Retaining walls are used to create a transition from one level of ground to another. By cutting into a slope and allowing for level ground both above and below the wall, retaining walls increase the amount of flat, usable ground in a yard. Building a retaining wall is suitable for DIYers as long as the wall is a maximum of 3 feet tall (in most areas). Anything taller should be handled by professionals.
The easiest way to build a stone retaining wall is to use the dry-stack method that requires no mortar between stones and does not need a concrete footing, like mortared walls do. Dry-stack walls also drain well, allowing water to pass through the wall itself. This helps reduce hydrostatic pressure imposed by wet soil behind the wall, which is the most common cause of retaining wall failure. Backfilling the wall with rock promotes drainage through the wall and prevents soil from pushing through the cracks in the wall’s stones.
Codes and Regulations
Check with your city’s building authority for applicable building code rules and zoning laws governing retaining walls. Most areas require an engineer’s stamp for walls over 3 feet, but some draw the line at 30 inches. Also, your city may require a permit and inspections for retaining walls of any height, even if you do the work yourself. Be sure to check before you build.
Call before you dig. Before breaking ground on your project, call 8-1-1, the national “Call Before You Dig” hotline, to have all underground utility lines marked on your property. This is a free service that can take a few days, so call well in advance of starting your project.
Source: The Spruce