Retaining Wall Corners    

Corners with AB Collection   

Corners typically require custom cutting of the blocks. Try to design curves instead. Angled retaining walls are not as stable as curved retaining walls, so whenever possible we recommend using curves instead of corners for a smooth flowing look to your landscape. If you need to use corners in your design, follow the instructions below:

Building Allan Block Walls with Corners

Inside Corners

AB Blocks are easily modified to build inside corners. To construct an inside corner, you will remove part of the raised lip on one block on each course.

• Use a saw with a diamond blade or a chisel to remove half of the raised front lip. This allows the next course to be installed on a level surface.
• Lay the modified block perpendicular to another AB unit. This creates the corner.
• On the next course, remove the opposite half of the lip of an AB unit and position it over the right angle corner.
• On each successive course, simply reverse the position of the modified block to obtain an interlocked corner.
• Cut caps at 45 degree angles to complete the inside corner and give the retaining wall a custom finished look. It's a good idea to secure caps with a high strength construction adhesive once they are all cut.
  More options for finishing your retaining wall.

Cut caps at 45 degree angles

Outside Corners

AB Corner Blocks are used to build outside 90° corners. To construct an outside corner, you will use an AB Corner Block on every course, alternating a right and left hand corner for each course.

• Start construction of all walls at the corner. This will keep the block alignment within the 75 mm overlap required.
• Place an AB Corner Block at the corner. Place AB Blocks to build the base course working out from the corner in both directions (Step 1). Level, backfill and compact.
• On the 2nd course place an alternating AB Corner Block. Again work out from the corner in both directions. Level, backfill and compact (Step 2).
• Repeat this procedure, alternating every other course with AB Corner Blocks. Leveling, backfilling, and compacting as the wall grows (Step 3).
• Cut caps at 45 degree angles to complete the inside corner and give the retaining wall a custom finished look. It's a good idea to secure caps with a high strength construction adhesive once they are all cut.
  More options for finishing your retaining wall.

Altering AB Corner Blocks for Different Setbacks

AB Corner Blocks are manufactured with a 12° setback. With some minor adjustments, the blocks can be modified to work with any setback. To modify the block for a 6° setback, cut a notch on the short side of the block 20 mm deep.

For a 6° setback, make a horizontal cut 20 mm deep. Remove this piece after cut is made

Corners with Geogrid

Installing Geogrid on Inside 90° Corners

On inside corners additional geogrid is required to extend past the end of the retaining wall, 25% of the completed wall height (H/4).

• Cut geogrid to required lengths per the approved plan. As a general rule the length of the geogrid needs to extend a minimum of 25% of the retaining wall height past the end of the inside corner.
• Install the layer of geogrid with the geogrid extending past the inside corner.
• Alternate the next layer of geogrid to extend the past the inside corner in the opposite direction.

Example

Finished retaining wall height is 3.7 m, divide by 4 which equals 0.9 m. The length the grid will need to extend past the corner is 0.9 m.

Installing Geogrid on Outside 90° Corners

Geogrid must always be installed with its strong direction perpendicular to the face of the retaining wall. To accomplish this with 90° outside corners:

• Cut geogrid to required lengths per the approved plans
• Install geogrid to the outside corner with the roll direction running back into the excavated site.
• On the next course of block, lay the next layer of grid perpendicular to the previous layer.