A professionally built retaining wall usually costs $20 to $50 per sq ft of wall face, with a national average around $6,300. Wall face is the length times the height, so a 30 ft long, 3 ft tall wall is 90 sq ft. Building a block wall yourself, the materials for that same wall come to about $1,650, including drainage stone and pipe.
Count your blocks first. The free retaining wall calculator figures blocks per course, caps, base gravel, drainage stone, pipe, and fabric for your wall, with prices you can edit.
Retaining wall cost by size
| Wall (length x height) | Wall face | Installed ($20 to $50/sq ft) |
|---|---|---|
| 30 x 2 ft | 60 sq ft | $1,200 to $3,000 |
| 30 x 3 ft | 90 sq ft | $1,800 to $4,500 |
| 50 x 3 ft | 150 sq ft | $3,000 to $7,500 |
| 50 x 4 ft | 200 sq ft | $4,000 to $10,000 |
| 100 x 3 ft | 300 sq ft | $6,000 to $15,000 |
Walls over about 4 ft usually need an engineered design and more reinforcement, so expect the cost per sq ft to climb with height.
Cost by material
| Material | Installed cost per sq ft of face | Notes |
|---|---|---|
| Wood timbers | $10 to $35 | Cheapest, but lasts the shortest |
| Cinder block | $10 to $40 | Usually faced with stucco or veneer |
| Interlocking concrete block | $12 to $35 | The usual DIY choice, no mortar |
| Poured concrete | $16 to $40 | Strong, good for taller walls |
| Natural stone | $20 to $90 | Highest cost, most labor |
Ranges combine figures from the sources below, which vary a lot by region.
What adds to the cost
- Height: taller walls need a deeper buried course, geogrid reinforcement, and often an engineer. Rebar for concrete walls adds about $1.50 to $2.50 per sq ft.
- Drainage: gravel backfill, a perforated drain pipe, and filter fabric behind the wall. Skipping drainage is the most common reason walls fail.
- Excavation: about $50 to $200 per cubic yard, plus hauling away the soil.
- Grading: at least $500 for most yards.
- Access: block, gravel, and soil all move by hand if equipment cannot reach.
- Permits: often $40 to $450, and commonly required for walls over 4 ft.
- Caps, steps, and curves: each adds cutting and labor.
DIY retaining wall: materials only
Here is what the retaining wall calculator lists for a 30 ft long, 3 ft tall wall in medium block (16 x 6 in face):
- 170 blocks (6 courses above grade, plus 1 buried)
- 24 wall caps and 3 tubes of masonry adhesive
- 2 tons of crusher run for the leveling base
- 5.5 tons of #57 drainage stone behind the wall
- 3 pieces of 4 in perforated drain pipe
- 1 roll of filter fabric, plus bulk delivery
- About $1,650 in materials, or about $18 per sq ft of face
A 50 ft long, 2 ft tall wall comes to about $2,025. Add a plate compactor rental, a level, and a saw with a masonry blade for cuts.
When to hire a pro
- Walls over about 3 to 4 ft tall, or any height your town says needs a permit or engineer
- Walls holding up a driveway, a building, or a steep slope
- Wet sites or anywhere water already collects
- Tiered walls, where the upper wall loads the lower one
FAQ
How much does a 30 ft retaining wall cost?
At 3 ft tall, about $1,800 to $4,500 installed, or about $1,650 in block and drainage materials to build it yourself.
What is the cheapest retaining wall?
Wood timbers or plain concrete block are usually cheapest. For DIY, interlocking block is the best value, since it needs no mortar or footing beyond a compacted gravel base.
Do I need a permit for a retaining wall?
Many towns require one for walls over 4 ft, and some for shorter walls or any wall near a property line. Check with your building department.
How deep should the first course be buried?
A common rule is 1 in of buried block for every 8 in of wall height, with a minimum of about 6 in. Follow the block maker’s instructions.