The safest, best way to avoid any cracking in your retaining wall is to take matters into your hand from the very beginning and to plan it and build it so, that cracks have minimal chance to appear.
Interlocking block retaining walls are understandably becoming popular in San Diego, as not only they blend into the going green movement, but it is also easy to forget about cracking with retaining walls of this type.
Once you have decided to reshape your backyard and give that steep slope a fresh new looks by terracing it, you might want to learn more about interlocking block retaining walls. These walls are built from interlocking blocks that connect with each other through a lip on the front or rear side that locks into the block underneath, or through pins or dowels. Whichever technique used, the retaining wall strengthens once it is completely finished, because the soil pressure behind it helps the connection between blocks tighten even more. Once the wall is lined at the back side with landscaping fabric that does not allow soil and dirt to leak through the blocks, there is virtually no chance for cracks to appear. Materials for interlocking blocks include:
This type of retaining wall is best suited for lower walls. Low interlocking block retaining walls are easy to build in a DIY project. To assure strength and stability for a high wall for your slope, check¬† and adhere to San Diego building codes, especially where reinforcement, trenching and drainage is required.
Cracks appear due to shallow design and engineering, where lateral soil pressure, load bearing-capacity, groundwater conditions and soil properties are not all carefully taken into account. The retaining wall must be able to resist lateral soil pressure and to also have the strength to push back. Poor compaction and improper drainage adds to soil pressure and significantly weakens the retaining wall, causing blocks to crack, distort and even break. Safe engineering is the key to strong and stable structures and retaining walls are in no way exception from this. Note that to build a retaining wall higher than 3 feet in San Diego you need to obtain the city permit.