Lighting Segmental Retaining Walls

By Allison Uher

The lights in the foreground are partially covered with a protruding shade that aims the light in a chosen direction such as steps. Lights in the background are self-contained units casting more light on a general area.

As segmental retaining walls become increasingly popular components in a landscape contractor’s “toolbox.” Demand for product innovation is heightening similarly. Clearly, modular concrete retaining wall systems have proven to be a more cost-effective and longer-lasting alternative to their most commonly used counterparts–cast in place concrete and pressure-treated timber walls–but the drive towards further advancement hasn’t slowed down. Landscape contractors and clients want products that are functionally and aesthetically elegant. Retaining walls are expected to blend in with the native environment. Simply put, SRWs must get the job done and look good doing it.

A tall order perhaps, but manufacturers are eager to step up to make their products even more capable of multi-tasking. One way to do so is with lighting. As any good designer knows, lighting is a crucial means of making a space usable and beautiful. Effective lighting can be employed to draw attention to eye-catching landscape features and illuminate obstructions that are potentially hazardous. A relative newcomer to the lighting scene is the category of retaining wall lights. A variety of options exist, but all aim to enhance the appearance of the walls in which they reside, while increasing the level of safety for pedestrians.

It is difficult to tell the difference between the lighting units and the concrete blocks during the daylight hours.

One popular choice for retaining wall lighting is the method of attaching a fixture to an existing block. A possible variant of this technique involves insetting the fixture so that it is flush with the face of the wall. The installer must first measure and drill out the hole to the proper width/diameter and depth, and then secure the fixture to its power source (with the wiring presumably leading through the rear of the block). This process requires exact cutting and placement, making it less suitable for do-it-yourself landscapers. A less complicated manner of attaching a lamp to an existing retaining wall block is to simply fasten it to the face. Some drilling and cutting will be required, but since the attachment is not expected to be flush with the wall, precision is not as vital an issue. These lights are often partially covered with a protruding shade that aims the light in a chosen direction.

Some retaining wall manufacturers have opted to create lights that can be built into the wall in the same way as the rest of the structural units. Risi Stone Systems produces RisiLights??????oe with are self-contained, fiberglass and acrylic units that have been textured and color-matched to resemble their adjacent blocks when installed. Pisa2??????oe retaining walls can easily handle grade changes in landscape or garden projects and can be used to increase the amount of usable space for patios, terraces and parking. These units are manufactured in pairs, face to face. The rough surface is achieved by splitting the units apart using a simple hammer and chisel. PisaStone??????oe is best for the construction of retaining walls with straight segments and angled corners or stairs. The units are manufactured in pairs with a splitting groove between them. This allows the units to be easily broken apart on site with a hammer and chisel to produce a clean-cut stone finish.

Color and texture matching allows walls to meld with the surroundings.

This segmental retaining wall system is composed of standard units in three depths, a coping unit, and a corner unit. Corner units provide a lap joint arrangement for inside and outside corners.

With the lights switched off during daytime hours, it is difficult to tell the difference between the lighting units and the concrete wall blocks for both systems. This seamless color and texture matching affords the walls the capability to truly blend in unobtrusively with their surroundings. The lights are shipped complete with instructions and wiring; the only additional items needed are the light bulb and the appropriate underground electrical cable.

The lights are used to illuminate walkways, steps and terraces. They are installed using a conventional 110-volt power supply. If you prefer, a 12-volt power supply may be used, but the light socket provided will need to be replaced with an appropriate low-voltage light socket.

A timer or photoelectric control unit may be used with the lights, but should be installed at the power source. This allows all of the units in that circuit to be centrally controlled. Multiple light units may be connected in a parallel circuit with a second external wire continuing to the next light through the second opening in the rear of the unit.

Retaining wall lights can illuminate walkways, steps and terraces. A standard low voltage transformer or photoelectric control unit may be used with the lights, but should be installed at the power source.

No matter which sort of retaining wall light you choose, planning must be done from the initial stages of design to ensure proper placement. Utilities must be located, underground cables positioned, and the situation of lit areas such as walkways, stairwells, and passages must be determined. Any number of variables may need to be addressed during the design phase of the project. For example, if the design calls for stair treads to be illuminated via fixtures on the risers, high-strength lights that can withstand foot-traffic surcharges must be specified. With careful planning, retaining wall lighting can be an effective way to create a safe environment and accent the landscape design.

Now that you know what must be done to install the lights into the retaining wall, here is an overview of a program to help you build a safe and secure structure. For a designer to do a complete design of a gravity retaining wall or a geogrid reinforced retaining wall, they will spend great deal of time doing repetitive calculations. Once the design is determined, they must generate several detailed construction documents to ensure what they have designed is accurately communicated to the persons building the wall.

RisiWall??????oe eliminates most of the tedious calculation and documentation necessary in the design. The program can operate as an analysis tool and check a design created by the user, or it can function as a design tool and determine the reinforcement necessary to create a stable wall. This obviously makes the program and the design of the wall an interactive process. The program guides the user through the design in an orderly step-by-step manner. The designer is required to make decisions about their design throughout the entire process. This allows the user to review the profile design, panel layout, cross section parameters, geogrid placement (if required) and the calculated factors of safety. The designer participates in the design of every panel, but the program will do all the time-consuming calculations. When a wall designs fails to meet the required standards, the program provides hints and several options that can bring the wall up to the required standards.

When the program is used as an analysis tool it will identify user designs that will not meet the required standards and may not even be stable. At least the program will save you time and money before you start to build.