Virginia Engineering and Permit Requirements
The Virginia Residential Code, section R404.4 states:
Retaining walls that are not laterally supported at the top and that retain in excess of 48 inches of unbalanced fill, or retaining walls exceeding 24 inches in height that resist lateral loads in addition to soil, shall be designed in accordance with accepted engineering practice to ensure stability against overturning, sliding, excessive foundation pressure and water uplift.
In addition, the Virginia Construction Code requires a permit for any retaining wall supporting 36 inches of unbalanced fill.
Unbalanced fill refers to the soil being retained on the back side of the wall. Lateral loads are caused by a surcharge (like a car or slope), fence, or water pressure. Water pressure is the result of groundwater, surface water, or nearby water bodies.
So if you have one or multiple walls with a total height greater than 3 feet (including the buried portion) or a wall greater than 2 feet that supports a surcharge, you need the services of a professional engineer. Also, check with your local county/city to determine if they have more stringent requirements.
In addition, retaining wall design will need to consider frost depth. This will increase as you head west. The frost depth is 12 inch in the eastern cities of Virginia Beach, Norfolk, Chesapeake, Hampton, and Newport News. The frost depth is 18 inches in Richmond and 24 inches in Roanoke.
Virginia Contractors
If you are looking for a contractor in southern Virginia, we recommend Top Gun Enterprise, LLC.