Soil placed in front of and behind base course units. Also soil placed behind drainage aggregate. All backfill should be well compacted. Loose backfill will add pressure on walls, collect water, cause settlement and will not anchor soil reinforcement materials properly. Backfill that is behind a wall containing soil reinforcement is often referred to as reinforced soil.

Base Course

The base course is the first layer of VERSA-LOK units placed on the leveling pad. Extra care should be taken to ensure that all base course units are level front to back, side to side, and with adjacent units. Unevenness in the base course becomes magnified throughout succeeding courses and cannot be easily corrected.


The arrangement or pattern of units from course to course. A unit that is centered over the joint created by the adjacent lowercourse units is placed on "1/2 bond." VERSA-LOK's unique pinning system permits variable-bond construction and allows units to fit close to each other while interlocking correctly. In general, VERSA-LOK units should be installed on 1/4 to 3/4 bond — where units overlap vertical joints of adjacent lower course units by at least four inches.



Applying mechanical force to soils so they are no longer compressible. It is important to compact foundation and backfill soils to prevent future wall movement. Compaction is often accomplished using a hand tamper or a vibratory-plate compactor (available at most rental stores).


A horizontal layer of retaining wall units.


Drain Aggregate

Clear, free-draining, angular gravel placed directly behind retaining wall units to expedite drainage. Drainage aggregate should not contain fine particles that could impede water flow.

Drain Pipe

Typically, a four-inch perforated pipe placed behind the wall at the base of the drainage aggregate. The drain pipe helps to direct large amounts of water from behind the wall to areas where it can accumulate safely away from the wall.



VERSA-LOK segmental retaining walls should have at least one-tenth of exposed wall height embedded below grade. For example, a four foot wall should have approximately five inches of the base course buried below grade. Embedment provides enhanced wall stability and long-term protection for leveling pads. Embedment should be increased for special conditions such as slope at wall base, soft foundation soils, and shoreline applications.



The ground level, or ground elevation.

Gravity Wall

A retaining wall without soil reinforcement where unit weight alone provides resistance to earth pressures. Gravity walls are generally less than four feet in height and do not support slopes or other loads above the walls.


Impervious Fill

Backfill placed above and below the drainage aggregate. Impervious fill helps to prevent large amounts of water from running down behind the wall or getting to the leveling pad. Generally, compacted fine grained soil is used as impervious fill.


Leveling Pad

The base on which a wall is constructed. Leveling pads consist of well-compacted crushed stone, gravel, or coarse sand. The most commonly used material for leveling pads is that which is used locally as road base aggregate.


Weight or pressure placed on a retaining wall — usually from the back or top. Nearby slopes, driveways, buildings, and tiered walls all represent potential loads on retaining walls. Designs for retaining walls that support loads should be reviewed by a qualified, licensed professional engineer.



Segmental Retaining Walls (SRWs) are dry-stacked, mortarless walls made of 100 pecent, low-absorption, high-strength concrete blocks, or units.

Saw Cuts

Saw cuts are made to modify VERSA-LOK units when smaller pieces are needed. Saw cutting creates a smooth, straight surface to meet cleanly with an adjacent unit. Saw cuts are generally made using a gas-powered cut-off saw equipped with a diamond blade -- available at most rental stores.


The distance that each course is aligned behind the preceding (lower) course. Each course is set back 3/4 inch from the front of the course beneath it. This arrangement causes walls to cant back into retained soil. Canted walls are structurally more stable than vertical walls because gravitational forces "pull" walls into retained soil.

Soil Reinforcement

High-strength, polymer geosynthetic material, such as fabric or geogrid, that is buried in horizontal layers behind soil-reinforced retaining walls.

Soil-Reinforced Wall

A retaining wall that incorporates horizontal layers of soil reinforcement material behind the wall. Soil reinforcement combines with soil to create structures that are strong and massive enough to support large loads. Soil-reinforced walls generally require a design by a qualified, licensed professional engineer (P.E.).


Splits are made to modify VERSA-LOK units — most commonly to create corner units. Splitting creates attractive, textured surfaces identical in appearance to front faces of units. VERSA-LOK units can be easily split using a hammer and masonry chisel or mechanical splitter. This capability allows the user to create a wide variety of corners.


The attractive, textured design on the front of non-weathered VERSA-LOK units. VERSA-LOK units are manufactured in pairs connected at their faces. They are then split apart, creating this appearance.


Tiered Walls

Two or more stacked walls with each upper wall set back from the underlying wall. Tiered walls can be attractive alternatives to single tall walls and can provide areas for plantings. To prevent an upper wall from placing a load on a lower wall, the upper wall must be built behind the lower wall a distance of at least twice the height of the lower wall. Tiered wall designs should be reviewed by a qualified, licensed professional engineer.


VERSA-LOK Adhesive

VERSA-LOK Adhesive is specially formulated to bond VERSA-LOK Cap Units to the top of walls. This adhesive remains flexible to accommodate the minor wall movement that may occur during freeze/thaw cycles.


VERSA-LOK cap units are used to attractively finish the top of VERSA-LOK retaining walls. Cap units come in two styles: A caps and B caps. Both cap styles are 14 inches wide at the front, but A caps taper to 12 inches wide at the rear and B caps increase in width to 16 inches at the rear. To cap straight walls, alternate A caps and B caps. Use A caps to finish walls with outside curves and B caps to finish walls with inside curves. Front faces of cap units may be placed flush, set back, or slightly overhanging (recommended) the face of the uppermost course of VERSA-LOK Standard units.

VERSA-LOK Retaining Wall Units

Premium retaining wall units offering easy installation, unmatched design flexibility and unsurpassed durability. Units are installed without mortar or concrete footings. An unlimited variety of curves, corners, and steps can be constructed using only standard units. These environmentally safe, solid concrete units provide a lifetime of virtually maintenance free performance.

VERSA-LOK Weathered Retaining Wall Systems

VERSA-LOK Weathered units have rough, worn, rounded corners and their faces are jagged and rocky. Of course, VERSA-LOK Weathered units possess the same solid, pinned characteristics as all other VERSA-LOK Retaining Wall Systems.


The VERSA-Lifter speeds installation of VERSA-LOK retaining walls by making it easier to lift and place units — especially on the base course. The two prongs of the lifter are inserted into pin holes in the VERSA-LOK unit. The action of lifting the handle secures the lifter to the unit and makes for easy, balanced lifting and placement.


VERSA-TUFF nylon/fiberglass pins are used to interconnect VERSA-LOK retaining wall units and help provide consistent alignment. Pins are non-corrosive and will not rust or stain wall faces.