What Causes Basement Flooding? 7 Reasons for a Soggy Basement

Walking down your basement stairs after heavy rainfall only to find it flooded is every homeowner’s nightmare. Basement flooding can be a time-consuming and expensive repair, and over time, it can cause structural damage to the home. But heavy rain isn’t the only potential cause of a basement flood. This guide explains what causes basement flooding, from poor grading to a broken sump pump.

1. Plumbing Leaks

Sometimes, a flooded basement is caused by plumbing leaks. This is more likely to be the cause if you have a washing machine or bathroom installed in your basement; however, a leak from elsewhere in the house could also cause a basement flood due to gravity.

The Solution

If you suspect a plumbing leak, turn off the water main to prevent further damage. Then, look for the source of the water to determine the next steps. If it’s a leaking appliance, you’ll need to repair or replace it. Leaking pipes will likely need a local plumber to identify the source and perform the repair. Pipe repair costs an average of $500.

2. Hydrostatic Pressure

Because basements are built below the ground, they’re susceptible to leaks caused by hydrostatic pressure from standing groundwater. Standing groundwater can put pressure on the exterior walls of your basement. If your basement isn’t adequately sealed or you have cracks in the walls, this can lead to leaks.

The Solution

The fix for this problem depends on the exact cause of the hydrostatic pressure. If it’s caused by poor drainage, call a foundation drain installation expert near you for advice. A landscaping pro can help if the pressure is caused by improper yard grading.

3. Clogged Gutters

You might not think of your gutters as the culprit, but if they’re clogged, they can cause water to leak into your basement. That’s because clogged gutters will overflow, directing water down to your home’s foundation. Even if your basement is well-sealed, it may not be able to withstand the pressure of a sudden influx of water.

The Solution

Clean out your gutters regularly—at least once a year, but ideally twice. You may be able to do this yourself with the right equipment, but it’s often best to hire a gutter cleaning pro near you to ensure the job is done safely. Professional gutter cleaning costs $120 to $235. 

4. Improper Grading

If your yard slopes toward your foundation rather than away from it, your basement is more likely to experience flooding. Yards should be sloped away from the home to allow water to drain away and prevent foundation issues, such as a leaking basement or a significant structural problem.

The Solution

Hire a local landscape grading professional to adjust the slope of your yard. This project can be a significant undertaking that requires heavy machinery and an experienced team to ensure it’s completed correctly. Leveling a yard costs between $1,030 and $3,340.

5. Sewer Backup

In some cases, basement flooding can be caused by a sewer backup. Backups occur when the sewer system is overwhelmed, such as during a heavy rainstorm, or if there’s a clog in the system. A sewer backup can also happen if tree roots, grease, or waste block your home’s sewer pipes.

The Solution

Sewer problems are best left to a sewer pro near you who understands how the system works and how to fix the issue correctly. Sewer line replacement costs $1,400 to $5,325 on average. 

6. Improper Foundation Sealing

When a home is first constructed, the builders should seal the foundation adequately to prevent leaks or to fix a leaky basement. However, this seal can wear down, causing water leaks or flooding. Older homes may not have had their basements sealed, leaving them more vulnerable to leaks.

The Solution

Check your basement’s interior walls for cracks, and apply sealant if you find any. You can also hire a basement waterproofing company near you to inspect and seal your basement as needed. If moisture has damaged your foundation, expect to pay around $5,000 in foundation repair costs.

7. Broken Sump Pump

Many basements have sump pumps installed to help remove excess groundwater from around your foundation. If your sump pump breaks, your basement is more likely to flood. 

The Solution

Check your sump pump to see if it’s functioning properly. If it’s not, call a local sump pump repair professional to inspect the system and determine whether it can be repaired or needs to be replaced instead. Sump pump replacement costs an average of $525. 

When to Call a Pro

A minor basement leak after heavy rainfall may not need the help of a pro to resolve. However, you should take even small basement leaks seriously because they could lead to more significant flooding in the future.

If you’re concerned about your basement’s water resistance or notice large cracks on the foundation walls, a local basement waterproofing expert can determine the issue and recommend the proper fix to keep your basement watertight moving forward.