Many concrete retaining wall stones stack and lock atop each other, such as the stones in our project. Often prestained or textured, they quickly create sturdy, natural-looking walls. Always start with a solid, level base. Walls less than 3 feet high can be installed without mortar, cement mixing, reinforcement such as rebar, or special tools. Walls any higher require professional expertise to avoid a very dangerous potential for collapse.
Here are some other ideas for this building technique.
Problem: The area beneath a tree is shaded and a difficult place to grow a lawn. Solution: Build a retaining wall two blocks high around the tree's drip line. Fill with soil (don't mound it against the tree trunk) and plant shade-tolerant annuals and perennials or a shade-loving groundcover.
Problem: Drainage and soil are poor, but you'd like to grow vegetables. Solution: Build raised beds and fill with composted manure and soil. A sunny raised bed will ensure proper drainage, and the stones absorb and hold heat so the soil will warm earlier in the spring.
Problem: The uneven areas around your hot tub or deck steps are hard to plant. Solution: Build terraces into the sloping area and alongside the steps.
1. Plan the wall. This driveway runs along a slope, which is difficult to plant and erodes after rainstorms. A retaining wall will control water runoff and make the house's entrance more attractive. Use a hose to outline the wall position.
2. Dig a trench at the base of the slope. Make the trench 1/2 inch deep for every course of block and no less than 2 inches deep.
3. Add rock. Spread several inches of crushed rock into the trench and compact it using a 4x4 or a plate compactor. Once the base is compacted, begin installing the base course.
4. Prep the stones. This stone has a locking lip. For the base course, knock the lip off with the back of a hammer, or just press the stone into the ground with the lip intact.
5. Set the first course. Make sure it is level. For curves, leave a slight space between the units. Backfill after each course is completed.
6. Offset the stones when stacking. This ensures the integrity and strength of the wall. The interlocking design of the stones also adds strength.
7. Add courses. We built our wall to stairstep from ground level to 3 feet high. If your stones do not interlock, periodically set a double-length stone crosswise to tie into the hillside for extra support.
8. Landscape. The finished wall frames the landscaped hillside, which will fill in. An accent lantern adds interest. If you construct the wall back several feet from the driveway, you may have room for plantings along the wall's base.