Are you thinking of building a retaining wall on your property? Or do you already have one and want to make sure it lasts for a long time? Either way, you need to pay attention to one crucial aspect: retaining wall drainage.
A retaining wall drainage system is what keeps water from accumulating behind the wall and causing problems like cracking, shifting, or collapsing. But how do you design, install, and maintain a good retaining wall drainage system?
How tall of a retaining wall needs drainage?
As a general rule of thumb, any retaining wall that is higher than 4 feet should have some form of drainage system installed. This is because the pressure of the soil behind the wall increases with height, and can cause the wall to crack or collapse if there is no way for the water to escape. However, this rule may vary depending on the specific conditions of your site.
For example, if you have a clay soil that retains water, you may need drainage even for a lower wall. On the other hand, if you have a sandy soil that drains well, you may not need drainage for a higher wall. Similarly, if you have a high water table that causes water to seep through the wall, you may need drainage regardless of the height. Conversely, if you have a low water table that keeps water away from the wall, you may not need drainage at all.
The best way to determine if your retaining wall needs drainage is to consult a retaining wall contractor who can assess your site and design a suitable drainage system for your wall. They can also advise you on the best materials and methods to use for your wall construction and drainage installation.
Why drainage is important to a retaining wall?
Drainage is important to a retaining wall because it prevents water from accumulating behind the wall and exerting pressure on it. Water can cause soil erosion, which reduces the stability and support of the wall. Water can also create hydrostatic pressure, which pushes the wall outward and causes cracks, bulges, or collapses. To avoid these issues, you need to provide a way for water to escape from behind the wall and prevent it from seeping into the soil.
There are several methods to ensure proper drainage for your retaining wall, such as installing perforated pipes, gravel backfill, weep holes, or drainage mats. These methods allow water to flow through or around the wall and prevent it from building up. By choosing the right materials and techniques for your retaining wall drainage, you can extend the lifespan and performance of your wall and protect your property from water damage.
Problems with retaining wall drainage
Retaining wall drainage is not something you want to neglect. If you don’t pay attention to how water flows around and through your wall, you might end up with some serious headaches. Here are some of the common problems that can arise with retaining wall drainage and how they can affect your property.
- Water accumulation: If water pools behind your wall, it can create hydrostatic pressure that pushes against the wall and weakens it over time. This can cause cracks, bulges, or even collapse of the wall. Not to mention, standing water can also attract mosquitoes and other pests that can ruin your outdoor enjoyment.
- Soil saturation: If water seeps into the soil behind your wall, it can make it heavier and more prone to sliding or shifting. This can also compromise the stability of the wall and cause it to lean or tilt. Additionally, saturated soil can freeze and thaw, creating more pressure and movement on the wall.
- Structural damage: If water infiltrates the joints or cracks of your wall, it can erode the mortar or glue that holds the blocks or stones together. This can weaken the integrity of the wall and make it more susceptible to cracking or breaking. Moreover, water can also cause rusting or corrosion of any metal components in your wall, such as rebar, anchors, or ties.
Best drainage material for a retaining wall
When it comes to retaining wall drainage, not all materials are created equal. You want to choose a material that allows water to flow freely behind the wall, preventing hydrostatic pressure from building up and causing damage. Here are some of the most common options for drainage materials and how they compare:
- Gravel: This is a popular and inexpensive choice for drainage, as it creates a porous layer behind the wall that lets water seep through. However, gravel can also get clogged with dirt and debris over time, reducing its effectiveness. You may need to clean or replace the gravel periodically to maintain good drainage.
- Perforated pipes: These are pipes with holes along their length that collect and divert water away from the wall. They are usually installed at the base of the wall, along with gravel or another filter material. Perforated pipes can be very effective at preventing water accumulation, but they also require proper installation and maintenance to avoid leaks or blockages.
- Geotextile fabrics: These are synthetic fabrics that act as filters, allowing water to pass through while keeping soil particles out. They are often used in combination with gravel or perforated pipes to enhance drainage performance. Geotextile fabrics can help prevent clogging and erosion, but they can also degrade over time due to exposure to sunlight or chemicals.
Conclusion
Without proper drainage, your wall could suffer from water damage, soil erosion, hydrostatic pressure, and even collapse. That’s why you need to follow the tips and guidelines we’ve shared with you, such as choosing the right materials, installing weep holes and pipes, backfilling with gravel, and maintaining your drainage system regularly. By doing so, you’ll ensure that your retaining wall drainage holds up, rain or shine.
