Seven Important Facts About Building Retaining Walls


Here in Northern California’s Bay area, retaining walls perform an essential function. Their strength and functionality allow contractors to build homes in the most unlikely places, like the side of a mountain! A retaining walls main purpose is to hold back soil when there is a change in the topography of a property. They’re used to terrace yards, control erosion, and create usable outdoor space.

While they’re primarily functional, they can also add a beautiful element to your outdoor landscaping. Low retaining walls can be used as planting beds and if you have a flat yard, can add an interesting visual element.

They may look like simple stacked stone, block or timber but retaining walls are carefully engineered systems that are designed to restrain tons of saturated soil that might otherwise slide away from a foundation or damage the surrounding landscape.

Here are seven essential facts to be aware of if you’re planning on building a new concrete block retaining wall.


The main cause for retaining wall failure is poor drainage resulting in saturated soil. That’s why an appropriately built retaining wall consists of 3 critical elements – landscape fabric, backfill, and 4” perforated drainpipe. Whether you’re building a retaining wall to address topographical changes on a piece of property, or as a functional decorative element of your hardscaping, proper construction is crucial.

Here are seven essential factors to consider when it comes to properly building retaining walls.

  1. Proper Base Preparation Placing your wall on a proper base is the most important factor for safe construction. Manufacturers, contractors, and engineers all stress the importance of starting with a solid base. The base of a concrete block retaining wall should be placed below grade. The depth of the base is dependent upon the height of the wall. The base is critical for supporting the rest of the wall. A proper base is constructed of compacted soil and at least a 6-inch layer of compacted sand and gravel.
  2. BackfillIn order to perform the function of holding back tons of soil, proper backfilling is necessary. Backfill refers to the dirt behind the physical wall. To provide proper drainage at least 12 inches of gravel or a similar aggregate should be installed behind the wall. If you’re planning on adding plantings behind the wall, use compacted native soil placed over the gravel backfill.
  3. Install Proper Drainage Most retaining walls are impervious to water meaning that water can not pass through the stone structure. Proper drainage is crucial to prevent structural failure. Improper drainage can cause hydrostatic pressure to build up behind the wall causing bulging or cracking. There are several ways to ensure proper drainage. Proper backfill behind the wall, installing a perforated drain pipe along the inside or backfilled bottom of the wall, and adding weep holes to allow water to drain through the wall can ensure structural integrity will be maintained.
  4. Height Considerations The height of your wall will determine its load bearing capacity and how much reinforcement is needed. Low walls between three and four feet high can provide excellent load bearing without the need for additional anchors, cantilevers or other reinforcement. If your property requires a taller wall, your landscape contractor will need to bring in an engineer to design an appropriate system or can terrace the landscape using a series of three or four foot high walls.
  5. Use A Waterproof Membrane To Prevent Efflorescence Moisture can stay behind your retaining wall long after the runoff is gone. It will permeate the masonry and evaporate on the dry side leaving behind a white powdery residue called efflorescence. This is a natural process. Use a waterproof membrane on the back of the wall to prevent this from happening. There are different types of membranes available, and your contractor will know which is appropriate for your situation.
  6. Retaining Walls are Functional… and Beautiful! Retaining walls are primarily functional elements of your landscaping, but that doesn’t mean that they can’t be aesthetically beautiful! Consider incorporating a water feature or outdoor fireplace into your design for a dramatic effect. For a finished look install wall caps and landscape lighting, or practical bench seating.
  7. Hire a Professional Concrete Block Retaining Wall Contractor For the best results working with a professional landscape contractor is recommended. They can help you to design and engineer your wall, will have the knowledge and expertise of local soil conditions and can provide high-quality materials and proper construction to ensure safety.

Retaining walls are functional elements of your landscape design that can also be a beautiful focal point of your outdoor living space. Proper planning and installation can ensure that your retaining walls will perform their job for many years and look great at the same time.

If you’re considering adding a retaining wall to your Sonoma County home, give the experts at Bayside Pavers a call at 1-(866) 287-2837. We can help you design and install the perfect retaining wall system to meet your property’s unique needs. Our knowledgeable team members are ready to help you create the outdoor living space you’ve been dreaming about!


If you’re in the San Francisco Bay area, our location in Concord, CA at 2455 Bates Ave, Ste K, services East Bay and South Bay homeowners. Our Santa Rosa, CA location at 1619 4th Street Ste 12 can help you with your North Bay hardscaping projects.

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