Retaining Wall Failure: Common Causes We See in Washington State

Most retaining wall failures are caused by poor installation — not bad materials.

The most common problems we see include:

• poor or insufficient drainage behind the wall

• inadequate base preparation

• not installing enough of the wall below grade (burying blocks)

• improper backfill material

• lack of reinforcement on taller walls

• poor compaction during installation

  
  

In Washington’s wet climate, hydrostatic pressure puts enormous stress on retaining walls. Without proper drainage and compaction of base material, walls eventually begin leaning, separating, and failing.

Warning signs include:

• leaning or shifting

• sinking sections

• separating blocks

• erosion of material under base block when not properly buried below grade

  
  

A retaining wall is a structural system, not just stacked blocks. Proper excavation, drainage, and reinforcement are what determine whether a wall lasts one year or several decades.