t have AC. Air will flow better if your basement is less cluttered.
  • Insulate your Basement: It is possible to reduce moisture by insulating areas where condensation has built up. Insulating walls, pipes, and ducts will prevent warm air from coming into contact with cool surfaces.

Warning signs for moisture

Do not delay in taking action if you notice signs of moisture in your basement. The more the problem continues, the more expensive and extensive the repairs will become.


The SANI-TRED System eliminates basement moisture and its accompanying problems at the source. It has been trusted by over 100,000 DIY customers.

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