Consult and Engineer > 3' Tall

Segmental Retaining Wall Installation Guide

This guide covers the key steps, terminology, and engineering considerations for planning and installing segmental retaining walls (SRW). Always consult a qualified geotechnical or structural engineer for walls taller than 4 feet, walls situated in poor soils, walls supporting a driveway, or any application requiring a stamped design.

Safety Note: Always wear appropriate safety equipment including safety glasses and respirators when splitting, cutting, or hammering units.

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1. Stake Out the Wall

• Have a surveyor stake out the wall placement and verify locations with the project supervisor
• Verify the proposed height of the wall against approved plans

2. Excavation

• Account for the leveling pad, lines, grades, and geosynthetic reinforcement material
• The trench for the leveling pad should be at least 2 feet wide and a minimum of 1 foot deep — enough to bury the first course below grade, plus 6 inches for the leveling pad
• Ensure a minimum of 8 inches (or 10% of finished wall height, whichever is greater) is below grade
• If the planned grade changes along the wall front, the leveling pad may need to be stepped (typically 8-inch increments) — always start at the lowest level and work upward

3. Leveling Pad

• Use a compactible base material of ¾-inch minus with fines
• Compact the aggregate, making sure it is level from front to back and side to side — mist lightly with water before compaction if needed

4. Base Course

This is the most important step in the installation process.

• Begin laying block at the lowest elevation of the wall, removing the rear lip of each block before placing
• Place first block level front to back and side to side; lay subsequent blocks the same way
• Place blocks side by side, flush against each other, ensuring full contact with the leveling pad
• Place soil in front of the base course and compact — base course should be buried; fill and compact after each course

5. Constructing Subsequent Courses

• Fill cores and voids between blocks with ¾-inch clean drainage aggregate before laying the next course — clear any debris off the top of the blocks
• Place the second course on top of the base course maintaining running bond — pull each block forward as far as possible to ensure correct setback
• Backfill with drainage aggregate directly behind the block, adding 6 to 8 inches at a time — add soil fill behind the aggregate
• Compact before the next course is laid — do not drive heavy equipment near the wall; self-propelled compaction equipment should not be used within 3 feet of the back of the wall
• You may need partial units to maintain running bond — use a masonry blade circular saw with safety glasses and protective equipment when cutting
• If the wall is on an incline, do not slope the blocks — step them up so they remain consistently level
• Use a string along the back edge of the block to check for proper alignment

6. Drainage Design

Good drainage is critical to the long-term performance of a segmental retaining wall. Water collected from behind the wall must be able to drain down and away — either at the end of the wall, via a carrier drain, or through drainage weep holes.

• Each project is unique — grades on site determine the drainage pipe elevation; place 4-inch perforated pipe so water drains down and away from the wall into a storm drain or daylight just above grade
• Fill in the area behind the blocks with clean drainage aggregate, at least 1 foot from the wall — you may need to place and backfill several courses to achieve proper drainage level
• Drainage pipes should be spaced no more than every 50 feet and at low points of the wall — pipes must stay clear of regional fill soil
• First Course (walls longer than 50 ft): Drainage weep holes must be installed through the wall face, no more than 50 feet apart — remove 2 inches off the front of two adjacent blocks to provide sufficient space for drainage to exit through the face
• Build remaining courses using standard construction techniques

7. Compaction

• Shovel the backfill soil behind the drainage aggregate and compact the backfill with a hand-operated compactor
• Make sure the grade is level with or slightly below the top of the base course
• Continue to fill and compact after each course is laid

8. Reinforcement (If Required)

Geosynthetic reinforcement is recommended for walls taller than 4 feet or walls situated in poor soils, supporting a driveway, etc. Consult an engineer for design assistance.

