The key to building a low-cost retaining wall is finding inexpensive but durable materials. Although not as long-lasting as stone or concrete versions, wooden retaining walls often cut the cost of construction significantly. Using landscape timbers or railroad ties instead of buying lumber can cut costs even more if found or salvaged independently. After leveling the ground, install a footing plate, and then attach the wall frame. Add struts and sleeper beams for support, and panel and finish the wall.
The footing plate, frame, struts and sleeper beams can be constructed from the landscape timbers or railroad ties. Dig a trench in the desired location. Lay the wooden footing plate in this trench, and then stabilize it by packing it with gravel. Gravel is an inexpensive but a sturdy and reliable alternative to concrete for anchoring the retaining wall.
Build the frame by creating square sections and fastening them with screws or galvanized nails. These sections should chain together to run the desired length of the wall. Screw down the base of the frame to the footing plate. Use lumber to panel the wall frame, making sure to leave a hole to install the struts. Install the struts into the wall panel. Install the struts into these holes, and fasten them with screws. Secure the supportive sleeper beams to the struts.
Finish the wall by adding trim board to the paneling. The trim board and paneling should be moisture-sealed to prevent damage to the wood. The trim board can be made from the same landscape timbers or railroad ties. Dry-stack rocks can also be stacked in front of the paneling to create an aesthetic trim board. Using rocks from around the landscape is another inexpensive yet decorative option.