Rock and Block Retaining Walls for Landscaping
Green Sustainable Building Material or Decorative Concrete Blocks
May 15, 2009
But aren't they just rocks? Why should rocks be expensive? For two reasons, basically. Rocks that lend themselves to long lives, like granite, are in high demand for granite countertops, driving up price. It's the old supply and demand market rule.
Secondly, rock is very heavy. If the home is not in an area that naturally has an abundance of usable rocks for this green landscaping project, transportation is very expensive. This is not such an issue with concrete blocks.
An Attractive Raised Bed Garden
Regardless of which building material is used, this is a very attractive way to build a raised bed vegetable garden or a flower bed. With enough real estate, terraced gardens may be constructed. Where the homeowners insurance policy covers this home improvement, it should be updated.
The Concrete Block Retaining Wall Alternative
Preformed concrete blocks are a viable alternative to natural stone. The look is not as rustic but the materials are more affordable and the construction is less labor-intensive.
Since the blocks have interlocking lips, no mortar is required for assembly. Since these blocks are not put together with mortar, they should be used for walls that are no higher than 3 to 4 feet high.
Installing the Block Wall
- Determine where the wall will begin and where it will end.
- Use a flat-tipped shovel to dig a foundation trench about 2 inches deeper than the height of the block and tamp the soil down.
- Add 1 inch of leveling sand to the bottom of the trench.
- Lay the foundation course in the trench.
- The block's joints on alternating courses should be staggered. This strengthens the wall. Blocks are easy to half using a brick chisel and a 3-pound sledge hammer.
- The back side of the wall can be lined with landscaping fabric before filling it with dirt.
Procedure for Building the Wall with Stone
Natural stone offers more than one challenge that decorative concrete block does not. One of the biggest to contend with is the fact that each piece is uniquely shaped. This means that care must be taken when selecting adjacent rocks.
Rock walls can either be mortared or dry-fit. In either case, it the completed project is to be over 3 feet high, the job should be done by a professional.
Dig a trench as in step 2 above. The foundation course should be buried at least 90 percent.
Use the largest flat-sided stones at the bottom, using increasingly smaller rocks on the higher-up courses. Save flat heavy stones for the top course or capstones. This will strengthen the wall.
Decorating the Wall
Natural stone structures really look good with native plants in the gaps and cavities. Choose species that are hardy and virtually maintenance free.
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