What goes behind a retaining wall, layer by layer

The face of the wall is the part you pay for. The back of it is the part that decides how long you keep it.

Buried base course

The bottom course sits below finished grade on compacted granular. A wall built on the surface has nothing resisting the toe when pressure builds.

Clear drainage stone

A zone of angular clear stone directly behind the block lets water travel down instead of saturating soil against the face. Round pea gravel does not interlock and is a poor substitute.

Filter fabric

Between drainage stone and native soil. Without it, fine particles migrate into the stone, it clogs, and within a few years you have a wall holding wet clay.

Perforated pipe that daylights

At the base of the stone, sloped to somewhere it can actually discharge. A pipe that stops in soil is decoration.

Compacted backfill

In lifts, same as any base. Loose backfill settles, and the surface above the wall dips within a season.

Ask to see the back of the wall before it is buried. Any contractor doing it properly will be happy to show you.

Wall construction