Drainage behind every wall
Red clay holds water, and saturated clay pushes hard against anything in its way. Every wall we build gets:
- A compacted gravel footing, set below grade so the first course is buried
- Clean crushed stone backfill behind the wall, so water can drain down to the pipe
- A perforated drain pipe at the base, run to daylight or a drain so the water has somewhere to go
- Geogrid reinforcement on taller walls, layers of grid that tie the wall into the soil behind it
Permits and engineering
Georgia’s residential building code exempts retaining walls 4 feet tall or less, measured from the bottom of the footing to the top of the wall, unless the wall supports extra load such as a driveway or a slope above. Above that, cities require a permit, and many require a design sealed by an engineer. Sandy Springs, for example, requires an engineer’s seal at 6 feet, and Roswell asks for engineered design on any wall over 4 feet.
Walls near streams and the Chattahoochee face extra limits no matter their height. Your town’s page lists the local rules.
Terracing a steep yard
One tall wall is rarely the best answer. Two or three shorter walls with planting between them often cost less, may not need engineering, and look better. They also turn a slope into level spaces you can use: a patio on one terrace, a lawn or garden on the next.
What affects the price
- Wall height and length. Height adds cost faster than length.
- Material: segmental block, natural stone or boulders
- Whether the wall needs engineering, geogrid and a permit
- Access: walls in back yards with no equipment access take more hand work
- Removing an old failing wall first