Grading & Drainage
Defects in soil grade and water drainage around homes is a common problem that should be corrected to improve the longevity of your home's foundation performance. Things like high soils, low soils, erosion and improper drainage are normally easy to repair. These are sometimes a problem from the time a home is built and sometimes they happen over time.
High soil levels can contribute to water intrusion and wood destroying insects. High soil levels allow moisture to enter through weep holes, conceal observable defects in the foundation perimeter beam and hide the entry points of wood destroying insects. Proper soil level (including mulch) at the foundation should allow 4-6 inches of the foundation to be visible in all areas.
Improper grade slope may also allow unwanted water to damage a home's foundation over time or even enter the walls. Proper grade slope is when the soil is graded downward and away from the foundation at a slope of about 6 inches per 10 feet. Water should never flow towards the foundation.
Negative grade slope is when the slope is downward towards the house. Negative grade is a problem that should be corrected to prevent possible flooding, water intrusion into the home, water ponding, soil erosion and other problems.
Today's Texas building standards and Home Inspection standards also recommend that homes be constructed 12 inches or more above the street level.
Water should not pond or stand within 10 feet of the foundation for more than 24 hours. If it does, there is a grading and or drainage defect that should be corrected. Proper grade slope and soil levels at the foundation ensure that water drains away properly.
Soil erosion at the foundation weakens the foundation's ability to properly support the house. Soil erosion is most often caused by improper soil levels such as low soil at the foundation, improper drainage and defect in rain gutters. Soil erosion is also common when grass or other ground covering plants are missing. Grass and ground covering plants help retain soil at the proper height at the foundation.
Properly installed rain gutters are an important factor in maintaining proper grading and drainage. Ideally, rain gutters should have gutter extensions that extend about 5 feet from the house to move water away from the foundation. More commonly, splash blocks are placed at the gutter downspouts to dissipate water at the soil line. If rain gutters don't have 5 foot extensions, then splash blocks should be in place. The lack of gutter extensions or splash blocks contribute to soil erosion.
Maintaining the proper moisture content in the soils around the foundation is important for long term foundation performance. Correct grading and drainage are important parts of keeping the proper moisture levels in the soil that supports the foundation. Keeping the soil moisture level consistent is key to foundation maintenance. Proper grading and drainage help to control the moisture level in the soil that supports the foundation.
Homeowners can often achieve proper soil, mulch levels and drainage on their own. However, sometimes the services of a professional are needed for larger corrections. Landscaping companies are normally equipped to make grading and drainage corrections that are beyond the abilities of the homeowner.
David Selman, Certified Master Inspector #10299
www.selmanhomeinspections.com
469-371-3228
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