How to Build a Structural Retaining Wall Step by Step

Table of Contents

• How to Build a Structural Retaining Wall Step by Step
• Planning Your Retaining Wall: Site, Height, and Permits
  • The pre-build checklist
  • When a retaining wall needs an engineer
• Choosing the Best Materials for Retaining Walls
• Tools and Materials Checklist
• Retaining Wall Foundation Depth and Excavation
• Retaining Wall Construction Steps: Laying Courses and Setting Alignment
• Retaining Wall Drainage and Backfill to Prevent Failure
  • How water actually fails a wall
  • The drainage assembly, layer by layer
  • Surface water and the slope above
  • Warning signs of hydrostatic failure
• Book Your Retaining Wall Consultation with Solid Rock Brick
• Frequently Asked Questions

How to Build a Structural Retaining Wall Step by Step

Last Updated: November 1, 2026

Planning Your Retaining Wall: Site, Height, and Permits

Building a retaining wall is a serious structural job. Done right, it holds back soil for decades. Done wrong, it bulges, cracks, and can fail in a single rainy season.

Start by walking the site. Note where the slope is steepest, where water runs during heavy rain, and where buried utilities may sit. Mark the wall line with stakes and string, then measure the height at each end.

The pre-build checklist

Work through this list before you buy a single block:

• Call 811 before you dig (811 Before You Dig). The national Call Before You Dig service routes your request to the local utility operators, who mark buried electric, gas, water, sewer, and communications lines. Digging without marking risks injury, outages, and repair bills.
• Confirm property lines. Pull your survey or plat map and locate easements. A wall built across a property line or inside a utility easement may have to be removed at your expense, and many easements prohibit permanent structures.
• Check setbacks. Local zoning often requires a minimum distance from property lines, sidewalks, and storm drains. Setbacks vary by jurisdiction and by wall height.
• Ask the building department about permit thresholds. Many jurisdictions require a permit once a wall retains more than a set height, or when the wall supports a surcharge such as a driveway, patio, or building. Ask specifically whether your wall needs a permit, a plan review, or a stamped design.
• Identify the surcharge. Anything that adds load within a distance behind the wall roughly equal to the wall height, a driveway, a parked car, a shed, a pool, a slope above, increases the design load and often triggers engineering.

When a retaining wall needs an engineer

Most short landscape walls do not need stamped drawings. Taller walls and walls that hold up a driveway, a building, or a steep slope usually do. Local codes often require engineered designs once a wall passes a set height; check with your building department for the threshold that applies to you.

A structural engineer is also warranted when:

• The wall retains a slope steeper than roughly 1:1 above it, or sits on a slope itself.
• The soil is expansive clay, loose fill, or otherwise weak, or groundwater is present.
• The wall will support a surcharge, a driveway, structure, pool, or heavy equipment.
• The wall is terraced, with one wall above another.
• Frost depth is deep and the wall must resist frost heave.

The engineer's job is to calculate the loads the wall must resist, the weight of the retained soil, any surcharge on top, water pressure if drainage is inadequate, and the resistance of the soil beneath the base, and to specify the block, reinforcement, base width, and drainage details that will carry those loads.

Before you buy any blocks, check these items; the list below shows what each one covers.

Choosing the Best Materials for Retaining Walls

The right material depends on wall height, soil type, and the look you want. Segmental concrete block is a common choice for DIY and mid-height walls. It stacks without mortar and uses a setback design that locks the courses together.

Ask your supplier for blocks rated for your wall height and check that they include a matching cap block and drainage fabric.

Tools and Materials Checklist

Gather everything before you dig. Running out of crushed stone mid-project causes delays and uneven bases. If you would rather have a professional handle the masonry, see our masonry services in Jackson, MS.

• Tape measure and string line
• Stakes and mason's line
• Shovel and spade
• Plate compactor (rented)
• Level (4-foot and torpedo)

Retaining Wall Foundation Depth and Excavation

The foundation is the most important part of the wall. If you also need groundwork for a driveway near the wall, see driveway installation in Jackson, MS for related site work.

A common mistake is building on loose topsoil. Soil that is not compacted settles, and the wall settles with it. Dig down to firm, undisturbed soil whenever you can.

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Retaining Wall Construction Steps: Laying Courses and Setting Alignment

Set the first course carefully. Every course above it depends on it. Place each block on the compacted base, then check it with a level both front to back and side to side.

1. Lay the first course along the string line
2. Level each block and tap it with a rubber mallet
3. Set the next course, offsetting joints like bricks
4. Apply the manufacturer's setback at each course
5. Check alignment with the string line every few blocks
6. Install the cap blocks with construction adhesive

Stop and recheck the level after every two or three courses. Small errors add up quickly at the top of a wall.

Retaining Wall Drainage and Backfill to Prevent Failure

Water pressure causes most retaining wall failures. Soil behind the wall holds water after rain, and that water pushes against the blocks. A good drainage system relieves that pressure. This is the section most DIY guides rush, and it is the one that decides whether the wall stands.

How water actually fails a wall

When water saturates the soil behind a wall and cannot drain, it builds hydrostatic pressure, a horizontal push that grows with depth and with the height of the water table behind the wall. Saturated soil also loses shear strength, so the soil itself becomes heavier and less able to support the wall.

The fix is to give water a fast path out from behind the wall and to keep fine soil from clogging that path.

The drainage assembly, layer by layer

Build the drainage system as you backfill, not after:

1. Filter fabric against the soil. Line the excavation on the soil side with a geotextile fabric. The fabric lets water through but keeps fine soil particles from migrating into the gravel and clogging it. Wrap the fabric over the top of the gravel at the end so soil cannot wash in from above.
2. Drainage aggregate behind the wall. Fill the space between the wall and the fabric with clean, free-draining gravel, washed crushed stone, not crusher run or clay-heavy fill. The gravel column gives water a vertical path down to the drain pipe.
3. Perforated drain pipe at the base. Lay a perforated pipe in the gravel at the base of the wall, holes down or per the manufacturer's direction, sloping toward an outlet. Slope matters: a pipe that runs flat or backward holds water instead of releasing it.
4. A defined outlet. Daylights the pipe at a low point, a storm drain, or a dry well. A drain pipe with no outlet is a bathtub. Confirm the outlet is legal and does not discharge onto a neighbor's property.
5. Backfill in compacted lifts. Backfill behind the drainage gravel in layers, commonly 6 to 8 inches per lift, and compact each lift. Over-compacting directly against the wall can push it out of line, so keep compaction equipment a safe distance back and compact by hand near the blocks.

Surface water and the slope above

Drainage behind the wall is only half the job. Water running down the slope above the wall adds load and erodes soil. Grade the surface above the wall to slope away from it, and consider a swale or surface drain to intercept runoff before it reaches the wall. Keep downspouts and gutter outlets from discharging near the wall.

Warning signs of hydrostatic failure

Inspect the wall after heavy rain and at least once a season. Early warning signs include:

• Bulging or leaning, especially near the middle or at the base.
• Soil or water seeping through the face of the wall.
• Settled or tilted cap blocks.
• Cracks that widen over time.
• Water pooling behind the wall or at its base after rain.

Any of these means water is not leaving the wall system fast enough. Address the drainage before the movement gets worse, a small repair now is cheaper than a rebuild later.

Book Your Retaining Wall Consultation with Solid Rock Brick

Building a structural wall takes planning, the right materials, and careful work at every course. If you want a professional to handle the job, book a retaining wall consultation with Solid Rock Brick. Pricing depends on wall size, materials, and site conditions, so contact us for a quote.