Hardscape
Retaining wall cost
A retaining wall 40 ft long and 3 ft tall is about $6,453 in segmental block — $54 a square foot of face, 462 blocks with the buried course — and every figure here includes what stands behind it: clean stone, a pipe at the base and filter fabric, because water is what pushes walls over. Poured concrete is about the same at $53 a square foot; timber is cheapest at $36 and shortest-lived; stone is $77. Past 4 ft, or with a driveway or slope above, the wall is an engineer's: 6 ft of block is $15,643.
Written and edited by Pablo Ruiz Quintero
Last reviewed 2026-09-25 · Nothing you type leaves your browser
Retaining wall cost calculator
The wall, and the water behind it
Length along the wall and exposed height above the ground in front. The buried course, the footing and the drainage are added for you.
Dry-stacked concrete wall block with a lip that sets the lean back into the hill. The standard garden wall.
Along the face.
Exposed, above grade.
Cuts, corners, breakage.
Level ground behind.
New wall.
A contractor.
Used only to pick a regional labour rate. It stays in your browser.
40 × 3 ft segmental block wall
$6,453
$54 a sq ft of face · $161 a linear ft · 462 blocks
Under the 4 ft line
A 3 ft wall with level ground behind it is built to the manufacturer's details without an engineer in most places. The drainage behind it — $468 — is what decides how long it stands.
Why walls fall over
Water, not soil.
Saturated soil pushes on a wall with close to twice the force of dry soil. Clean stone behind the wall and a pipe at its foot let that water out; without them, a wall built perfectly still bulges, leans and goes over after a wet season.
Six ways to build it
40 × 3 ft, drainage included, by a contractor.
What the contractor charges for
- 462 blocks
12 × 4 in wall blocks, 5% for cuts and breakage. Courses: 11 courses. Cap blocks: 40 caps.$2,385 - 7 tons #57 stone, 42 ft pipe
Clean #57 stone 12 in thick behind the wall, a perforated pipe at the base carried out to daylight, and filter fabric between the stone and the soil. Plus 1.8 tons of crusher run for the leveling pad. 220 sq ft of fabric.$468 - Excavation and building
120 sq ft of wall face.$3,600
What it costs
National average. A 40 ft segmental block, 12 × 4 in wall, 3 ft exposed, with the buried course or footing, drainage stone, pipe and fabric. Not included: moving large amounts of soil off site, stairs or curves, or veneer on a CMU wall.
The drainage on its own, on the French drain page; the stone by the ton, on the gravel calculator; a patio in front of it, on the paver page.
Worth knowing
- 40 ft long and 3 ft tall is 120 sq ft of wall face. Segmental block, 12 × 4 in: 462 blocks, with 5% for cuts and breakage. Expect 50+ years from it.
- Behind it, whatever it is made of: 7 tons of clean #57 stone, 42 ft of perforated pipe at the base carried out to daylight, and 220 sq ft of filter fabric. Water pressure is what pushes walls over — $468 of drainage is the cheapest part of the job to get right and the most expensive to add later.
- The first course goes below grade — about 6 in, one inch for every foot of exposed height — on a 6 in compacted gravel pad (1.8 tons). It is what stops the wall sliding forward.
On this page — 5 sections
What a retaining wall costs
The short version
- 40 × 3 ft of block: $6,453. $54 a square foot of face, drainage included.
- Timber $36/sq ft, stone $77. Concrete and CMU in between.
- Over 4 ft, an engineer. 6 ft of block is $15,643.
- The drainage is not optional. $468 of stone, pipe and fabric.
A retaining wall is priced by the square foot of its face — length times exposed height — because that is what sets the blocks, the concrete, the excavation and the labour. Every kind of wall also has the same things behind and below it: a buried course or a footing, a foot of clean stone behind the full height, a perforated pipe at the base carried out to daylight, and filter fabric. Those are in every figure here, because a wall without them is a wall that will be rebuilt.
