A professionally installed boulder wall from Wall & Company typically costs $35–$100 per square foot of wall face.
For a 150-square-foot boulder wall, that means a planning budget of approximately $5,250–$15,000.
| Wall Face | Typical Price Range |
|---|---|
| 100 sq. ft. | $3,500–$10,000 |
| 150 sq. ft. | $5,250–$15,000 |
| 200 sq. ft. | $7,000–$20,000 |
| 300 sq. ft. | $10,500–$30,000 |
These are Wall & Company planning ranges for professionally constructed boulder walls in the Spokane area—not national averages.
The biggest variables affecting the final cost are wall height and length, boulder size and type, excavation, equipment access, soil and site conditions, drainage, slope and engineering requirements.
How Is the Size of a Boulder Wall Calculated?
Like other retaining walls, a useful starting point is the square footage of the wall face.
A wall that’s 50 feet long and averages 3 feet high has approximately 150 square feet of wall face:
50 feet × 3 feet = 150 square feet
Using Wall & Company’s $35–$100 per-square-foot planning range, that produces an approximate budget of $5,250–$15,000.
The visible dimensions establish the size of the wall, but much of the work determining its final cost happens behind and underneath the boulders.
How Does Boulder Size Affect the Cost?
Boulder walls rely on the size, weight, shape and placement of individual stones to create a stable structure.
Large boulders require equipment capable of safely lifting, positioning and rotating them. The installer isn’t simply stacking rock. Each boulder needs to be selected and positioned so that it works with the neighboring stones and the overall wall.
A well-built boulder wall should look natural while still functioning as an engineered landscape structure.
That balance requires both appropriate material and experienced equipment operation.
Does the Type of Boulder Matter?
Yes.
Boulders vary in:
- Size
- Shape
- Density
- Color
- Texture
- Source
- Transportation cost
Some stone is relatively uniform and easier to integrate into a wall. Other material has highly irregular shapes requiring more selection and positioning.
The aesthetic choice matters too. Boulder walls are prominent landscape features, and the stone should complement the home’s architecture and surrounding landscape.
The amount of material required and where that material comes from can both affect the project price.
Why Does Equipment Access Matter So Much?
Equipment access is particularly important for boulder walls because individual stones can weigh hundreds or even thousands of pounds.
Construction can require equipment such as:
- Excavators
- Compact track loaders
- Skid steers
- Material-handling equipment
- Compaction equipment
- Dump trucks or heavy trailers
The equipment needs to reach the work area safely while excavated material moves out and large boulders and aggregate move in.
Narrow side yards, fencing, steep slopes, septic systems, existing landscaping and structures can complicate access.
Unlike smaller landscape materials, large structural boulders can’t simply be carried through a gate by hand.
How Do Spokane-Area Soil Conditions Affect Boulder Walls?
Spokane-area subsurface conditions can change considerably from one part of the region to another.
Spokane Valley contains extensive deposits from the Glacial Lake Missoula floods, including gravel, cobbles, boulders and sand.
Green Bluff commonly has deep, well-drained soils with ashy silt-loam upper layers and increasingly gravelly material below.
Five Mile Prairie and North Spokane can encounter varying combinations of flood deposits, finer sediments, native soils and rock.
Indian Trail and Northwest Spokane include many sloping properties where topography can be as important as soil type.
South Hill and the Latah Creek area can include substantial slopes as well as varying combinations of rock, sand, silt and fine-grained deposits.
Those regional descriptions don’t determine what will be found on a particular property. An on-site evaluation is necessary to understand the excavation, drainage and foundation requirements.
Why Does Slope Affect the Price?
Boulder walls are often constructed specifically because a property has significant elevation change.
A wall may be used to:
- Create a level lawn
- Support a driveway
- Create usable landscape space
- Stabilize a slope
- Create planting terraces
- Support an outdoor living area
- Manage grade changes around a home
The steeper and more complicated the site, the more planning may be required for excavation, equipment positioning, drainage and material handling.
A boulder wall on a hillside may also need to account for what’s above the wall—not merely the soil immediately behind it.
When Does a Boulder Wall Require Engineering?
Height isn’t the only consideration.
Local retaining-wall requirements can depend on the wall’s total height, how that height is measured, the slope around it and whether the wall supports additional loads or “surcharges” such as a driveway, structure or steep slope.
In Spokane County, the commonly referenced four-foot threshold is measured from the bottom of the footing to the top of the wall, not simply from the amount of wall visible above finished grade.
Depending on the project, engineering and permitting can become part of the cost.
Wall & Company evaluates those requirements as part of planning the wall rather than assuming that every boulder wall can be constructed the same way.
Why Is Drainage Important Behind a Boulder Wall?
Water can add substantial pressure behind any retaining structure.
Boulder walls naturally contain openings between individual stones, but that doesn’t eliminate the need to properly manage water and backfill.
Depending on the site, construction can require drainage aggregate, appropriate backfill, grading and additional drainage measures.
The goal is to prevent water from accumulating where it can contribute to movement, erosion or instability.
What Is Included in a Wall & Company Boulder Wall?
Depending on the project, a Wall & Company boulder wall can include:
- Layout and site preparation
- Excavation
- Foundation preparation
- Compacted base material
- Structural boulders
- Equipment for boulder placement
- Individual fitting and positioning
- Drainage aggregate
- Backfill
- Additional drainage where required
- Finish grading
- Cleanup
Engineering and permitting may also be required depending on the wall’s height, location and structural conditions.
Much of this work becomes invisible once the landscaping around the completed wall is finished.
How Much Should I Budget for a Boulder Wall?
For a professionally installed Wall & Company boulder wall in the Spokane area, use $35–$100 per square foot of wall face as a realistic planning range.
That means approximately:
100 sq. ft.: $3,500–$10,000
150 sq. ft.: $5,250–$15,000
200 sq. ft.: $7,000–$20,000
300 sq. ft.: $10,500–$30,000
Larger, taller or more structurally complicated walls can exceed those totals.
The range provides homeowners with a realistic starting budget while leaving the final price to an evaluation of the wall design, site, excavation, access, materials and structural requirements.
Frequently Asked Questions
How much does a boulder wall cost in Spokane?
Wall & Company’s typical planning range is approximately $35–$100 per square foot of wall face.
How much would a 150-square-foot boulder wall cost?
Using Wall & Company’s planning range, approximately $5,250–$15,000.
How is boulder-wall square footage calculated?
Multiply the approximate wall length by its average height. A 50-foot wall averaging three feet high contains approximately 150 square feet of wall face.
Are boulder walls less expensive than block retaining walls?
Not necessarily. Boulder size and sourcing, equipment requirements, site access, excavation, wall height and structural requirements all affect the final cost.
Do boulder walls need drainage?
Yes. Although gaps between boulders can allow some water movement, water and soil still need to be properly managed behind and around the wall.
Can a boulder wall support a driveway?
Potentially, but a wall supporting a driveway is carrying an additional load. That can affect engineering, wall design and construction requirements and needs to be evaluated for the specific site.
Do boulder walls require engineering in Spokane?
Some do. Wall height, footing depth, slopes and additional loads can affect permitting and engineering requirements. The specific project needs to be evaluated rather than relying only on the visible wall height.