Why is Drainage Backfill Important?

Author: Touré Foster

Posted in: Drainage | Landscape Construction

Why is Drainage Backfill Important?

If you are building a retaining wall on your property, there is more to it than assembling the wall itself. A properly built retaining wall needs to be engineered in a way that it lasts. This requires that your wall has proper drainage so it doesn’t erode. And drainage backfill is essential for ensuring your retaining wall continues to do its job for a long time.

Before we jump into why drainage backfill for a retaining wall is important, let’s get on the same page about what backfill is, the purpose of a retaining wall, and how to ensure proper drainage.

What is backfill?

Backfill is the soil behind a retaining wall. There are many acceptable backfill types, including wall rock, drainage stone and retained soil. Regardless of the material, a retaining wall must have a compacted backfill to promote free draining.

What is a retaining wall?

A retaining wall is a structure whose purpose is to hold back soil when there’s a significant elevation change on your property. Since water can’t pass through most retaining walls, proper drainage is extremely important.

Importance of drainage

Without proper drainage, pressure builds up behind the wall. This pressure is called hydrostatic pressure, and it can cause the wall’s structure to crack or bulge. And these issues will be costly to you, as they’ll ultimately lead to your wall failing.

Ensure proper drainage

To get the to heart of this post, drainage backfill is important because it lets water flow directly towards the wall instead of building up above the native soil.

To ensure proper drainage, you must pile up approximately 12 inches of granular soil at the rear of the retaining wall. This backfill allows the water to penetrate the soil and flow towards the wall instead of pooling. Next, you need to install a perforated pipe along the inside bottom of the wall or drill weep holes.

If you choose to install a pipe, it must be perforated, which means it has small holes along the pipe that allows water to enter and exit. As a result, excess groundwater will drain and be released away from your property.

If you decide on weep holes as your drainage method, you should drill them through the wall. Weep holes allow the water to flow through the wall and away from your property, which mitigates water build-up.

Why You Should Hire a Professional

If you’re considering installing a retaining wall on your property, it’s important to hire a professional. You need someone to build your wall who understands how to properly design a retaining wall on your property. Otherwise, you may face some costly problems in the future.