6459 State Highway 23
Oneonta, NY 13820
607-432-6641 • Fax 607-433-6284
65 State Route 369
Port Crane, NY 13833
607-648-7051 • Fax 607-648-7050
Oneonta Block Company

Retaining Wall Installation Tips - See Free Standing Wall Installation Tips

Corners / Curves
Steps
Miscellaneous
Drainage
Special Applications
Reinforcement

Retaining Wall Basics

Segmental retaining walls typically fall into one of two categories.

Gravity Retaining Wall
The first category - a gravity wall - is a retaining wall that does not use soil reinforcement. A gravity wall has height limitations specific to each product. An advantage of this type of retaining wall is that it requires a smaller work area behind the wall. A gravity wall relies on the weight and setback of the block to resist the soil forces being exerted on the wall.

Geosynthetic - Reinforced Retaining Wall
The second category is a geosynthetic - reinforced wall, which needs to be designed by a qualified engineer. With a reinforced retaining wall there are (theoretically) no height limitations, and they are used in larger applications. They require more work area behind the structure. The block of soil is stabilized by introducing reinforcement layers into the soil mass behind the facing units. The larger the stabilized soil mass, the more soil can be retained or held back. The geosynthetic reinforcement in the soil extends past the theoretical failure plane and serves to create a large, rectangular mass of block and soil, restraining the retained soil.

Basic Installation

The following installation instructions apply to Anchor retaining wall products that feature a rear lip. Where there are variations, the appropriate information has been noted.


Excavation


Leveling Pad Compaction


Construction of the Next Course


Core Fill


Filter Fabric


Drain Tile


Drain Aggregate


Compaction

Stake out the Wall
  • Have a surveyor stake out the wall's placement. Verify the locations with the project supervisor.
Excavation
  • Excavate for the leveling pad to the lines and grades shown on the approved plans and excavate enough soil behind the wall for the geosynthetic reinforcement material. The trench for the leveling pad should be at least 12 inches wider than the block you are installing and 6 inches deeper than the height of the block.
Leveling Pad
  • An aggregate leveling pad is made of compactable base material of 3/4-inch minus (with fines).
  • The pad must extend at least 6 inches in front of and behind the first course of block and be at least 6 inches deep after compaction.
  • If the planned grade along the wall front will change elevation, the leveling pad may be stepped up in 6-inch increments to match the grade change. Start at the lowest level and work upward whenever possible.
  • Compact the aggregate and make sure it's level front to back and side to side. Mist lightly with water before compaction.
Base Course
  • This is the most important step in the installation process. Bury the base course of block.
  • Begin laying block at the lowest elevation of the wall. Remove the rear lip of the block by hitting from the back so that it will lie flat on the leveling pad.
  • Place first block level, front to back and side to side; lay subsequent blocks in same manner.
  • Place the blocks side by side, flush against each other, and make sure the blocks are in full contact with the leveling pad.
  • If the wall is on an incline, don't slope the blocks; step them up so they remain consistently level.
  • Use stringline along back edge of blocks to check for proper alignment.
  • For multi-piece products, use the largest unit, 18 inches wide, for the base course.
Construction of the Next Course
Diamond and Diamond Pro
  • Clean any debris off the top of the blocks.
  • Place the second course of blocks on top of the base course. Maintain running bond. Pull each block forward as far as possible to ensure the correct setback.
  • Backfill with drainage aggregate directly behind the block, adding 6 inches at a time followed by proper compaction.
  • Add soil fill behind the aggregate. Compact before the next course is laid.
  • Don't drive heavy equipment near the wall. Self-propelled compaction equipment should not be used within 4 feet of the wall.
  • You'll need partial units to stay on bond. A circular saw with a masonry blade is recommended for cutting partial units. Use safety glasses and other protective equipment when cutting.
  • If you are using a block with cores that should be filled, fill prior to laying the next course
Highland Stone
  • Follow instructions as noted above.
  • You can install this product using any combination of blocks.
  • Keep the wall bond by placing units in a staggered relationship to the course beneath.
  • For best results, use a filter fabric, which should be placed directly behind the wall extending from the bottom of the base course to the middle of the top course. This will minimize material coming through the rough-hewn face texture of these products. A non-woven, 4 to 6 ounce fabric is recommended.
Drainage Design
  • Each project is unique. The grades on your site will determine at what level to install the drain tile.
  • Place the drain tile as low as possible behind the wall so water drains down and away from the wall into a storm drain or to an area lower than the wall.
  • Fill in the area behind the blocks with drainage aggregate, at least 12 inches from the wall.
  • You may need to place and backfill several courses to achieve the proper drainage level.
  • Cover the drain tile with a geotextile sock which acts as a filter. The drain tile outlet pipes should be space not more than every 50 feet and at low points of the wall. In order for the drainage aggregate to function properly, it must keep clear of regular soil fill.
Compaction
  • Shovel the backfill soil behind the drainage aggregate and compact with a hand operated compactor.
  • Make sure the aggregate is level with or slightly below the top of the base course.
  • Place soil in front of the base course and compact. Base course should be buried.
  • Continue to fill and compact.
Reinforcement (if required)
  • Geosynthetic reinforcement is recommended for walls taller than 4 feet or walls situated in poor soils, supporting a driveway, etc. Consult a qualified engineer for design assistance.
  • Check the wall construction plan for which courses will need reinforcement.
  • Clean any debris off the top layer of blocks.
  • Measure and cut the reinforcement to the design length in the plans.
  • 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, 2 inches from the face of the block.
  • Apply the next course of blocks to secure it in place.
  • To keep it 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 soil and compact it.
  • Remember - place the front edge of the reinforcement on top of the block, making sure it's within 2 inches of the face of the block. Correct placement ensures that 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. Avoid sudden turning or braking.
Finish Grade and Surface Drainage
  • Protect the wall with a finished grade at the top and bottom.
  • To ensure proper water drainage away from the wall, use 6 inches of soil with low permeability. This will minimize water seeping into the soil and drainage aggregate behind the wall.
Site Cleaning and Restoration
  • Brush off the wall and pick up any debris left from the construction process.
  • Notify the job superintendent in writing of the project's 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.
SAFETY NOTE: Always use appropriate equipment, including safety glasses or goggles and respirators, when splitting, cutting or hammering units.

