Building a retaining wall
Landscaping: Tips for Your Backyard
Lay perforated drainage tubing at base Water-soaked soil is the worst enemy of retaining walls because it exerts enormous pressure behind the wall. Adding good drainage behind block or stone walls is crucial for long-lasting, bulge-free walls. Start by laying perforated plastic drainage tubing along the base of the wall slightly above ground level so it can drain to daylight. Slope the tubing about 1/4 in. per foot.