Modifying Retaining Wall Blocks and Capstones

SAFETY FIRST: Always wear safety glasses when splitting or cutting concrete retaining wall blocks. A dust mask is recommended when cutting blocks.

• Use a masonry saw with a diamond cutting blade or a metal chop saw with a dry cutting diamond blade.
• NOTE: Masonry saws and metal chop saws are available for rental at most retail centers.

Standard units 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. See full details here.

• 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.

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. See full details here.

• Cut caps at 45° angles to complete inside or outside corner caps and give the 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° angles

Allan Block's patented design allows for easy installation of both inside and outside curves. Most curves can be built with no cutting involved. See full details here.

Inside Curves

• To build a flowing inside curve, butt the block end to end to match the smooth curve required on the project. Try to keep spacing consistent between the backs of the blocks.

Outside Curves

• To build smooth outside curves, remove one or both of the "wings" from the back of the blocks and tighten the radius of the curve. Break wings off by tapping on the back of the wing to obtain a clean break. For the AB Fieldstone anchoring units, use a hammer and chisel in the existing score line.

Building Tighter Curves

Using full size blocks in tight curves will create a gap between the courses. For cleaner lines, it may be necessary to remove parts of the bottom notch to fit the blocks closer together.

Capping Curves

Capping a curved retaining wall takes a bit of cutting and fitting, but produces a beautiful finish. Be sure to wear appropriate safety gear, including protective eye wear, dust mask, and hearing protection when cutting, and operate power saws carefully. See full details here.

• Place two caps on top of the retaining wall, spaced so a third cap will fit tightly between their widest point.
• Set another cap on top of the first two caps in the center and mark where they overlap on the bottom of the center cap.
• Remove the center cap and cut along the marks. Then set in place so the three fit tightly together.
• For complete details see instructions on building curved retaining walls.

Set Capstones

Measure and Cut

Place Capstones

• When building an AB Ashlar Blend or an AB Aztec Blend retaining wall, if an AB Junior Lite or AB Aztec Jr Lite is not available, the AB Lite Stones or AB Aztec Lite Stones can be cut to produce two (2) AB Half Lites. It is good practice to pre-cut the desired number of blocks ahead of time to speed up the installation process.
• Offset each new pattern from the pattern below to maintain the "random" appearance.
• Use a two (2) course pattern on retaining walls that have numerous inside and outside curves. This will speed up the installation process.
• Use the two (2) course pattern when building a patterned curve. It is easier to work with than the three (3) course pattern. Learn how to build curves with this easy step-by-step process. To build tighter inside or outside curves learn how here.

• Removing the “wings” of the blocks will be needed on projects with curves, corners or step downs on the AB Fieldstone Anchoring Units. For smooth outside curves, remove one or both of the “wings” from the back of the anchoring units and tighten the radius of the curve. Break wings off with a hammer and chisel in the existing score line to obtain a clean break.
• When working with corners and/or stepping down a wall, split an anchoring unit in half to tie the corner together. Split the block by using a hammer and chisel to make a break down the center of the block.
• On some projects you will need to modify the bottom lip of the block to fit on the course below. Use a hammer and chisel and tap along the lip to remove.