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 out the rest of the base course working from the corner out. Make sure to construct the base course according to standard site prep and installation procedures described earlier.

The Next Course
On the second course, place all blocks on bond along one side of the corner. Once the second course of one wall is established, begin the second course of the adjacent wall. Split units* maybe required on this wall to maintain running bond.

*To split a block, use a hydraulic splitter or split manually by using a hammer and chisel to score the block on all sides. Pound the chisel on the same line until the block splits. If partial unit sides are not exposed, use a circular cut-off saw with a masonry blade to achieve a tighter fit.

Block placement in the corner should alternate direction with each succeeding course.


Outside 90° Corners


Outside Corner

Base Course
To build an outside 90° corner, begin by splitting a large unit in half. Place this unit with both split faces out at the corner. Remove the lip so that the block lies flat. Then lay the rest of the base course working from the corner block out.

Second Course
Begin the second course with the other half of the large unit. Place the second and third blocks on either side of the corner unit. Once the corner unit is in position, glue block in place with a concrete adhesive. Continue to alternate the corner unit orientation with each course and always use a concrete adhesive.

Use split units* as necessary to maintain running bond.

*To split a block, use a hydraulic splitter or split manually by using a hammer and chisel to score the block on all sides. Pound the chisel on the same line until the block splits. If partial unit sides are not exposed, use a circular cut-off saw with a masonry blade to achieve a tighter fit.


Inside Curves


Inside Curve

Calculate 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.

Base Course
Begin by driving a stake into the ground at the desired center of the curve. Attach a string and rotate it in a circle around the stake to mark the radius in the soil. Align each block face with the radius curve and ensure level placement from side to side and front to back.

Additional Courses
On each course, the lip of each block must be in contact with the back of the units below to ensure structural stability. The setback of the block will cause the radius of each course to gradually increase and eventually affect the running bond of the wall. To maintain proper running bond, use partial units as needed. Once a split unit is cut to size, glue in place with a concrete adhesive.


Outside Curves

Outside Curve

Calculate the Radius
When building an outside radius curve, begin by calculating the radius of the top course. This will be the smallest radius in the wall and must not be less than the minimum radius for the block system used.