$6,453
Block wall
40 × 3 ft
$54
Per sq ft of face
Installed
$161
Per linear ft
3 ft tall
$2,288
Small wall
20 × 2 ft block
MaterialsEstimator, Retaining wall price survey · checked 2026-09-25
Block, concrete, timber or stone
Segmental block is the default: dry-stacked, self-aligning, buildable by a homeowner, and about the same price as poured concrete at garden heights. Poured concrete is the strongest and the one for tall walls, driveways and tight spaces, because it is thin for its strength. Reinforced concrete block is a mason’s wall that is usually faced with stucco or stone. Timber is the cheapest and lasts a fraction as long. Dry-stacked stone is the dearest because it is fitted by hand, and lasts longest.
| 40 × 3 ft wall | Buy | Per sq ft | Installed | Lasts |
|---|---|---|---|---|
| Segmental block, 12 × 4 in | 462 blocks | $54 | $6,453 | 50+ years |
| Large segmental block, 18 × 6 in | 199 blocks | $50 | $6,041 | 50+ years |
| Poured concrete | 7.3 cu yd | $53 | $6,403 | 50–100 years |
| Concrete block (CMU), reinforced | 189 blocks | $44 | $5,339 | 50+ years |
| Treated timber, 6 × 6 | 58 timbers | $36 | $4,294 | 15–25 years |
| Natural stone, dry-stacked | 12.1 tons | $77 | $9,295 | 100+ years |
Drainage, buried course or footing and 5% waste included. By a contractor, national average.
MaterialsEstimator, Paver and hardscape price survey · checked 2026-09-16
MaterialsEstimator, Delivered ready-mix price survey · checked 2026-09-15
American Wood Protection Association, AWPA U1 — Use Category System for treated wood · checked 2026-09-25
The water behind the wall
Retaining walls do not usually fail because the soil is too heavy. They fail because the soil gets wet: saturated ground pushes on a wall with close to twice the force of dry ground, and it builds up over a wet fortnight, not a single storm. The answer is the same for every wall — clean #57 stone, never crusher run with its fines, about 12 in thick behind the full height; a perforated pipe at the base carried out to daylight; filter fabric between the stone and the soil so it does not silt up; and the downspouts that now empty behind the wall sent somewhere else.
National Concrete Masonry Association, NCMA Design Manual for Segmental Retaining Walls · checked 2026-09-16
MaterialsEstimator, Delivered aggregate price survey · checked 2026-09-16
Over four feet, an engineer
The building code draws the line at walls holding back more than 4 ft of soil, measured from the bottom of the footing, or holding back any surcharge — a slope rising behind the wall, a driveway, a parking area, a building. Those need a design that checks the wall against overturning and sliding: in block, that means layers of geogrid run back into the compacted hill; in concrete, a thicker wall and a wider footing with more steel. With the design, the permit and the geogrid, a 6 ft block wall is $15,643 against $6,453 for 3 ft — more than double for twice the height.
| Under 4 ft, level ground behind | Over 4 ft, or a load above | |
|---|---|---|
| 40 ft of block | $6,453 (3 ft) | $15,643 (6 ft) |
| 40 ft of poured concrete | $6,403 | $15,826 |
| 3 ft of block with a driveway above | — | $8,637 |
| Design | Manufacturer's standard detail | Engineer's stamped design |
| Permit | Often not needed | Usually needed |
International Code Council, IRC R404.4 — Retaining walls (2021) · checked 2026-09-25
What goes wrong
Before anyone digs
- The line staked and the exposed height measured along it.
- What is above the wall: slope, driveway, building — or level ground.
- Where the pipe at the base can run out to daylight.
- The downspouts that drain behind the wall rerouted.
- 811 called and the utilities marked.
- Over 4 ft, or with a load above: an engineer and the permit.
01No drainage stone or pipe
Water pressure pushes the wall over after a wet season.
Instead — 12 in of clean #57 stone and a pipe to daylight.
02Crusher run behind the wall
Its fines hold water instead of draining it.
Instead — Washed, clean stone.
03First course on the surface
Nothing stops the wall sliding forward.
Instead — Buried an inch per foot of height, at least 6 in.
04Base not compacted or not level
Every course above repeats the error.
Instead — 6 in of compacted gravel, the first course perfectly level.
05A tall wall built as a short one
It rotates and goes over, often without warning.
Instead — Engineered, or terraced into two.
06Above-ground lumber for a timber wall
It rots against the soil in a few years.
Instead — Ground-contact timbers, UC4A or UC4B.
- 01Stake the lineMark the face of the wall and measure its length, including any returns into the slope at the ends.
- 02Measure the heightFrom the finished ground in front to the finished ground behind. Where it varies, average it or price it in sections.
- 03Look above the wallA slope, a driveway, a parking area or a building behind the wall is a surcharge, and brings in an engineer.
- 04Choose the wallBlock for most garden walls; poured concrete or CMU for tall walls and driveways; timber for short and cheap; stone for looks.
