Grading and Landscaping
By Kenton Shepard
Protecting the Home Foundation
Moisture allowed to penetrate next to the foundation can cause several problems...
- Softening the soil- moist soil may be less able to support the weight of the structure above.
- Expansive soil- Certain types of soil, especially certain types of clay, expand to many times their original size as they absorb moisture. Expansive soil can easily damage foundations.
- Foundation undermining- enough moisture flowing under a foundation can carry away soil and leave the foundation unsupported in areas.
- Microbial growth- moisture allowed to collect in crawlspaces and basements may create conditions which encourage the growth of microbes such as mold fungus and soil-borne bactieria which may represent potential health hazards.
Slope Grade Away from Foundation
Grade around the home perimeter should slope away from the foundation for at least six feet. The slope should effectively route surface runoff away from the foundation.
Hillside Run-off
Homes built on hillsides should have a feature installed which will route surface runoff away from the foundation. Swales and drainage ditches are two commonly-used methods.
Planting Beds
Planting beds located next to the home may create problems by holding moisture next to the foundation.
Downspouts
To minimize erosion and route runoff away from the foundation, downspouts should have extensions or should terminate at a perimeter drain or splashblock. Some method sould be used to prevent erosion.
In a new home- the beginning of a gully
Strategic Landscaping
Sun Control
Deciduous trees planted to shade walls and windows help keep a home cool during the summer will allow the winter sun to shine through during the winter, helping to warm the home and lowering heating costs.
Wind control
A home can be protected from wind by planting evergreen bushes, hedges or trees, upwind of the area to be protected.
Snow Drift Control
Wind of 20 MPH or more will pick up fallen snow. Landscaping can be used as natural snow fencing. Bushes and hedges will slow the wind, causing it to drop the snow it carries and controlling drifting. Landscaping planted for this purpose must be planted well back forom the area it's intended to protect, just like a conventional snow fence.
Driveways and Walkways
Permeable Materials for Walks and Drives
Instead of paving driveways and walkways, surfacing them in a manner which allows surface runoff to be absorbed helps prevent soil erosion, limit pollutants being washed into local water supplies, reduce irrigation requirements and help replenish soil moisture and local aquifers. Limiting paved surfaces to 1/3 of walks and drives and less concrete being placed will also lower the total embodied energy of the home site.
Limiting the Graded Area
Areas which are graded are more likely to suffer from erosion problems than areas which are left with natural vegetation. Limiting site grading to an area within 20 feet of the building footprint will minimize the impact on the lot and help control erosion.
Sharing Driveways
Sharing a driveway can reduce the impact on neighboring lots, especially if homes are set back a considerable distance from the road.
Road/drive follows Natural Topography
To minimize impact on the site and avoid creating erosion problems, roads and driveways should follow as closely as possible the natural topography of the lot. This means avoiding deep cuts where they could have been avoided with little additional impact.
Fire Mitigation
Home in areas in which wildfires are a concern should put into effect a wildfire safety program.
Sources for More Information
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