Here is a rule of thumb used to calculate the approximate radius of the course: add 1/4 inch to the setback of the block used. Multiply that amount by the number of courses in the finished wall. Then subtract the result from the radius of the base course. This number equals the calculated radius of the top course.

Example: The setback of Highland Stone is 1 1/8".
The wall is 8 courses high. The radius of the base course is 6 feet.
1 1/8" + 1/4" = 1 3/8" x 8 courses = 11"6' - 11" = 5'11" calculated radius of the top course.

Base Course
Drive a stake into the ground at the desired center of the cure. Attach a string and rotate it in a circle around the stake to mark the radius in the soil. Align the back of the block with the radius curve and ensure level placement from side to side and front to back.

Additional Courses
On each course, the lip of each block must be in contact with the back of the units below to ensure structural stability. The setback of the block will cause the radius of each course to gradually decrease and eventually affect the running bond of the wall. To maintain proper running bond, use partial units as needed. Once a split unit is cut to size, glue in place with a concrete adhesive.


Standard Step

These construction drawings feature step units. Caps or pavers can be used for treads. Check local building codes for any tread depth standard.

Base Course
Thoroughly compact the leveling pad. Lay out the base course according to the wall design. Place step units first, working from the center to each side. Remember, it is very important to backfill and compact behind and along the sides of each course of step units.

First Step Course
Place the first course of step units directly on top of the base course so there is no setback. Stagger them from the previous course and glue in place.

Second Step Course
Add the second course of steps, staggering them from the previous course to maintain running bond. Overlap the previous course by 2 inches and glue to lower course.

Second wall course
Build the second course of the wall.

Third Step Course
Beginning in the center, add the third course of steps, lining up the units with the first course. Overlap 2 inches and glue in place.

Third Wall Course
Build the third wall course of the wall. Repeat these steps until the wall is finished.


Graceful curves enhance the appearance of a step area.
Elevation

Drainage tip: Drain pipe can be placed behind the lowest step units at grade or behind each wall adjacent to the steps.


Step

Step

These construction drawings feature step units. Caps or pavers can be used for treads. Check local building codes for any tread depth standards.

Base Course
Thoroughly compact the leveling pad. Lay out the base course according to the wall design. Place step units first, working from the center to each side. Remember, it is very important to backfill and compact behind and along the sides of each course of step units.

First Step Course
Place the first course of step units directly on top of the base course so there is no setback. Stagger them from the previous course and glue in place.

Second Step Course
Add the second course of steps, staggering them from the previous course to maintain running bond. Overlap the previous course by 2 inches and glue to lower course.

Second Wall Course
Build the second course of the wall.

Third step course
Beginning in the center, add the third course of steps, lining up the units with the first course. Overlap 2 inches and glue in place.

Third wall course
Build the third course of the wall. Repeat these steps until the wall is finished.

Drainage Tip: Drain pipe can be placed behind the lowest step units at grade or behind each wall adjacent to the steps.


Capping a Wall

Straight Wall
Caps are trapezoidal and must be laid alternatively short and long cap faces for a straight line. Always start capping from the lowest elevation.

Outside Curves
Lay out the 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 cap units side by side with the short side facing out. In most circumstances, making two cuts on one cap and then not cutting the cap on either side produces the most pleasing look.

Corners
On a 90° corner wall, the corner caps need to be saw-cut to achieve a 45° mitered corner.

Stepping Up Caps
If a fall elevation changes, caps can be stacked where the wall steps up. Begin laying caps at the lowest elevation change and work your way back toward the previous step up. Split a cap unit to create a rough face on the exposed side. Place the half unit directly on top of the capped portion of the wall with all three split faces exposed.

Finishing
After layout is complete and caps are saw-cut or split to size, carefully glue with a concrete adhesive.


Running Bond

Running Bond

Straight Wall
Proper installation of any Anchor Retaining wall requires that running bond be maintained. Running bond occurs when the blocks are centered over the vertical joints of the previous course. This adds to wall stability and makes your wall system aesthetically beautiful.

Curved Wall
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 a block to fit.

Once the partial unit is in place, glue with a concrete adhesive. Partial units should not be less than 5 inches and should not be placed directly on top of each other. If the gap is larger than then length of one block, divide the measurement by two and put two partial units in place.


