Building Curves

Curved and serpentine walls are simple to build. Allan Block’s patented design allows for easy installation of both inside and outside curves. Most curves can be built with no cutting involved.

• Try to maintain an offset of the vertical seams by at least 1/4 of the block length from the courses below for both inside and outside curves. Cutting a block in half or using the half width blocks - AB Jumbo Jr. from the AB Collection, AB Aztec Jr. from the AB Aztec Collection or AB Palermo from the AB Europa Collection, will assist in creating a proper offset.
• Before constructing your wall, layout the design using a garden hose or paint. Measure the radius of each curve and refer to the radius chart below. Select blocks that will fit your design or adjust your design to fit the blocks you have selected. As a rule, gentle sweeping curves produce more aesthetically pleasing walls.

Video: How to Build Inside Curved Retaining Walls

Video: How to Build Outside Curved Retaining Walls

Inside Curves

• To build a flowing inside curve, keep the front of the blocks tight together and fan out the blocks keeping the space 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. To obtain a clean break, hit the back of the wings with a hammer or for the AB Fieldstone anchoring units, use a hammer and chisel in the existing score line.

Determining the Radius

Curved walls have a greater setback, which causes a coning effect to occur causing your retaining wall to have its tightest radius at the top of the wall which in turn creates the need for a larger radius at the base course.

The final height of the wall will determine what the minimum radius at the base course must be. Use the radius chart to determine what the minimum recommended radius of the base course of the wall needs to be, so the top course of the wall will not be less than 4 ft. (1.2 m).

Depending on the block you choose, the tightest radius at the top of the retaining wall is:

• AB, AB Aztec, AB Metropolitan or AB Europa Collection
  • Full size block is 4 ft. (1.2 m), half width block is 2.5 ft. (0.8 m).
• AB Fieldstone Collection
  • The 812 assembly with a short anchoring unit is 5.25 ft. (1.6 m).

Starting the Curve

From the point of where the curve will start, measure straight back from the wall the required amount (shown in the radius chart) and drive a stake into the ground. This will be the center of the curve. Attach a string line to the stake the length of the radius and rotate it around to mark the location of the base course. Install the blocks with the front of the blocks lining up with the mark.

• To transition the curve back into a straight wall or another curve, lay out the curve and the first couple blocks of the next section. Adjusting 1 or 2 of the blocks will help in the transition of the next section of the retaining wall.

Building Tighter Curves with Allan Block Collections

• The easiest option is to use half width block - AB Jumbo Junior, AB Aztec Junior or the AB Palermo whenever possible to build tighter curves within the wall
• When using full size blocks, it may be necessary to remove parts of the bottom notch to fit the blocks closer together.