Why Retaining Walls Fail

Written by jessica kolifrath | 13/05/2017
Why Retaining Walls Fail
Retaining walls are often built along roads. (Photos.com/Photos.com/Getty Images)

Retaining walls support and retain the soil of a slope that would otherwise slide and ruin a garden or damage your home when saturated with rain. A retaining wall must be built correctly and from the right materials or it won't hold up to the pressure of heavy, wet soil.

Lack of Deadmen

Deadmen are vertical supports that provide extra support for horizontally stacked materials used in most retaining walls. Burying one third or one half of the length of the deadmen posts gives them anchoring capabilities, says Donan Engineering. Deadmen are attached to wooden and stone retaining walls through fasteners like metal ties and screws. Metal posts or rebar is added inside the hollow core of concrete block retaining walls. Unless the retaining wall is very short and mostly decorative it will need deadmen for proper support.


The retaining wall is designed to keep wet soil from sliding, but all of that moisture has to go somewhere as it runs down the slope. Many retaining walls fail because water washes out the soil directly below the retaining wall according to Albert Group Landscaping. This leaves a gap where soil escapes and eventually the wall collapses due to the lack of support below it. Installing a simple black corrugated drainage pipe, perforated and surrounded with gravel to allow water flow, directs rainfall and other moisture away safely.

Soil Compaction

Soil that looks compact and stable often compresses further under weight such as a retaining wall. If the soil around your retaining wall wasn't compact properly during the building process Cornerstone Retaining Walls says that it will shift and leave cracks and gaps in the retaining wall. Homeowners must rent a compactor from a heavy equipment store if they intend to build their own retaining wall or the structure will eventually break as the soil below it compresses and leaves a gap for it to sink into.

Weak Materials

Stacking a few landscaping timbers or concrete blocks at the bottom of a hill isn't enough to stop loose soil. While these materials do work for retaining walls in some circumstances, it's important to calculate the amount of soil the wall will be holding before choosing a material. If you want a weaker material because it is more attractive adding deadmen or adding multiple tiers instead of a single wall extends its strength according to Family Handyman.

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