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New Jersey’s topography is varied. From the steep slopes of the Watchung Mountains to the rolling hills of Hunterdon, many properties are not naturally flat. To create usable yard space, driveways, or patios, homeowners often need retaining walls.

However, a retaining wall is not just a decorative stack of stones. It is a structural dam holding back tons of soil and water. If built incorrectly, it can collapse, causing catastrophic damage. At Black Diamond Paving & Construction, we combine engineering precision with masonry artistry to build walls that stand the test of time.

Why Retaining Walls Fail You have likely seen walls that lean forward, bulge in the middle, or have crumbled. The culprit is rarely the weight of the dirt; it is hydrostatic pressure.

The Physics: When it rains, the soil behind the wall gets saturated. Water is heavy (62 lbs per cubic foot). This pressure builds up behind the wall. If the water cannot escape, it pushes the wall over.
The Black Diamond Fix: We build a "drainage chimney" behind every wall. This is a 12-inch vertical column of clean gravel directly behind the block, extending from the bottom to the top. At the base, we install a perforated drain pipe. This ensures that water falls through the gravel, enters the pipe, and exits away from the wall. No pressure build-up means no collapse.
Material Options

Segmental Concrete Blocks: Brands like Techo-Bloc, Cambridge, and Anchor offer engineered wall systems. These blocks have locking lips or pins that secure them together. They are incredibly durable and come in textures that mimic natural stone.
Natural Stone Boulders: For a rustic, organic look, we use large boulders. These rely on gravity and skilled placement to hold back the earth.
Masonry Walls: Concrete block walls faced with natural stone veneer and capped with bluestone. These are the most formal and high-end option.
Geogrid Reinforcement For walls taller than 3-4 feet, gravity alone isn't enough. We use Geogrid.

What is it? It is a high-tensile synthetic mesh. We place it between the layers of blocks and extend it back into the hillside (often 4-6 feet). The weight of the soil sits on the grid, locking the wall into the hill. The wall essentially becomes part of the slope, rather than just sitting in front of it.
Conclusion Building a retaining wall is a serious construction project. It requires excavation, drainage, and structural knowledge. Don't trust a landscaper with a pickup truck to build a 6-foot wall. Trust Black Diamond Paving, the structural experts among construction companies in NJ.