How to Stop Basement Water Leaks

Water leaks in a basement are almost always the result of poor site drainage around the house and from roof drainage not properly being handled. Basement leaks often occur during heavy rainfall events where the amount of drainage water overcomes the ability of the perimeter drains and sump pump around the basement walls. There are some very correctable ways to achieve better drainage to stop basement water leaks. Try following the steps to identify possible issues with your site drainage to be able eliminate water leaks into a basement.

Things You'll Need

• String line level
• Downspout extensions

Instructions

1. Check the existing site grades around the house. The grades must be designed to allow water to quickly flow away from the house in every direction a minimum of 25 feet. Use a string line level to verify the grades around the perimeter of the house. To do this get a piece of sturdy string about 10' long. Tie each end of the string to a wooden stake that can be driven in the ground. The tied ends of the string should be a loop so the string can be slid up and down on the stakes. Drive one stake near the house and the second stake away from the house. The stakes should be driven so the string is very tight with no sag in the middle. Place the line level in the middle of the string and slide the strings up or down on the stakes to "level" the sting line level with the bubble in the center of the two lines on the level. Measure the distance from the ground to the line level near the house (H1) and away from the house (H2). Measure the distance between the stakes (X). To calculate the grade use the following calculation:

   (H2-H1)/X (all units must be the same such as inches or feet)
   Multiply the result by 100 to get the grade in the form of a percentage.

   The site grading should allow drainage to flow towards the street, ditches, or to open water storage areas such as a pond, lake, river, or stream. The grades near the house should be at least 1/4" fall per foot or just over a 2% grade.

2. Inspect the topography around the basement area. In particular, look for stagnant locations of surface water near the basement such as swimming pools, ponds, lakes, sinkholes, swamps, or ditches with no water flow. If there are hills or mountains nearby, water will also collect in these areas and through gravity move to a lower elevation. If surface water is allowed to pond near the basement, it is likely to become ground water. Since the level of the basement is lower than the surface water it is likely travel to this location since basement perimeter drains are easier for water to travel through than soil and bedrock. If surface drainage is traveling to a basement, either try to divert the water on the surface by installing new ditches that promote flow away from the basement or place an underground French drain to collect the water and divert it away from the basement.

3. Find out more information about local underground water also known as ground water. Talk to local officials and engineers who have public information that can be requested regarding the ground water in your area. Check with your local or State department of natural resources or the local sanitation department that approves septic systems and ask for well records near your home. Depending on the state, City or County Engineer's have jurisdiction over local drainage and water flow. Good information to obtain is on existing well records, soil boring records, storm sewer pipes, septic lines, sewer lines, and water lines. All these records may contain information about groundwater conditions or potential ground water. If you believe there is a leak in a sanitary or storm sewer line call the city, county or township engineering office and notify them there is a possible leak. They can test the lines either through video detection or using dyes.

4. Carefully Inspect the gutters and downspouts around the roof of the entire house. Drainage must flow freely into the gutters, travel down the downspouts, exit the downspouts, and flow away from the perimeter of the house. Extend downspouts at least 4' to 8' away from the perimeter of the house. It is very common to see basement water issues directly cause from downspouts too close to the house. If water problems are occurring during or right after a large rainfall event, then carefully look at the path of the water exiting the downspouts.

   Keep the gutters and downspouts clean and free flowing at all times. The Fall is critical to keeping gutters clean since leaves will clog the gutters and ice can form. Melt water and rainfall will then flow directly over the gutters near the house. This typically occurs in early spring. This is not only a problem for water in the basement, but can also cause issues with prematurely destroying the roof of the house.

5. Inspect the basement floor and walls. Fill any cracks with sealant in low traffic areas. In higher traffic areas use a high strength non-shrink mortar mix to fill small cracks. If water is present around the basement perimeter, it will be more difficult to enter the living space if the basement walls and floor are sealed tight.

6. Place low permeability clay near the top 6 inches of the ground around the perimeter of the house. Low permeability clay is also known as fat clay and is similar to modeling clay. The clay should be placed at a ½ inches per foot grade to allow water to run off away from the building instead of being able to seep into the ground and into the basement. If desired, the clay can be placed under plantings or landscaping, just make sure that the top of the clay layer is set properly to force the water that seeps into the landscaping to run away from the building.

7. If all these methods fail to find a problem and improve the water that is reaching the perimeter drain system, consider improving the system around the basement. The basement walls should have perforated drain lines around the perimeter that are surrounded by "clean" (without fine material) stone backfill. The drains should collect and feed into a sump. The water that is collected in the sump should automatically be pumped out with a small submersible pump. It is wise to have a backup pump and generator system should the first pump fail and the electricity goes out. A water alarm is also recommended, so a notification is sent out if the basement sump water elevation exceeds a set level.