- 05Plan the water outWhere the pipe at the base will run to daylight, and where the downspouts that now dump behind the wall will go.
- 06Call 811Before any digging, have the buried utilities marked; the excavation behind a wall is wider than it looks.
The pipe at the foot of the wall is a French drain: priced by the foot with the stone by the ton, and an outlet that works.
Where the water goes- Segmental retaining wall (SRW)
- Dry-stacked concrete wall blocks with a lip or pins that set each course slightly back. The common garden wall.
- Exposed height
- The height of the wall above the ground in front of it. The buried course or footing is below it.
- Buried course
- The first course of block set below grade — about an inch per foot of exposed height, at least 6 in. It stops the wall sliding forward.
- Leveling pad
- The compacted gravel base, about 6 in thick, the first course sits on.
- Drainage aggregate
- Clean crushed stone, usually #57, about 12 in thick behind the wall, so water drains down to the pipe instead of pushing on the wall.
- Surcharge
- Any load above and behind the wall — a slope, a driveway, a building. It adds pressure and brings in the engineer at lower heights.
- Geogrid
- A plastic mesh laid between courses and run back into the compacted soil, tying a tall block wall and the hill together.
- Deadman
- A timber laid perpendicular into the hill and fixed to a timber wall, anchoring it.
- Batter
- The backward lean of a wall's face into the slope it holds.
- Weep hole
- An opening near the base of a solid wall that lets trapped water out.
Common questions
- How much does a retaining wall cost?
- A 40 ft long, 3 ft tall segmental block wall is about $6,453 installed, with the drainage stone, pipe and fabric behind it — $54 a square foot of face or $161 a linear foot. The same wall in poured concrete is $6,403, reinforced concrete block $5,339, treated timber $4,294 and natural stone $9,295.
- How much does a retaining wall cost per square foot?
- Per square foot of wall face, installed with drainage: about $36 for timber, $44 for CMU, $54 for segmental block, $53 for poured concrete and $77 for dry-stacked stone, at 3 ft tall. Taller walls cost more per foot: 6 ft of block is $65 with the engineering and geogrid.
- How many retaining wall blocks do I need?
- Blocks per course is the wall length divided by the block width; courses is the exposed height plus the buried course, divided by the block height. A 40 × 3 ft wall in 12 × 4 in blocks is 11 courses of 40 — 462 blocks with 5% for cuts, plus 40 caps.
- How much does a concrete retaining wall cost?
- About $6,403 for 40 ft × 3 ft poured in place — 7.3 cubic yards of ready-mix on a footing, forms and rebar, drainage — or $53 a square foot. At 6 ft tall, with a thicker wall, a wider footing and an engineer, $15,826. A reinforced concrete block (CMU) wall is about $5,339 for the 3 ft wall, before any stucco or veneer.
- How tall can a retaining wall be without an engineer?
- About 4 ft in most places, measured from the bottom of the footing — and less, or any height, when there is a slope, a driveway or a building above it. Past that, the design, the permit and, for block, geogrid add about $2,405 to a 40 ft wall. Terracing into two walls under 4 ft, set back at least twice the lower wall's height, usually avoids it.
- Is a retaining wall a DIY project?
- A block or timber wall under 3 or 4 ft is a reasonable first wall: the 40 × 3 ft block wall is about $3,033 in materials and tool rental, and a 20 × 2 ft wall about $1,268. The whole job is the base course — dug deep enough, on compacted gravel, perfectly level. Poured concrete, stone and tall walls are for a contractor.
- How much does it cost to fix or replace a retaining wall?
- A wall that is leaning or bulging is rebuilt rather than pushed back: the old one broken out and hauled away (about $14 a square foot of face) and a new one built with the drainage the old one probably lacked. For 40 × 3 ft of block, that is about $8,133. A short section that has shifted can be taken down and relaid for much less.
- Why do retaining walls fail?
- Water. Saturated soil pushes on a wall with close to twice the force of dry soil, and a wall with no clean stone behind it and no pipe at its foot gets that full push after every wet spell. The other causes are a first course that was not buried, a base that was not compacted, and a wall taller than its design.
- What is the cheapest retaining wall?
- Treated timber: about $4,294 for 40 × 3 ft, against $6,453 in block. It also lasts 15–25 years rather than 50 years or more, so over the life of the wall block is usually the cheaper one.
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About the author
Pablo Ruiz Quintero — Editor
Editor of MaterialsEstimator. Decides which documents count as a source, what every default value is, and where the line sits between what the reader parses and what the engines compute.
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