Stepping Up the Base

Lowest Point
Walls built on a sloping grade require a stepped base. Begin excavation at the lowest point and dig a level trench into the slope until it is deep enough to accommodate the base material and one entire block.

Step Up
At this point, step up the height of one block and begin a new section of base trench. Continue to step up as needed to top of slope. Always bury at least one full unit at each step.

Stepping Up the Base

Abutting Existing Structure

Abutting Existing Structure

First Course
Begin with the first block next to the wall and place first course. Place filter fabric behind the first two large units and extend it 2 feet along the existing structure.

Second Course
Build second course with standard installation techniques. A split unit is shown, but may not be necessary in every installation. Extend filter fabric to the top edge of the final course. A rubber membrane can be placed between the units and a non-concrete wall to prevent moisture damage to the structure.


Daylighting Drainage

First Course
To daylight drain pipes through a wall face, place the drain pipes on compacted leveling pad aggregate placed behind the first course. Space these drains not more than 50 feet apart. Split 2 inches off the front of two adjacent large units to provide space for the drain pipe to exit through the face.

Next Course
Build this and remaining courses using standard construction techniques.

Tip: To daylight through slope, see Drainage Swales.

Daylighting Drainage

Drainage Swales

The design and performance of most retaining walls are based on keeping the reinforced zone relatively dry. Appropriate drainage swales to help control water should be designed in the wall construction plan.


Fences

Know the dimensions of the fence to determine the placement of the sleeves. Provide at least 1 inch clearance between the inside of the sleeve and the outside of the post, and allow for mortar and grout. Install the sleeves according to the wall plan during the construction of the wall.

If the fence is at least 3 feet behind the wall, generally no additional reinforcement is required. If the fence is installed within 3 feet, there may be some load transferred to the wall from wind, snow or pedestrians. Additional reinforcement around the fence sleeves may be needed.

Grout the fence post into the sleeve after the wall is built.

Tip: Download Sleeve-It for more information on fence sleeves. Download Installation for additional information on installing Sleeve-It fence sleeves.

Fences

Terraces

Terrace

Independent Terraced Walls
For each wall to be independent of others, it must be built using a 2:1 ratio--the upper wall must be built a distance away from the lower wall of at least twice the height of the lower wall. In addition, the upper wall must also be equal to or less than the height of thee lower wall. Exceptions to this general rule include weak soil conditions, or where slopes exist above, below or between wall locations. For example, if the lower terrace is 4 feet tall, the distance between the terraces must be at least 8 feet and the upper wall must not be higher than 4 feet.

Drainage is vital to maintaining stable, long-lasting terraced walls. Drain tile must be installed so that the water is directed around or under the lower wall (never place the drain tile outlet for the upper wall above or behind the lower wall).

For more detailed information about drainage, see Daylighting and Drainage Swales.

Dependent Terraced Walls
When the distance between the lower and upper walls is less than twice the height of the lower wall, the walls become structurally dependent on each other. In this situation it is important to take global stability into account, incorporating additional reinforcement--and longer layers--into the wall plan. In addition, structurally dependent walls require even more excavation, backfill and time. So plan ahead. Be sure to check the wall plan for specific requirements. For structurally dependent walls, consult with a qualified engineer.


Water Applications

Base Course
Place a filter fabric with extra length in front of the wall.

Install leveling pad and the base course of block, including drain tile and drainage aggregate. Wrap the extended filter fabric up along the face of the base course. Place soil fill in front of the wall and compact. Install another section of filter fabric in front of the wall to protect against erosion. Cover the fabric with a minimum of 3 inches of sand. Install larger stones such as riprap to hold it in place.

Next Course
Continue constructing the wall. Drainage is vital. To prevent clogging of the drainage aggregate and drain tile by fine-grained soils, a geosynthetic filter fabric is installed to separate the drainage aggregate from the reinforced soils.

Additional Courses
Continue these steps until the wall is complete. The last section of filter fabric should cover the drainage aggregate and run up against the back of the top course of block. Add fill soil and compact.

Numerous issues, including wave or ice impact, erosion or scour in front of the wall, and ice uplift of the wall must be considered in the use of water applications of segmental retaining walls.

