Retaining Wall Installation in Charlotte, NC

A footing set below frost depth, gravel backfill and a drain line behind the wall to relieve water pressure before it builds up, and coursing in block or natural stone matched to the style of the property. Getting the drainage right behind the wall is what keeps a new wall from becoming a leaning one in a few years.

North Carolina sets a height at which a retaining wall has to be designed by a registered engineer rather than built to standard detail. Under the current residential code the threshold is five feet, measured as the cumulative height of the wall, and a tiered system is treated as one wall where the tiers sit within fifteen feet of each other horizontally.
The four-foot figure still quoted on a lot of contractor sites comes from the previous code cycle and no longer matches what the code says. Which side of the line a wall falls on is established during the site visit, from the actual grade change, not estimated after the fact — it changes both the scope and the cost, and it is the kind of thing that is expensive to discover once a wall is already going up.