Friday, February 25, 2011

Retaining Walls

Retaining walls serve to retain the lateral pressure of soil. Basement walls, for example, are retaining walls, but the term is most commonly used to describe the decorative or structural build-up of material to hold back soil on a sloped surface.  Most commonly, these are seen on shore lines of creeks, or on hilly slopes.  
As a landscape feature, retaining walls provide an eye catching focal point in a yard layout.  They must be designed to resist the pressure of soil, but also often are required to resist hydraulic pressure. Because these pressures are the least at the top of the wall, most designs allow for a tapered construction, thicker at the base than at the top.
Gravity walls are constructed in such a manner that they rely on their mass to hold back the soil, while cantilevered walls often have a footing that helps to distribute lateral pressure into vertical pressure on the ground below.  They generally are reinforced internally with steel.  Anchored walls are more commonly used in rocky terrain, with the wall anchored into the solid rock behind the wall.
For the typical homeowner, though, most retaining walls are designed with both practical and aesthetic uses in mind.  While a piled wall, consisting of precast heets of concrete, slabs of steel or thick timbers pounded into the ground may serve the practical purpose well, they may be quite unsightly.  Sometimes such designs are augmented by dry-stacking stone or brick in front of the sheet, to provide the illusion of a retaining wall constructed solely of that decorative material.
The most common landscaped decorative retaining wall is the cantilevered structure, using poured concrete, decorative imitation stone, or real rock and bricks.  These allow for a continuation of the lawn or garden surface right to the lip of the wall, without unattractive gaps.
A design option that is gaining in popularity is the use of interlocking bricks, that work much like a Leggo block system.  These bricks come in a plethora of styles, sizes, shapes and colours, and are easily installed by most dedicated handymen, in one or two days.
When installing a retaining wall that will also act to resist hydraulic pressure, it is important to install proper drainage systems, as well.  This is where the home handyman most often fails, and where consulting with a professional fence installer or landscaper becomes critical.
Professional installers also are able to provide the guidance that will turn a functional retaining wall into a work of art, deserving of attention and praise.  While the cost may be substantial, the benefits, in the log term, will readily exceed the investment.

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