• Check the wall construction plan to determine which courses will need reinforcement — clean any debris off the top layer of blocks; measure and cut reinforcement to the design length
• The reinforcement has a design strength direction, which must be laid perpendicular to the wall
• Place the front edge of the material on the top course, 1 inch from the face of the block
• Apply the next course of blocks to secure in place — to keep from wrinkling, pull the reinforcement taut and pin the back edge in place with stakes or staples
• Add drainage aggregate behind the blocks, then add the backfill soil and compact
• Correct placement ensures you maximize the connection strength and keep the batter consistent — a minimum of 6 inches of backfill is required prior to operating vehicles on the reinforcement

9. Capping a Wall

• Always start capping from the lowest elevation — if the wall elevation changes, caps can be stacked where the wall steps up
• Lay caps at the elevation change and work back toward the previous step up — cut caps with a diamond-blade saw to fit as needed
• Carefully glue caps in place with a high-strength concrete adhesive

Cap Configurations

• Straight Wall: Alternate short and long cap faces — caps have a recess on the bottom to accommodate the locator, always laid with recess facing downward
• Outside Curves: Lay cap units side by side and cut at least every other cap to produce a uniform look — start with the long side of the cap facing out and adjust to the radius
• Inside Curves: Lay caps side by side with the short side facing out — in most circumstances, making two cuts on one cap and not cutting the cap on either side produces the most pleasing look
• Corners: On a 90° corner wall, corner caps need to be saw-cut to achieve a 45° mitered corner
• Finishing: After layout is complete and caps are saw-cut to size, carefully glue caps in place using exterior-grade concrete adhesive

10. Running Bond

Proper installation requires that running bond be maintained — this occurs when blocks are centered over the vertical joints of the previous course, adding to wall stability and making the wall aesthetically beautiful.

• Straight walls: Maintain running bond throughout
• Outside curved walls: Any wall that is not perfectly straight will eventually run off bond — when this happens, skip a block position and place the next block into the next place where it is back on bond; measure the remaining gap and cut or split a block to fit
• Partial units must not be less than 8 inches long and should not be placed directly on top of each other — if the gap is larger than the length of one block, divide the measurement by two and put two partial units in place
• Tip: It may be possible to run the off-bond block into the soil bank to avoid cutting partial units

11. Corners

Inside 90° Corners

• Base Course: To create an inside 90° corner, begin by placing a block at the corner, then lay a second block perpendicular to the first and continue laying the rest of the base course working from the corner out
• Additional Courses: Place all blocks in a running bond along one side of the corner — once the second course of one wall is established, begin the second course of the adjacent wall; several blocks away from the corner, pull blocks in a running bond back toward the corner until the gap becomes less than a full unit; spot units may be required to maintain running bond
• Subsequent Courses: Block placement in the corner must alternate in direction with each succeeding course — the locator of the block being overlaid within the corner should be removed using a hammer and chisel; these units should be glued in place using concrete adhesive

Outside 90° Corners

• Base Course: Begin by placing a corner unit and working from the corner unit outward
• Next Course: Lay a corner block perpendicular to the one below and give the block in place with concrete adhesive — two or three blocks away from the corner, lay full blocks maintaining running bond back toward the corner; corner blocks lay back toward the corner block, leaving space for the final split units to complete the course
• Use split units immediately adjacent to the corner block to complete the course — continue to alternate the corner unit orientation with each course and always use concrete adhesive on all corner units and split units
• Always maintain running bond

12. Curves

Calculating the Radius

Check the wall plan to determine the radius of the base course — this will be the smallest radius in the wall and must not be less than the minimum for the block system used.

Quick formula for base course radius:

1. Add ¾ inch to the setback of the block used — multiply that by the number of courses in the finished wall
2. Subtract the result from the radius of the top course — this equals the approximate radius of the base course
3. To determine the radius for the front edge of the trench, subtract 6 inches from the approximate radius of the base course

Laying Out the Trench

• Drive a stake into the ground at the desired radius point of the curve — attach a string and rotate it in an arc at the desired length to mark the curve in the soil; dig the trench

