Cost · permit · scope
Retaining Wall planning guide
Plan a retaining wall: height counted from the footing, the 4 ft permit line, when it needs an engineer, and the drainage stone that goes behind it.
Permit complexity
High
Compare quotes per
square foot of wall face
| Percentile | U.S. | California | Texas |
|---|---|---|---|
| 25th percentile | $18.57 | $23.15 | $17.66 |
| Median | $22.66 | $28.98 | $19.53 |
| 75th percentile | $28.72 | $37.75 | $22.57 |
Retaining wall buying path
Measure from the footing, then follow the water.
Two walls with the same face can differ by a permit and an engineer: what counts is the height from the bottom of the footing, the load above, and where the water behind it goes.
01 · Measure
Count what is buried
Take the height from the bottom of the footing to the top of the wall at its tallest point. That is the number the permit line reads, not the face you see.
02 · Load
List what sits above
A driveway, parking or a building on the soil above is a surcharge, which ends the exemption and, past 24 inches, calls for an engineered design. Settle what the wall carries before choosing the block.
03 · Drain
Plan where the water goes
Send surface water away from the wall first. Behind a block wall the concrete-masonry guide calls for at least 12 inches of free-draining stone and a drain pipe of 3 inches or more, with outlets no more than 50 feet apart.
Decision matrix
Compare one specification at a time
Segmental block
A wall built without mortar or forms
Specify the block system, leveling pad, drainage stone depth, drain pipe and any geogrid layers.
Poured concrete
A thin wall where space is tight
Specify footing size, reinforcement, wall thickness, weep holes and the waterproofing on the back.
Timber
A short wall around a garden bed
Specify ground-contact treatment, anchors or deadmen, post spacing and how water gets through.
Quote controls
Keep every bid comparable
- Same length, height from the footing and top detail
- Excavation, base and footing depth itemized
- Drainage stone depth, drain pipe size and outlet locations shown
- Engineering, permit and grading responsibility assigned
- Soil hauled off or brought in, in cubic yards
Next best action
Calculate, then lock the scope.
Size the drainage stone along the wall's length in the gravel calculator, then have every bidder price the same footing depth, wall height and drain line.
Start with two separate questions
No permit under the model code up to 4 ft from the bottom of the footing, unless the wall supports a surcharge.
Where it stands and what it does to the neighbor's grade are zoning and grading questions; settle both before digging.
What usually decides the scope
- Height from the bottom of the footing
- Load on the soil above it
- Soil type and drainage
- Depth of cut or fill
- Property-line location
Height
The model code, Austin and Los Angeles read the 4-foot line from the bottom of the footing to the top of the wall, so the buried courses count as much as the face you see.
Drainage
The concrete-masonry guide treats the stone and pipe behind a block wall as relief for incidental water, not its main drain: water should be sent away from the wall before it gets there.