Introduction to retaining walls
First, a retaining wall is a structure that retains, or “holds back,” the lateral faces of earth, water, or other materials. Retaining walls are used to prevent the erosion or collapse of higher level ground over a certain building, structure, or general area. The soil that is retained is often called fill. The word fill is also used as a verb to describe the placement of more earth behind a retaining wall to level the ground.
Retaining walls may be the answer if you’re blessed (or cursed) with a contoured lot. They can turn a steep slope into a terraced patio, creating a stair effect instead of a slope.
Retaining walls can be built from many different materials using many different techniques. There are several factors that influence which choice will be best for each situation, including cost, wall height, soil characteristics, and groundwater conditions.
In general, most municipalities require any retaining wall over four feet in height to be designed or approved by a licensed engineer. It’s important to check local building codes before starting any retaining wall project, even if it’s less than four feet tall. After all, retaining walls must be structurally sound before aesthetic appeal can be considered. The retaining wall must be able to resist the pressure exerted by the backfill, also called lateral earth pressure. This lateral earth pressure is the majority of the force that the retaining wall will have to withstand. Lateral earth pressure is determined by studying soil unit weight, soil slope, soil type (for purposes of plasticity and adhesion with clay soil types), and groundwater levels. Engineers do many calculations with these factors to determine which design to implement with the wall. For homeowners and contractors who don’t want to go through the engineering steps, it’s generally a good rule of thumb to overdo it. Many structural methods for constructing retaining earth retaining walls, at least temporarily, up to four feet high, are adequate, so most local building codes require engineering if the wall will be more than four feet high. height.
However, even seemingly adequate methods of retaining soil can fail if not constructed correctly. Many times, it is the below grade elements that can make (or break) a retaining wall. Problems including bowing, tilting, or cracking are evidence of retaining wall failure because it failed to retain dirt. Cutting costs with a bad contractor, insufficient materials, or neglecting below-grade items can become more costly over time if they need to be replaced or repaired frequently or if landslide causes damage to nearby structures. For example, erosion can cause foundation problems if dirt erodes under the foundation. This is just one example of how a retaining wall failure can cause costly problems on top of the cost to repair or replace the retaining wall.
Another aspect that is often neglected or underestimated and that can cause the failure of a retaining wall is drainage. Inadequate drainage of retaining walls can mean that water is trapped behind the wall, increasing the weight that the wall must support. Drainage holes and/or drainage pipes are usually used to discharge rainwater and groundwater behind the wall. It is important that the drainage system, whatever it is, has a filter barrier to prevent dirt from clogging the drain or drain hole.
Options for Retaining Wall Materials
· Railway sleepers: Railway sleepers, also abbreviated as railway sleepers, can be used as retaining wall material; however, as with most retaining wall materials, it must be installed correctly for it to be a solution. For example, most railroad tie retaining walls will need a substantial footer to tie the sleepers together to prevent the bottom from slipping out. Also, there needs to be perpendicular members placed on the ground behind the wall to prevent the wall from collapsing. These members, called dead men, must be at least 1.5 times as long as the height of the wall and must be placed at least every 6 feet or so. Because railway ties are made of wood (even though they are treated most of the time), there is a risk that they will rot over time or be subject to termite infestation, which can lead to a wall. weak that is likely to bulge or break. And, although there are areas for water to seep in slowly, it’s still a good idea to have a filtered drain or drainage holes designed into the wall.
Treated Lumber – Treated lumber retaining walls offer many of the same risks as retaining walls because it is susceptible to rot and termite infestation over time. It’s a labor-intensive build, but is generally light and decently strong if built properly. It is recommended to build a concrete footer to bond the wall in order to prevent it from moving. Construction typically requires a clear area to be backfilled after the wall is built, so it’s not always the best material to use if you’re replacing an existing retaining wall. This wall still needs drainage holes or drains designed in the wall. Standing water behind the wood will only increase the risk of rot.
Concrete – Concrete is an excellent material to use for retaining walls. Of course, there is a right and wrong way to build a concrete retaining wall, which makes choosing your contractor a big job. There are many different designs that can lead to a successful concrete retaining wall, but one thing is for sure: there must be a footer under the wall to ensure success. Concrete is one of the most durable man-made products known to man. Most concrete poured today is designed to last more than 50 years. In addition, concrete also offers many decorative options. In addition to a white concrete retaining wall, you can also pour a colored concrete retaining wall, stain a retaining wall after it has cured, pour in a patterned shape, apply a vertical sealing material, and pattern afterward. to pour etc. Sealing the concrete wall can result in an easy-to-maintain surface that rinses free of most of the dirt and grime.
Blocks or Pavers: Designed blocks stacked to form a wall should be as simple as building with Legos, right? No. These retaining walls must also have a significant footer to support not only the weight of the earth but also the weight of the wall. These blocks may have a unique look, but it may even be necessary to put a concrete retaining wall behind the blocks if there is a lot of lateral earth pressure. In such a case, the concrete would be the structural element, using the blocks as a visual element.
Rock or Brick – One of the favorite looks for a retaining wall is natural stone or brick. These materials generally look more permanent and traditionally elegant. However, as we have seen with the other materials, it is necessary to have a foot of concrete below ground level to support the weight and ensure the success of the retaining wall. Like architectural block or paver systems, it may be necessary to back a masonry retaining wall with a concrete retaining wall for structural support.
