Tiered stone block retaining wall holding back a sloped yard, with drainage gravel behind the top course

10 · Retaining Walls & Land Stabilization

Retaining walls in Nashville for slopes that grading won’t hold

“We design and build retaining walls” where a slope is too steep to hold itself, or where a flat yard, a driveway or a building pad has to be carved out of a hill.

Call (615) 209-7643 or send the estimate form

Regrade, drain or build a wall

A wall isn’t always the answer. If the slope is gentle enough to mow, grading it smooth and getting grass on it may be all it needs. If the trouble is water running down the bank, a swale or a drain at the top fixes the cause. A wall makes sense when there isn’t room to lay the slope back: the yard would lose too much flat ground, the driveway would get too steep, or the bank is already sliding.

Most of the wall is out of sight

What you see is a face of block or stone. What keeps it standing is underground and behind it. The trench is dug to firm soil and filled with compacted crushed stone for a level base. The first course sits partly below grade, and each course above steps back slightly into the hill.

Behind the wall goes a zone of clean drainage stone, with a perforated pipe at the bottom that carries water out the ends or through the face. Water is what pushes walls over. Clay holding rainwater gets heavy, and a wall with no way to drain it is fighting the full weight. Taller walls also get layers of geogrid, a reinforcing mesh laid back into compacted fill that ties the soil behind the wall to the wall itself.

Excavation to firm subgrade
Compacted stone base
First course buried
Drainage stone and perforated pipe behind
Geogrid in compacted fill on taller walls

Grade changes and Metro’s 18-inch line

Building a wall almost always means cutting into the slope or filling behind it. In Davidson County, Metro Water Services’ grading permit exemption for maintenance and landscaping work holds only when the grade changes 18 inches or less. A wall that terraces a yard by several feet goes past that, so the permit question gets looked at along with the wall’s layout.

What changes the design

Height is the obvious one. Just as important is what sits above the wall. A lawn is one load, a driveway with parked trucks is another, and a house foundation near the top is another again. The soil, the slope above, and the room behind the wall for drainage stone and grid all go into the design before a block is set.

What this covers

Wall design and build
Drainage behind the wall
Slopes held

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Answers

Questions about retaining walls

How much does a retaining wall cost?

Retaining walls are priced by the face area, length times height, and by what it takes to build them right. The material, digging into rock or tight access, how much drainage stone and geogrid the wall needs, and the load above it all change the number. A knee-high garden wall and a tall wall under a driveway are different projects.

Why do retaining walls lean or fall over?

Most fail because of water or the base. Rain soaks the soil behind a wall that has no drainage, the pressure builds, and the wall tips forward. A base that was not dug to firm soil and compacted lets the wall settle unevenly. Tall walls built without geogrid reinforcement can also bulge or slide.

What goes behind a retaining wall?

Clean, angular drainage stone directly behind the blocks, a perforated drain pipe at the bottom that carries water out, and compacted soil beyond that. Filter fabric keeps fine soil from clogging the stone. On taller walls, layers of geogrid extend back into the compacted fill to tie the soil and the wall together.

Is a retaining wall or regrading better for a sloped yard?

Regrading is cheaper when there is room to lay the slope back at an angle grass can hold and a mower can climb. A retaining wall is better when that would eat too much of the flat yard or steepen a driveway, or when the slope is already failing. Many yards end up with a short wall plus some regrading.

What material is best for a retaining wall?

It depends on height, budget and look. Segmental concrete block is common because its courses interlock and it works with geogrid. Natural stone suits lower walls and older properties. Poured concrete handles tall walls and tight spaces but costs more. Treated timber is the cheapest to start and has the shortest life.

Can a retaining wall fix a drainage problem?

Not by itself. A wall holds soil; it does not move water, and a wall built across a wet slope can trap water behind it. The stone and pipe behind a wall protect the wall itself. If the yard has a water problem, a swale, a french drain or regrading belongs in the plan alongside the wall.

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