Walls intended to hold earth in place are tricky constructions requiring careful design, but they are much simpler to build these days than in the past.
Retaining walls are used to beautify landscapes as well as prevent soil erosion, and they help make sloping or hilly land usable.
Helping to simplify construction of the walls are modular concrete-block systems that require no mortar and generally have built-in alignment systems.
Mortarless blocks are available in a variety of sizes and designs and colors, and can produce retaining walls of symmetry and beauty. Most blocks have a rough face resembling chiseled stone or granite.
"Mortarless blocks are really taking off," said A. Shafer Henry, vice president of E. P. Henry Corp. of Woodbury, N.J., manufacturer of block systems called StoneWall and StoneRidge. "We did one retaining wall last year that is 31 feet high."
StoneWall features blocks weighing about 65 pounds each and measuring 16 inches long, 8 inches high and 12 inches deep. Courses of blocks are held together with aluminum clips that help align the blocks so that each new course is set back 3/4 -inch from the course under it. The setback produces a wall that tilts slightly against the weight of the earth behind it, adding strength.
E. P. Henry blocks are sold through a network of dealers in New Jersey, Pennsylvania, Delaware and other states. For more information, call (800) 444-3679.
National and regional manufacturers make it possible to buy mortarless blocks of various types almost anywhere in the United States. One of the most widely sold brands is Keystone blocks, available at some masonry-supply dealers and home centers. These 18-inch-wide blocks are held together and automatically aligned with fiberglass pins.
From a do-it-yourself standpoint, one problem with full-size blocks such as StoneWall and Keystone is their weight -- up to 90 pounds each for some blocks -- which makes them difficult to TTC handle, so some companies have designed smaller mortarless blocks for small walls.
For example, E. P. Henry recently introduced StoneRidge, a 30-pound version of StoneWall. StoneRidge blocks are 12 inches long, 6 inches high and 8 inches deep, and, according to Mr. Henry, can be used for walls up to 30 inches high.
A relatively lightweight mortarless block called Garden Wall, for walls up to 24 inches high, also is available from some dealers. Garden Wall blocks are solid concrete but weigh only about 23 pounds each.
Readers' questions should be sent to Gene Austin, c/o The Baltimore Sun, Box 8263, Philadelphia, Pa. 19101.