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Flooded Crawl Space? 5 Common Causes and Their Tell-Tale Signs

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Your crawl space is likely an area in your home that you don't frequently visit. In fact, it's relatively remote. But if water tends to pool under your house it can become a dangerous health issue. These types of unexpected problems are not only annoying, they can also develop into a much larger problem such as a flooded crawl space.

Cleaning and repairing a flooded crawl space costs average $6,000, and could be as high as $15,000! So clearly a little prevention can go a long ways. And even if your crawl space doesn't totally flood, it could become a breeding ground for mold. Mold needs two things to survive: Moisture and darkness, and crawl spaces provide both of these two requirements.

Where's the Water Coming From?

Determining where the water in your crawl space is coming from is the first step to fixing the issue. There are two possible options:

Above Ground

If the water in your crawl space appears to be coming from above ground, it's likely caused by a drain pipe or a leaking water supply pipe. An easy way to check is if you notice the water level increases in the crawl space when your water is running inside the house.

For example, the dishwasher or washing machine is running, a toilet flushes, or someone is taking a shower. If the water level in your crawl space goes up, the problem is most likely caused by your household plumbing.

Below Ground

If the water in your crawl space seems to be coming from nowhere, then there's a good chance that its seeping up through the ground or through the walls of the foundation.

Water Damage or Flooded Crawl Space: 5 Common Causes

Whether you have ground water in your crawl space or your water is coming from your home's plumbing, these are the five most common causes to crawl space flooding:

House with wheel barrel  hauling flowers for flower beds

Landscape Grading

All houses, new or old, with basements or with crawl spaces, should regularly check the landscape grading. We recommend doing this during the Spring after the ground thaws. This is a good time to see if the Winter weather washed away any soil.

Simply walk around the perimeter of your home and look for any areas where the soil has dipped and water is pooling next to the foundation. Although, other signs may not be so obvious, if you see pooling, it's a clear sign that there's a problem. 

You might be surprised at how easy this problem is to fix. Simply add some soil to the lower areas and you'll be able to build them back up to the necessary level.

The proper slope should be 1-inch for every foot. This will direct the water away from the walls of your foundation. The slope should extend outward for 6 to 8 feet.

This video will show you how to properly grade around your home.

Watch the Video

Man adding an extension to his gutter's down spout

Gutter and Downspout Issues

When it comes to crawl space leaks and flooding, gutters and downspouts may rank at the top of the list. During a rain storm your roof collects an amazing amount of water. If the gutters are not cleaned regularly the water has nowhere to go . . . other than over the side of the gutter. 

When gutters overflow, large pools of water frequently develops around your house, which can negatively affect the landscape grading that surrounds your foundation. The water can eventually seep into or even cause flooding in your crawl space. Gutters can only perform their intended purpose if they are kept clean and free of debris.

However, even if your gutters are clean and collecting water as they should, improperly placed downspouts can be a major issue. Water should be directed away from your house to prevent pooling.

This video will show you how to drain downspout water flow away from your house and crawl spaces.

Watch the Video

Sprinkler on Green Grass

Flower Beds

We all love beautiful landscaping, but unfortunately flowers and shrubs need to be watered. Sprinkler systems, forgotten hoses that are left running, and sometimes simply over watering, can cause pooling that can eventually find its way into your crawl space. 

Copper Pipe Burst

Broken Water Lines

Not all crawl space problems originate from outside your house. If you have an unnoticed  broken pipe inside, water will trickle down and eventually find its way to your crawl space. 

Although, this may seem unlikely, its actually more common then many people realize. Take a visual inventory of your home and look for any obvious wet spots.

If you suspect you have a broken pipe, but are unable to locate the source of the leak, call a professional plumber. They'll be able to pinpoint the exact spot and repair it for you. 

City water main burst and flooding the street

Subterranean Water

Crawl space leaks and flooding can also be caused by situations that are beyond your control. City water lines rupture, torrential storms pass through,  and the ground water table frequently reacts to these and other situations. 

In many cases city municipalities will need to diagnose and resolve the situation. If the flood was caused by a broken pipe, its normally the cities responsibly to fix the pipe if the problem occurred before  your water hook-up. However, if the problem was between the water hook-up and your home, you'll likely be responsible for it's repair. 

Subterranean water can be caused by a number of issues:

  • Clogged or damaged underground drains that were designed to carry water away from your house.
  • The drainage system is overwhelmed by a heavy storm and the overflow water is absorbed by the soil.
  • Improper drainage can create a situation where the walls of the foundation will not allow the water to pass. The walls can literally create a dam that can prevent the water from properly draining.

How to Dry Flooded Crawl Spaces

Once you've identified the source and stopped the leakage, it's time to dry your crawl space. Here are the three steps you'll need to take to do the job properly:

Step 1: Remove the Wet Material

This may seem obvious, but leaving wet materials in your crawl space will not only require more "dry-out" time, but it may also be dangerous.

Remove and discard damp fibrglass insulation. Do not try to dry it out. A simple rule, if it's wet, you should remove and discard it. This includes junk, debris and other suspect fiberglass materials.

Step 2: Remove Standing Water

portable sump pump can remove standing water in your crawl space, and in some situations you may need to use several pumps to get the job done.

Superior Pump 91330 1/3 HP Thermoplastic Submersible Utility Pump with 10-Foot Cord

Portable Sump Pump

This sump pump can be moved from one location to another as your dry your crawl space.

Step 3: Remove Moisture

Even though you've eliminated the standing water in your crawl space, the subfloor overhead, wood framing and crawl space surface itself is still wet and needs to be dried of moisture.

The best method is to use a crawl space dehumidifier and add a few fans to encourage airflow. These types of dehumidifers aren't inexpensive, so unless you have a need to own one you may want to rent a unit or hire a professional to do the job for you.

AlorAir Basement/Crawl Space Dehumidifiers Removal 120 PPD (Saturation) 55 PPD (AHAM), 5 Years Warranty, HGV Defrosting, cETL, Epoxy Coating, up to 1,300 Sq. Ft, Remote Control (optional)

Crawl Space Dehumidifier

A dehumidifier will remove the water from the air and wood surfaces in your crawl space.

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