Retaining walls are seemingly simple structures that hide a surprising amount of complexity and engineering know-how. You can find these walls nearly everywhere, from major commercial developments right down to residential hardscapes. While retaining walls can beautify an area, their primary purpose is to hold material in place and resist gravity and erosion.

If you're planning on installing a retaining wall in your yard, you might be surprised to learn that there's more to these structures than meets the eye. While there are many types of retaining walls with varying functional and aesthetic purposes, they all include these critical structural elements.

1. Stem

The retaining wall's stem is typically the most visible element of the structure. If you're unfamiliar with the engineering involved in more substantial retaining walls, the "stem" may seem synonymous with the wall itself. A standard retaining wall stem is either vertical or near-vertical, although many residential retaining walls use a step-back design that "leans" against the ground they're holding back.

The stem must resist the force of the soil pressing against it without leaning or failing. The more soil you're trying to hold back with your retaining wall, the more support your stem will need. Tall or long retaining walls may require a significant amount of design and engineering work to ensure the stem portion can serve its function over the long term.

2. Drainage

Drainage is critical for all retaining walls, even relatively small, decorative walls used in hardscaping. The soil behind the retaining wall will naturally collect moisture from rain, increasing the amount of hydrostatic pressure on the stem. Without drainage to release this pressure, the wall will inevitably fail over time.

Numerous options exist for drainage, depending on the size and design of the wall. Many retaining wall blocks include gaps for drainage, but more substantial walls may require more complex systems. For instance, some concrete walls may use buried to direct water around and away from the wall, similar to a French drain system around a house's foundation.

3. Footing or Foundation

Like any other structure, retaining walls require a solid foundation. While small walls may require only a simple gravel base course, larger walls often need purpose-built footings or concrete slabs. Cantilever-style walls include both a toe and heel slab to help resist the forces on the wall and keep the entire structure from shifting due to the weight of the soil.

Since even a seemingly simple retaining wall may require numerous structural design decisions, it's often best to work with an experienced landscaping contractor to build one. A professional can help advise you on the best wall for your needs and construct a wall that will stand up to time and changing environmental conditions.

For more information, contact a local company, like Rosebrooke Land and Home, LLC.