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 chisel to remove half of the raised front lip. This allows the next course to be installed on a level surface (Step 1).
• Lay the modified bock perpendicular to another AB unit. This creates the corner. Level, backfill, and compact (Step 1).
• On the next course, remove the opposite half of the lip of an AB unit and position it over the right-angle corner (Step 2).
• On each successive course, simply reverse the position of the modified block to obtain an interlocked corner. Level, backfill, and compact each course.

Video: How to Build an Inside Corner in a Retaining Wall

Outside Corners

AB Corners 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. Always build your walls by starting at the corners and working out.

• Start construction of all walls at the corner. This will keep the block alignment within the 3 in (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).

Video: How to build an outside corner in a retaining wall

Altering AB Corner Blocks for Different Setbacks

AB Corner Blocks are manufactured with a 12° setback. With some minor adjustments, the block for a 6° setback, cut a notch on the shirt side of the 0.75 in (20 mm) deep.

Installing Geogrid on Inside 90° Corners

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

• Cut geogrid to required lengths per the approved plan. A general rule, the length of the geogrid needs to extend a minimum of 25% of the 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 wall heigh is 12 ft (3.7 m), divide by 4 which equals 3 ft (0.9 m).

The length the grid will need to extend past the corner is 3 ft (0.9 m).

Installing Geogrid on Outside 90° Corners

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

• Cut geogrid to the 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.