Retaining Walls and Grading in Sandy Springs

What the scope covers

• Wall type chosen for the job: segmental block for straight structural runs, stacked boulder for a natural creek-side look, mortared stone where the wall is architectural
• A compacted crushed-stone base set below finished grade, so the bottom course is buried and cannot kick out
• Free-draining stone backfill and a perforated drain line behind every wall, daylighted to a point that runs under load
• Geogrid reinforcement layered into the retained soil on taller walls, tied to the manufacturer specification rather than to a rule of thumb
• Backfill compacted in lifts, with the clay kept out of the drainage zone where it would clog the aggregate
• Terracing where one tall wall would be worse than two short ones, which is often the honest answer on a steep Sandy Springs lot
• A wall section drawn before the first course goes down, showing base depth, backfill, drain line and any geogrid, so the buried work is agreed rather than improvised

To have this priced on your own property, call (404) 737-3568 or use the quote form. Someone walks the yard, takes measurements, and leaves a written scope with a price on it. No charge for any of that.

Read next

• The Sandy Springs landscaping guide
• What landscaping costs here
• Working with Georgia red clay
• The glossary, for the words that turn up on a quote

On walls and grading, specifically

When does a wall need an engineer?

Earlier than most homeowners expect, and height on its own is not the test. What decides it is the load: a driveway, a pool or a slope sitting above the wall all add surcharge, and a tall wall retaining a steep bank of wet clay is a structure rather than a garden feature. The honest rule of thumb is that any wall tall enough to make you ask the question is a wall that should be designed by someone willing to sign the drawing, and the manufacturer of a segmental block system will set out where its own reinforcement tables stop.

Why do so many walls around here lean out after a few years?

Almost always drainage. A wall with clay packed directly behind it is a dam, and every storm loads it. Add the freeze-thaw cycles this climate does deliver at the margins of winter and the wall walks. The remedy is unglamorous and mostly invisible: washed stone behind the block, a pipe at the base that daylights somewhere real, and a base course buried below finished grade. A wall that had none of those cannot be fixed by re-laying the top courses.

Can grading change where water goes onto my neighbor?

It can, and that is the risk worth taking seriously on a sloping lot. Every cut and fill changes where storm flow collects and where it leaves, so a regrade that cures your low corner by tipping the water over the boundary has not solved anything, it has moved the problem next door and made it someone else's. The way to avoid it is to work out where the water goes across the whole property before the machine arrives, and to give the regrade a destination of its own rather than letting it find one.

What does a wall do to the trees above it?

Cutting into a slope cuts roots, and on a Sandy Springs lot the roots above a wall usually belong to a mature hardwood. A tree can lose a surprising amount of its root plate and look fine for three or four years before it declines, which is long enough that nobody connects the wall to the dead oak. A wall alignment that stays outside the critical root zones of the trees you want to keep is worth redrawing for, because a redraw costs an afternoon and a forty-year oak cannot be bought back at any price.

Block, boulder or mortared stone?

Segmental block is the most predictable structurally and the easiest to reinforce with geogrid, which is why it dominates on tall walls. Boulder walls suit creek-side and woodland settings and are forgiving of irregular alignments, but they eat space, because a boulder wall leans back into the hill. Mortared stone is the most expensive and the least tolerant of movement, which makes it a facing choice for shorter architectural walls near the house rather than a way of holding back a hillside.