For more information, consult with a qualified engineer.


Water applications are a great way to get more use from a property.


Inside 90° Corners with Reinforcement

First Course with Geogrid
To install reinforcement on an inside 90° corner, begin by checking the wall plan to determine reinforcement lengths and elevations. Cut reinforcement to the lengths shown in the wall plan, paying attention to the reinforcement strength direction.

Measure this distance from the front of the adjoining wall, begin the grid placement here. Make sure the grid is placed within 2 inches of the face of the wall and runs along the back of the adjoining wall.

Example: If overall wall height is 8 feet, the reinforcement extension would be 2 feet.

Place the next section of reinforcement on the adjoining wall. The reinforcement should not overlap and should lie flush with previously placed sections. Once reinforcement is in place, the next courses of block can be installed.

Second Course with Geogrid
The first section of grid on this course is placed using the same formula that determines placement in front of adjoining wall.

Alternate the reinforcement extension on each course where reinforcement is required.

Place the next section of reinforcement on the adjoining wall. The reinforcement should not overlap and should lie flush with previously placed sections. Once reinforcement is in place, the next courses of block can be installed.


Outside 90° Corners with Reinforcement

Begin by checking the wall plan to determine reinforcement lengths and elevations. Lay a section of reinforcement near the corner of the wall, ensuring that it's placed within 2 inches of the face of the block and running along the back of the adjoining wall.

Lay the next course of block, backfill and compact. When installing the next section of reinforcement, place within 2 inches of the face of the block and running along the back of the adjacent wall.

Outside Corner with Reinforcement


Inside Curves with Reinforcement

First Course with Reinforcement
Most retaining walls are designed assuming 100% coverage of the reinforcement. When building an inside curve, the back edges of the reinforcement will fan out slightly, producing gaps. In order to ensure 100% coverage, additional lengths of reinforcement are used to fill those gaps on the next course of blocks. Don't overlap the grid on one course to avoid slippage.

Cut reinforcement to the lengths specified in the wall plan. Lay segments of reinforcement within 2 inches of the face of the wall, making sure that the strength direction of each section is perpendicular to the wall face.

Next Course
Place the next course of blocks, marking the backs of blocks to identify the middle of unreinforced areas. Backfill and compact. Center subsequent sections of reinforcement on the marked blocks to ensure full reinforcement coverage. Repeat this procedure throughout the construction of the radius curve when reinforcement is required.

Minimum Inside Radius
Windsor Stone4 feet
Diamond Beveled Face4 feet
Diamond Straight Face8 feet
Diamond Pro Straight6 feet
Diamond Pro Beveled4 feet
Diamond Pro Stone Cut4 feet
Highland Stone (Using all 3 widths)8 feet

Inside Curve with Reinforcement

Outside Curves with Reinforcement

First Course with Reinforcement
Most retaining walls are designed assuming 100% coverage of the reinforcement. When building an outside curve, the block edges of the reinforcement will have gaps so that the back edges don't overlap. In order to ensure 100% coverage, additional lengths of reinforcement are used to fill those gaps on the next course of blocks. Don't overlap the grid on one course to avoid slippage.

Cut reinforcement to the lengths specified in the wall plan. Lay sections of the reinforcement within 2 inches of the face of the wall with the strength direction perpendicular to the wall face. Avoid overlapping the reinforcement by separating each section. Place the next course of blocks, marking the backs of blocks to identify unreinforced areas. This step is important because when this course is backfilled, it is impossible to locate the unreinforced areas.

Next Course
Place the next course of blocks, marking the backs of blocks to identify unreinforced areas. This step is important because when this course is backfilled, it's impossible to locate the unreinforced areas. use the marked blocks as a guide, placing subsequent sections of reinforcement to overlap the gaps left on the previous course. This will ensure total reinforcement coverage. Repeat this procedure throughout the construction of the radius curve when reinforcement is required.

Minimum Outside Radius
Windsor Stone2 feet
Diamond Beveled Face2 feet
Diamond Straight Face4 feet
Diamond Pro Straight4 feet
Diamond Pro Beveled4 feet
Diamond Pro Stone Cut7 feet
Highland Stone (Using all 3 widths)4 feet

Outside Curve with Reinforcement