How a retaining wall handles water

When a retaining wall leans or bulges, the cause is almost always water. Soil soaked with rain is heavy, and if that water cannot drain, it pushes on the back of the wall every time it rains.

What goes behind the wall

A well-built wall has more going on behind it than in front of it:

• A compacted gravel base under the first row, set below ground level.
• Clean, crushed gravel behind the stones, not the soil that was dug out.
• A perforated drain pipe at the bottom of that gravel, with a way out at the end.
• Fabric between the gravel and the soil, so the gravel does not clog up over time.

Leaning back into the slope

Good walls lean slightly back toward the hill they hold. Block systems build this in with a lip on each block. With natural stone, we set each row a little further back than the one below.

Taller walls may need extra reinforcement or an engineer’s design, and some towns require a permit over a certain height. We check that before we quote.