Whether your home has a slab foundation, crawl space or basement, you want to create an exterior slope that prevents water from collecting around the house. To keep water from damaging your foundation, the ground must slope down and away from your house. If the ground or landscaping slopes toward your foundation, water will collect and eventually work its way into the concrete. Because concrete is porous, water easily seeps into the foundation walls and therefore into your basement or crawl space.
Measure 10 feet out from the foundation wall. Push a wooden stake in the ground close to the foundation and another one at the 10-foot mark.
Tie one end of a piece of string at least 12 feet long to the stake near the foundation. Pulling the string taut as you go, bring the other end of the string to the stake located at the 10-foot mark. Use a level to be sure the string is straight and level before securing it to the stake.
Measure the distance from the string to the ground at both stakes. The distance from the string to the ground at the 10-foot stake should be at least 6 inches more than the stake near the foundation. This is the minimum requirement for residential settings. If the distance is 6 inches or more, the grade of the ground near your foundation is just fine.
Repeat at various points around your foundation. Check all questionable areas around your foundation to be sure the grading is sufficient. If the grading around your house meets or exceeds minimum requirements, your job is done. If your grading falls short, you need to fix it.
Record your measurements, making note of where each was taken, if you have to change the slope.
Deposit dirt near the foundation and outward toward the 10-foot mark. Your goal is to attain a slope in which the ground at the 10-foot mark is at least 6 inches below the ground at the foundation. Use your measurements to determine where to put the dirt and how much to put down.
Pack the dirt. Tamp down the dirt with shovels to compact it a bit and keep it from shifting. Remove the stakes and string.
Finish the soil as you wish. This may mean adding sod or grass seed, flowers or lawn ornamentation.
When calculating the slope around your foundation, it is helpful to have an assistant. It will save you time and effort, especially while tying the string and making sure it is level. If the slope of the ground around your home is within minimum requirements and you still have water problems with your foundation, contact a foundation inspector. Soil type as well as drainage issues not related to the slope can contribute to water problems. An inspector can tell you exactly what the problem is and how to fix it. Building code requires the top of foundations be at least 6 inches above the highest point of the ground. If a foundation is lower than that, it increases the chance of water damage, regardless of the slope of the ground. If this is your situation, do not add soil to change the grade of the ground near your foundation. Instead, you will need to remove ground from around the foundation until you meet the code requirement. From there, you may have to remove soil going out from the house in order to establish proper grading. Any time the ground around the foundation is changed, whether through landscaping or building additions, be sure the slope is considered before, during and after the project.