Inside Curves with Reinforcement

• Most retaining walls are designed assuming 100% reinforcement coverage — when building an inside curve the reinforcement will fan out, producing slight gaps; additional lengths of reinforcement are used to fill those gaps on the next course of blocks
• Cut reinforcement to the lengths specified in the wall plan — lay segments within 1 inch of the face of the wall, with the strength direction perpendicular to the wall face; avoid overlapping the reinforcement by separating each section
• The minimum inside radius varies by product — check product specifications

Outside Curves with Reinforcement

• When building an outside curve the reinforcement will have gaps, and the back edges don't overlap — to ensure 100% coverage, additional lengths of reinforcement are used to fill those gaps on the next course of blocks
• Cut reinforcement to the lengths specified in the wall plan — lay sections within 1 inch of the face of the wall; avoid overlapping the reinforcement by separating each section
• Each product has a unique minimum outside radius — check product specifications

13. Finish Grade & Surface Drainage

• Protect the wall with a finished grade at the top and bottom — ensure proper water drainage away from the wall; use a mixture of soil with low permeability and seed or plant to stabilize the surface
• Consult the wall design engineer if water may be draining toward the wall — it needs to be designed to divert water away from the wall; this will minimize water seeding into the soil and drainage aggregate behind the wall

14. Site Cleaning & Restoration

• Brush off the wall and clean up any debris left from the construction process
• Notify the job superintendent in writing of the completion and that it is ready for final inspection and acceptance
• Planting vegetation in front and on top of the wall will help reduce the chance of erosion
• Following these best practices for construction will ensure the success of your segmental retaining wall — these instructions are meant as general guidelines; site-specific conditions may require additional installation requirements
• For walls over 4 feet high, have compaction tested by a qualified geotechnical engineer

Industry & Regulatory References

• National Concrete Masonry Association (NCMA) – SRW design manuals and technical bulletins
• Interlocking Concrete Pavement Institute (ICPI) – Installer resources and technical guidance
• ASTM International – Standards for segmental retaining wall units (ASTM C1372)

*Special

Special Terms and Conditions for Special Order Materials

Special Orders may have Mold Charges, Set-Up Charges, and Add-On Fees.

Special Order Shapes

• 5 Cube Minimum for the designated Standard Color Offering
• Orders may not be cancelled once manufacturing begins
• Delivery to the job-site is to begin within 30 days after receipt on our yard, and 100% of the materials ordered must be delivered no later than 90 days after receipt on our yard
• Purchaser is responsible for determining all quantities
• Purchaser is required to pay for all materials ordered; if product comes on a Pallet you will be charged for a pallet
• 50% Deposit may be required at time of ordering
• Remaining 50% is due prior to shipment from manufacturer

White/Yellow Reflective Pavers

N/A — No longer available

Add-On Fees

Sizing Guide

Understanding paver specs helps you order the right product and calculate exactly what you need for your project.  Each product's packaging info is listed in your product descriptions.

Nominal vs. Actual Size The size listed in a product name (e.g., 4"x8") is the nominal size — the working dimension including a standard joint gap. The actual size is the physical measurement of the stone itself, which is slightly smaller. Both are listed on each product page.

Thickness & Use Case

• 3/4" (20mm) Porcelain — Residential & Commercial pedestrian & light vehicular
• 1" (25.4mm)  — Residential & Commercial pedestrian & light vehicular
• 1-5/8" (41.275mm) — Residential & Commercial pedestrian
• 2-3/8" (60mm) — Residential & Commercial pedestrian & light vehicular
• 2-1/4" — Residential & Commercial pedestrian & light vehicular
• 3-1/8" (80mm) — Commercial pedestrian & light vehicular
• 4" (100mm) — Heavy Industrial & commercial vehicular

Coverage & Pallet Coverage tells you how many square feet one pallet covers. To estimate your order: divide your total square footage by the coverage number, then round up. Always add 10% for cuts and waste.  Sales are sold in full pallet quantities.

Mix Ratios (3-Piece Systems) Some products ship as a pre-mixed pallet of multiple stone sizes. The mix ratio (e.g., 17/33/50%) reflects the proportion of each size per pallet — you cannot order individual sizes separately.

20mm Porcelain  pavers ship at 20mm thickness.

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