L-06.RW · Retaining Walls & Grading
Segmental block walls, cut-and-fill grading and the drainage behind both. Georgia clay holds water and moves; a wall that was not drained is a wall that leans.
See it built
A retaining wall is holding back soil, and soil that has taken on water is dramatically heavier than soil that has not. Red clay holds water for days after a storm. The pressure that builds up behind an undrained wall is not a slow problem: it is the single most common reason residential walls in this part of Georgia lean, bulge and eventually come apart.
Which is why the drainage behind the wall is not an upgrade or a line item to value-engineer out. It is the wall. The block is the visible part of a system whose actual job is to keep water moving out from behind the structure instead of accumulating against it.
Grading is the same conversation from the other direction. Cut-and-fill work reshapes where water goes across the whole property, and a wall built without thinking about what the regrade sends toward it is a wall that gets asked to do more than it was built for.
The base trench is excavated below finished grade and filled with compacted aggregate, so the first course sits below the surface. A wall that starts at ground level has nothing resisting it at the toe.
The first course is levelled, and levelled properly, because every error in it multiplies the whole way up the wall.
Behind each course goes drainage stone with a perforated pipe at the bottom, and that pipe has to go somewhere. Daylighting it at a low point, or tying it into the property drainage, is what turns it from a detail into a working system. A perforated pipe that terminates in the middle of a backfill is decoration.
Geogrid is laid back into the retained soil at the intervals the wall height requires, which is what lets a segmental wall hold more than its own weight. Height, surcharge and soil all drive that spacing.
The wall is built with the batter the block system specifies, backfilled and compacted in lifts as it rises, and capped.
Quoted by the face square foot, which is the visible height times the length, and that unit exists because it tracks the actual work better than length alone does. A wall twice as tall is far more than twice the job.
Height drives everything: excavation volume, geogrid, the amount of backfill that has to be compacted, and whether the wall needs engineered design at all. Most Georgia jurisdictions set a height at which an engineered drawing and a permit become mandatory, and Floyd County has its own threshold, so that is a question to settle with the county before the design is fixed rather than after.
Then site access for the machine and the block, how much material has to be hauled in or out, whether rock turns up in the excavation, and whether the drainage outfall is a short run to a low point or a long one across the property.
It leans out at the top. This is the classic undrained-wall failure: water pressure behind the structure pushing the upper courses forward, and it gets worse every wet season.
It bulges in the middle, which usually means no geogrid, or geogrid at the wrong spacing for the height.
It steps and separates at a joint, which is a base problem: the first course was not level, or it was not on compacted aggregate, or it was not below grade.
And the one that looks like a landscaping problem: the ground above the wall stays soggy and the plants in it die. That is the drainage system behind the wall not working, showing up at the surface before the wall itself moves.
Where this work leads
Quoted by the face sq ft, line by line, after a site walk. Across 21 counties from the shop in Floyd County.