When building a retaining wall, or just starting with the planning process, don’t overlook the importance of having a drainage system in place.
Not only can a drainage system with your retaining wall protect your lawn and home foundations from water damage, but it can also prevent puddles of water from forming and giving nuisance insects such as mosquitos an area to breed.
Why is Drainage Important?
As it rains, the water will flow down the slope of your property and into your retaining wall. Your retaining wall will not allow water to pass through it so instead it should have options for water to be released in a controlled manner.
Drainage that does not have any easy exit points through or around your retaining wall will collect towards the bottom of the wall and can start to erode the soil your wall is built on. Over time, this can lead to damages in the wall including cracked stone, sagging areas, or even complete wall failure.
Additionally, water that is allowed to run over the top of a retaining wall can flood the lawn or garden, or even damage the foundation of buildings, on the other side. Having a drainage system in place will divert rainwater to a more suitable area of your property.
Creating Proper Drainage
Around half of the issues a retaining wall will face are caused by drainage. Ensuring your wall is properly designed and has an effective drainage system in place will ensure you have a stable and stylish retaining wall for years to come.
Some of the best tips for drainage around your retaining walls are:
- Include backfill. Around 12 inches of the space behind your retaining wall should be filled with gravel to assist in proper water drainage.
- Consider a drainage pipe. This is normally only needed if your retaining wall is built on poorly draining soil such as clay, or if the wall is more than 4 feet in height.
- Place water outlets regularly. Depending on the length of your retaining wall, placing outlets every 30 feet along the wall can help give water an easy path to escape from instead of continuing to build pressure behind the wall.
Problems Caused by Poor Drainage
Most retaining walls that fail will do so because of poor drainage. When building a retaining wall, one of the first things you need to consider is whether or not drainage is an issue in that area of your property.
As water from rain or melting snow builds up behind a retaining wall, it can cause the lower soil layers to shift or erode, and in turn the wall can start to sag or fail completely. Even if the wall doesn’t fail completely, repairs will be much more frequent in order to relieve the pressure from excess water buildup.
Retaining walls are costly to replace, so always keeping the drainage in mind before the wall is built can save you a world of headaches.