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4 Ways to Help Prevent Retaining Wall Failure

Thursday, January 20th, 2011

© Clint Pino, Cornerstone Retaining Walls, Inc.

Retaining walls are so much more than beautiful landscape elements.  They are workhorses built to restrain the earth behind them.  They need to hold up under constant pressure as the force of gravity pushes against them, or else they will fail.  Failed walls will sag, crack, bulge, lean, produce large gaps, or collapse.  Often times, the only way to fix a failed retaining wall is to tear it out and rebuild it.

The good news is that most retaining wall failures can be avoided.   Let’s take a look at 4 preventive measures you can take to help ensure your retaining wall will hold up.

1.  Drainage. The lack of proper drainage is the most common reason for retaining wall failure.  When water is absorbed into the soil behind a retaining wall and it has no place to go, the pressure behind the wall is increased.  If the water continues to build up, it will eventually push the wall out, causing it to bulge or collapse.  Installing drain pipes and using a clean, granular rock for both the backfill and the base of the wall will allow water to drain out.   The pressure will be released and wall failure will be prevented.

2.  Compaction. Poor compaction will eventually cause a retaining wall to shift, producing large gaps within the wall.   The soil needs to be compacted once at the point of excavation, again after the gravel base has been added, and each time backfill is added.  (Backfill should be added after each course of the wall has been installed).  The most effective way to do this is to use a piece of machinery called (you guessed it!) a compactor.

3.  Reinforcements. The type of reinforcements needed depends on a number of factors – the soil conditions, the type of material being used to build the wall, and the height of the wall.  The most common type of reinforcement for modular block retaining walls and rock retaining walls is geogrid.  Geogrid is a mesh-like fabric that helps stabilize the soil and secure the wall.  It is normally added every 2 or 3 courses.

A wall built in clay-like soil will need more geogrid than a wall built with sandy soil.  Likewise, a tall wall will need geogrid for extra reinforcement, whereas a short wall normally will not.  Timber retaining walls require deadmen, which are timber secured perpendicular to the wall.  Deadmen help anchor the wall to the soil it is supporting, increasing stability.

4.  Engineering. Certain conditions call for a retaining wall to be professionally engineered before it can be built.  Walls exceeding a certain height (usually 3 – 4 feet, depending on soil conditions) should always be engineered.   Retaining walls that will need to hold up against additional pressure, such as a wall restraining a parking lot, should be engineered.  Local city or county ordinances may also require engineering for retaining walls.

Before You Get Started

Before you get started, do your homework.  If you are hiring a builder, talk to them about retaining wall failure.  Review your contract carefully to make sure all the costs needed to build the wall properly are included.  If you are going to do it yourself, be sure to follow the installation instructions.  Check into local ordinances for retaining wall requirements.  Don’t hesitate to consult with your supplier or a professional retaining wall builder if you need assistance.

When built properly, retaining walls have the potential to last hundreds of years.  Investing in the proper materials and taking the time to build it right will mean all the difference between a retaining wall that lasts and a retaining wall that fails.

Cornerstone Retaining Walls, Inc. is committed to building retaining walls that will last a lifetime.  To view pictures of projects or to get more information, log on to www. or call Clint at 303-564-4175.

Retaining Walls…an Easy, Affordable Way to Spruce Up any Landscape Design

Monday, June 22nd, 2009

Retaining Walls…an Easy, Affordable Way to Spruce Up any Landscape Design

Retaining walls are beautiful structures that can seamlessly be worked into any landscape project. They can add visual interest to the landscape, serve as planters, add usable space to a yard, frame a patio or courtyard, or add a backdrop to other landscape elements.

There’s simply no denying the stunning visual effect that retaining walls have on a landscape design. They add lines, textures, colors and patterns that work harmoniously with other landscape elements in addition to complimenting the natural surroundings. Retaining walls can transform a yard into an old world style courtyard, give it the feel of a Spanish-style villa or an elegant oasis.

There’s a reason that the majority of homebuilders are big proponents of utilizing retaining walls. Retaining walls help to stabilize the slope, support the foundation of the house and reduce runoff. They cut back on the amount of fill needed and reduce disturbance to the natural vegetation. In addition, retaining walls enhance the beauty of a home and add value to it.

The Benefits of Modular Block Retaining Walls

Modular block is the preferred material for landscape retaining walls because it holds up beautifully in a harsh climate, such as we have here in Colorado. Modular block will not rot or decay, nor will it release harmful chemicals into the ground. The result is a retaining wall that not only looks good, but is environmentally friendly and will last a lifetime.

Modular block comes in an exciting variety of shapes, sizes, colors, textures and styles. Two popular styles are tumbled block and the Ashler pattern. Tumbled block has a weathered, antique feel and portrays the look of natural stone. The Ashler pattern is multi-dimensional, that is, it utilizes blocks of different shapes and sizes to create the effect of hand-laid stone. Tumbled block and the Ashler pattern can be combined to create a myriad of different effects. Both come in solid or marbled colors.

Retaining Wall Considerations

Things to consider when installing a retaining wall are base, backfill, drainage, compaction, stabilization and reinforcement. Clean, crushed rock should be used as the base of the wall to provide a firm foundation. It should also be used inside the block and behind the wall to provide proper drainage. Some walls will need to utilize geogrid for added reinforcement and stabilization. A compactor is needed to properly compact the backfill and soil to prevent the retaining wall from moving or shifting.

Whether you have an existing home or are building a new home, whether you live in the city, on the plains, or in the mountains, whether your property is flat, gently sloping or has a steep grade, a retaining wall will add beauty, value, and intrigue to your outdoor environment.

Cornerstone Retaining Walls, Inc. is located in Evergreen, CO and specializes in the installation of modular block.  To view pictures of projects or to get more information, log on to www. or call Clint at 303-564-4175.