How to Build a Retaining Wall that Lasts a Really Long Time

Building a retaining wall seems simple enough. Install a footer, lay the material, backfill the area… these are obvious steps to constructing a wall. However, as any walk through a neighborhood will reveal, retaining walls crack and collapse on a regular basis. There are many reasons for why this happens – improper materials, insufficient reinforcement of the footer, poor measurements or design… But what about the drainage? In our experience this seems to be the part that many people fail to consider when constructing, well, anything.

Much of our work follows construction jobs. Many of the calls we receive are from people who built a structure a few years prior, but far too prematurely something began to leak or a wall began to fail. It is often not realized just how great the power of water can be, if not corralled properly. And yet water (and more technically, hydrostatic pressure) exerts a force on soil-retaining vertical structures that is strong enough to crack even reinforced concrete.

Water is a medium that must be given an out – if not, it will find a way. When considering how or why water might act or behave, we have to consider that it is like any other substance or creature in the world – it will always take the path of least resistance. What proper drainage does is take this into account and provide exactly that. By installing drainage at key points around a structure, you consider water’s behavior and design accordingly, so that water and hydrostatic pressure have an easy-out.

For example, when building a wall, we know that water will flow downhill. When that water reaches a wall, it will flow down vertically (but with horizontal hydrostatic pressure), until it can adjust to a more lazy route. When we install a french drain (the gravel trench drain with perforated pipe and filter fabric) we provide a nice easy channel for this water to fall into and flow away. Putting area drains along the top of the wall, to draw surface water away before it has a chance to absorb in the ground, is critical as well. Besides having these components in place, proper placement and sufficient slope are pivotal to ensuring these drainage systems work.

Top to bottom drainage is the key to success here – a french drain alone or a catch basin by itself is not always enough. When considering a retaining wall, we have to think about where all the water may come from and how it will behave once it gets there. For that reason, our construction accounts for serious drainage that covers all fronts. Water is that secret killer that may lie unnoticed for years, until suddenly a costly retaining wall is shifting and leaning or moisture is seeping into a finished basement. Whatever you do, don’t wait until its too late by considering drainage only after a structure is failing. Make sure that whatever you’re building, whether its a retaining wall or something else, that it has the necessary drainage in place to ensure it lasts for a really long time.