Photos: Courtesy of Unilock®

Base Thickness Chart

Soil condition - In areas with poor soil conditions, (eg., heavy clay, disturbed soils) increase the depth of the base to provide more stability. Where
poor soil conditions exist it may be advisable to contract an engineer when constructing a retaining wall in excess of 24” in height.

Basic Installation

Tools required

• Wheel Barrow
• Rake
• Level
• String
• Tape Measure
• 3 lb. Mallet
• 3" Masonry Chisel
• Masonry Saw
• Shovel
• Hand Compactor
  (For jobs over 75 sq. ft. rent a gas powered compactor)
• Gloves
• Safety Glasses

Whether you're installing yourself, or hiring a Unilock Authorized Contractor, there are some basic procedures that we have outlined below that will help ensure a solid and attractive installation, an installation that will show your pride of ownership and increase the value of your home.

Step 1: Planning

Draw a plan view showing measurements and grade elevations. The elevations are required to calculate how many retaining wall blocks are required.

Step 2: Preparation

Mark out the location of the wall. Before digging, call local utilities and cable to mark locations (this is usually a free service).

Step 3: Excavation

Excavate a minimum of 6" - 12" deep depending on the size of wall unit you are using. Excavate more if the soil has been previously disturbed. Remove all loose soil. Remember that you need a minimum of 3" of gravel base and at least 3" of wall unit buried below grade level to help "toe in" the wall. You can save on materials if you step the wall up or down to accommodate the grade.

Step 4: Base

Place 3" - 6" of gravel (see Base Thickness Chart) in the trench and compact using a hand tamper. (See top left photo). Compact until very hard. In areas with more than 6" of gravel, compact in 3" layers. Leave enough room for the first row of wall units to be buried below grade level. The final height of your installation will determine the exact level you must set your base at.

Step 5: Screeding

Some wall styles come as "doubles". Split them first. Level the blocks individually using a mallet and a small level. Ensure that all blocks are leveled from side-to-side and front-to-back. After the first row is in, the rest of the units can be stacked. Off-set all vertical joints by starting with a block cut in half.

Step 6: Laying the Pavers

Add gravel backfill after every 2 rows of blocks. Use well draining gravel. See cross sections for quantities required behind the wall. Always use a filter fabric to separate the existing soils from your gravel. Leave enough filter fabric to wrap the top as shown in the cross-section details.

Step 7: Cutting

When placing your final row of blocks, (in some cases this might be a special cap called "coping"), you must glue them on with Concrete Adhesive. Always dry-fit and cut any pieces required before gluing. After gluing, place in soil, put in sod, or install plants to complete your installation.