When building a concrete retaining wall, starting with a solid, level and well-compacted base is an absolute necessity. Failure to do this will result in a weak, wavy wall. Bear in mind:
- If your wall is higher than four feet, most concrete block manufacturers require extra engineering and installation steps. These steps range from using special reinforcement fabric to installing a series of terraces rather than one tall wall. Most manufacturers provide good printed installation guidelines. If you purchase your blocks from a specialty landscape center, there may be an on-site designer or engineer to help you.
- Contact local utility companies to mark the location of underground wires and pipes. Telephone and cable television wires are often buried just beneath the surface.
- In the Midwest, the compactable base material is often referred to as “Class V” (as in the Roman numeral for five). In other regions, the rock may vary and the material may go by a different name. The important quality of the material is its different-sized rock and sand particles that interlock and compact to create a solid base. It’s the same material used beneath roadbeds and paver patios. Make sure you use the right stuff. It’s NOT the same as the crushed gravel you use for backfill.
- The 16-inch wide x 12-inch deep x 6-inch high blocks weigh 80 pounds each. A brick tong doesn’t make them lighter, but it does make them less clumsy to handle, easier to position, and less likely to crush fingers.
The Reader’s Digest Association, Inc./GID
Start off your retaining wall with a solid, well-compacted and level base.
