Type of Work
Retaining Walls and Grading in Sandy Springs
Slope turned into usable ground, with drainage behind the wall rather than pressure.
A great many Sandy Springs lots fall steeply from the street toward a creek, which is why so much of the useful outdoor space here has to be made rather than found. A retaining wall is the tool for that, and it is also the single element of a residential landscape most likely to fail, because the thing a wall resists is not soil weight but water. Clay behind a wall holds water, water adds hydrostatic pressure, and a wall built without drainage behind it leans out and then bulges within a few winters. Everything that matters is buried: a compacted base below grade, free-draining stone backfill, a drain pipe daylighted somewhere it will run under load, geogrid layers tied back into the retained mass on anything tall, and compaction done in thin lifts rather than in one push. The visible course of block or stone is the last five percent. Grading works the same way. Moving earth around on this ground changes where water goes, and that is why the city treats it as a permitted activity rather than yard work.
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
- Land disturbance permitting, erosion control measures and the retaining wall detail sheet the city asks for on the construction drawings
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
On walls and grading, specifically
- How tall can a wall be before it needs an engineer?
- Height thresholds for engineered design come from the building code and from the wall manufacturer, and they vary with the surcharge above the wall, the slope behind it and the soil. What is consistent in Sandy Springs is the paperwork: retaining wall details are listed among the construction drawings required with a land disturbance permit application, so the design gets reviewed by the city rather than left to the crew. Any wall tall enough to raise the question is a wall that should be designed by someone who signs the drawing.
- 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 neighbour?
- It can, which is precisely why the city regulates it. Sandy Springs generally requires a land disturbance permit at 1,000 square feet of disturbance, and says a permit may still be needed below that if the work changes topography or stormwater drainage patterns. Grading plans and drainage plans are both listed among the required submittals. A regrade that solves your low corner by sending the water next door is the kind of thing the review exists to catch.
- 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 protected tree. Removing a hardwood at 18 inches diameter or more needs a permit, and where the wall is part of a construction project the city asks for a Tree Conservation Plan rather than a simple removal permit. A wall alignment that stays outside the critical root zones of the trees you want to keep is worth redrawing for, because it is far cheaper than the alternative.
- 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.
From the Yard Notes
More on this, written for north Fulton
Usually Booked Together
Work that tends to arrive in the same scope
Landscape projects here group themselves around water and grade. A new patio changes where runoff goes, a wall changes the grade above it, and planting into a slope only holds if the water crossing it has somewhere else to be. Pricing the pieces together is usually cheaper than pricing them one at a time.
Landscape Design and Planting
A drawn plan for the whole property, then beds shaped, soil amended and plants set in the right season
Drainage and Erosion Control
Water intercepted, carried and released somewhere legal, so it stops moving soil and standing against the house
Patios, Walkways and Steps
Stone laid on a base that will not move, with the water taken somewhere rather than trapped
Shade Planting Under the Canopy
Beds that work in four hours of filtered light, planted without wrecking the roots holding the trees up
Find out what the yard would cost
Call (404) 737-3568 or use the quote form, and a Sandy Springs landscaping company prices the work at no charge.