How much does a retaining wall cost per linear foot?

Height matters more than length, so per-foot prices for a short garden wall don’t carry over to a tall one. A wall over 4 feet usually needs an engineered design, geogrid and more excavation, and every wall needs drainage stone and pipe behind it. Natural stone also takes longer to lay than block.

What is the best material for a retaining wall?

For most walls that hold real weight, segmental concrete block: it locks together, steps back into the hill and comes with tested design tables. Natural stone and boulders look more natural and suit low walls and garden terraces. Timber is the cheapest up front but rots, so it doesn’t last like block or stone.

Why do retaining walls fail?

Water, most of the time. Wet soil is heavy, and a wall with no gravel behind it and no drain pipe at its base takes the full push of every storm, then bulges and leans. A wall built on loose fill, or with its first course sitting on top of the ground, fails the same way.

Do I need a permit for a retaining wall in Nashville?

Not a grading permit: Metro Water Services lists retaining walls among the work that doesn’t need one. A building permit is a separate question, and Metro doesn’t publish a height threshold for it, so ask Metro Codes about your specific wall before construction, especially if it’s over 4 feet.

When does a retaining wall need an engineer?

Generally when it’s over 4 feet tall. CMHA recommends an engineered design for segmental walls past that height unless local code says otherwise. If a slope, a driveway or a building sits above the wall, it’s worth having an engineer look at it at any height, since that weight adds to the push.

Is one tall wall or two shorter walls better?

Two or three shorter walls stepped up a slope often work better. Each wall carries less load, may stay under the height where an engineer is needed, and the flat terraces between them become planting beds or seating areas. One tall wall takes up less ground and suits a tight lot.

Nashville Retaining Wall Builder | Nashville Outdoor Works

What a retaining wall can do for a yard

A lot of Nashville lots slope, front to back or side to side. A retaining wall cuts that slope into flat ground: a level lawn for the kids, a terrace for a patio, a garden bed at a comfortable height. Two or three shorter walls stepped up a hill often look better than one tall one, and the terraces between them become planting beds.

Block or natural stone?

Segmental block is made for the job. The units lock together, each course steps back slightly into the hill, and they come in colors and faces from smooth to split. Natural stone, dry-stacked limestone or large boulders, looks like it has always been there and suits low walls and garden terraces. Plenty of yards use both, with block where the load is heavy and stone where people look.

What keeps a wall standing

Drainage. Wet soil is heavy, and a wall with nothing behind it to let water out takes the full push of every storm. CMHA’s design guidance calls for a foot of drainage gravel behind the block and a drain pipe at the base, with the first course buried below the ground in front. Skip those and the wall bulges and leans within a few seasons.

Taller walls and permits

CMHA recommends an engineered design for segmental walls taller than 4 feet, and taller walls are usually tied into the hill with layers of geogrid. Metro Water Services lists retaining walls among the work that doesn’t need a grading permit; Metro Codes is the office to ask about a building permit for a specific wall.

Finishing touches

A cap on top makes a low wall into a bench. Steps built into the wall connect one terrace to the next, and lights tucked under the cap make those steps safe after dark.

Sources

CMHA Tech Note SRW-TEC-004 — drainage, buried first course and the 4-ft engineering threshold
Metro Water Services, who needs a grading permit

Retaining walls for sloped Nashville yards