If you're staring at a leaning, bulging or cracked retaining wall behind your Voorhees, Marlton or Mullica Hill home, you're not alone. Most failed walls have nothing to do with the blocks — they have to do with what's behind them.
1. No drainage behind the wall
Water is a wall's number-one enemy. A proper retaining wall has a perforated drain pipe at the base, gravel backfill behind the blocks, and an outlet that daylights downhill. Skip that and hydrostatic pressure pushes the wall over within 5–10 years.
2. No geogrid on taller walls
Anything over 3–4 feet needs geogrid — a structural mesh that ties the wall back into the soil. Without it, walls lean forward as the soil behind them creeps. We see this constantly on DIY and budget contractor walls in Camden, Burlington & Gloucester County.
3. Wrong base
Walls need 6–12 inches of compacted ¾" clean stone, not dirt and not screenings. A bad base equals settlement, equals the wall splitting at a joint within a few seasons.
4. Wrong block for the height
Lighter pinned blocks are fine for a garden bed. Anything load-bearing or over 3 feet needs a heavier engineered block system. "It looked the same at the store" is how walls get rebuilt after 5 years.
5. No engineering on tall walls
In NJ, walls over 4 feet typically need engineered drawings and often a permit. Skipping that step is how walls fail catastrophically — and your homeowner's insurance won't cover an unpermitted structure.
How to build one that lasts 30+ years
- 6–12" compacted stone base, level and tight
- Engineered block system rated for the wall height
- Geogrid every 2–3 courses on tall walls
- Drainage pipe + gravel backfill, daylighted to a real outlet
- Capstones glued with proper masonry adhesive
- Permits and engineering for anything over 4 feet