How to Build a Retaining Wall

Build a solid wall that holds back soil.

A retaining wall holds back soil to create level space or manage a slope. A short decorative wall is a doable DIY project, but the base and drainage are what keep it from leaning or failing over time.

Build a solid base

Dig a trench and lay a compacted gravel base, levelling it carefully — the first course sets the whole wall, so take your time. A buried first course adds stability. Each block course steps back slightly into the slope for strength.

Drainage is critical

Water building up behind a wall is the main cause of failure. Backfill behind the wall with gravel and include a perforated drain pipe at the base to carry water away, plus landscape fabric to keep soil from clogging the gravel.

Know the limits

Walls over about 3 to 4 feet, or walls holding up a driveway or structure, usually need engineering and a permit — the forces are large and failure is dangerous. For tall or load-bearing walls, hire a pro.

Frequently asked questions

How do I build a retaining wall that lasts?

Lay a compacted, level gravel base, step each course back into the slope, and — most importantly — backfill with gravel and a drain pipe so water can't build up behind the wall.

Do retaining walls need a permit?

Walls over about 3–4 feet, or ones holding up a driveway or structure, usually need engineering and a permit. Check local bylaws before building a tall wall.