Retaining walls hold back soil when there is a difference in earth elevation. Many retaining walls in Rockville, MD are used to terrace yards with steep slopes, to help create usable outdoor space, and to control erosion. Low retaining walls are mostly used as planting beds and can add interest to an otherwise flat yard.
It’s important to have a basic understanding of what goes into proper retaining wall design before you hire someone to build a landscape retaining wall on your property. Here are four things to consider:
- Base: a retaining wall must be built on a suitable base, set below ground level. The taller a wall is, the further below ground level it should be set. In order to support the rest of the wall, a good base should consist of compacted soil and at least a six inch layer of compacted sand and gravel.
- Backfill: a retaining wall must have properly compacted backfill dirt behind the wall. There should be at least 12 inches of granular backfill (gravel or a similar aggregate) installed directly behind the wall in order to provide proper drainage. Compacted native soil can be used to backfill the rest of the space behind the wall. If you intend to do landscaping behind the wall, a 6+ inch layer of native soil should also be placed over the gravel fill.
- Drainage: efficient drainage is important, since water can’t pass through most retaining walls. Drainage problems can cause bulging or cracking in your retaining wall. How to ensure proper drainage of water from behind a retaining wall? You can require that your landscaping contractor backfills at least a foot of space behind the wall with gravel. You can also have a perforated pipe installed along the inside, or backfilled, bottom of the wall. Be sure to ask your landscaping contractor if weep holes will be needed to allow water to drain through the wall.
- Height: the height of a retaining wall determines the load it can bear and how much extra reinforcement will be necessary. Residential retaining walls are usually built between 3 and 4 feet high, because that height provides excellent strength without requiring additional reinforcements.
For more information on retaining walls in Rockville, MD, please contact East Coast Landscape Design, the Washington D.C. area’s leading licensed landscape design company. Located in Montgomery County, Maryland since 1979, the company, under the leadership of President Mark Simpson, has designed and installed landscape projects, including patios, outdoor kitchens, driveways, and retaining walls.