A retaining wall looks like a stack of block or stone, but the part that decides whether it lasts is almost entirely underground and behind it. Across Bergen County we see the same story over and over: a wall that looked great the year it went in starts leaning, bulging, or cracking a few winters later. Here's what actually keeps a retaining wall standing, and what to think about before you build one.
Why retaining walls fail
Nearly every failed wall we're called to comes down to one of three things:
- Water pressure behind the wall. Saturated soil is heavy. When water has no way out, it pushes on the back of the wall with every storm. This hydrostatic pressure is the number one reason walls bulge and tip.
- A poor base. A wall set on loose topsoil or uncompacted fill will settle unevenly. Once one section drops, the courses above it start to separate.
- Not enough reinforcement for the height. Taller segmental block walls need geogrid reinforcement layered back into the soil. Skipping it to save time is one of the most common shortcuts we see.
What's happening underground in North Jersey
Much of northern Bergen County sits on glacial till and clay-heavy soil mixed with cobbles and boulders. Clay holds water and expands when wet and frozen, which adds pressure behind a wall. That's why proper excavation and soil replacement matter more here than in sandy areas. Frost is a factor too: in North Jersey the frost line is roughly 36 inches, and freeze-thaw cycles will exploit any weak spot in a wall's base or drainage.
Choosing a wall type
- Segmental concrete block: The most common residential choice. Modular, durable, and engineered for drainage when installed correctly. Taller walls need geogrid.
- Poured concrete: Very strong and good for tight spaces or structural applications like a driveway cut, but it needs proper footings and weep holes or drainage behind it.
- Natural stone and boulder walls: A great fit for wooded Bergen County lots. Heavy boulders often come right out of the excavation on site, which can save hauling costs.
- Timber: Lowest upfront cost, but wood rots in contact with wet soil. We generally steer clients toward stone or block for anything meant to last.
What a properly built wall includes
On every wall we build, the work below grade includes:
- Excavation down to firm, undisturbed soil, with poor soil removed
- A compacted crushed-stone base, leveled course by course
- The first course buried below grade for stability
- Clean crushed stone backfill directly behind the wall so water can drain
- A perforated drain pipe at the base, run to daylight or to a drainage system
- Filter fabric to keep soil from clogging the stone
- Geogrid reinforcement where the height and load call for it
If a contractor's quote doesn't mention drainage stone or a drain pipe, ask about it. It's the single biggest predictor of whether a wall will still be straight in ten years.
Do you need a permit?
It depends on height and what the wall is holding back. In New Jersey, taller walls (commonly those over about four feet, measured from the bottom of the footing) and walls supporting a load such as a driveway, parking area, or structure typically require a permit and often an engineered design. Some towns also regulate walls near property lines, wetlands, or steep slopes. We always confirm requirements with the local building department in towns like Franklin Lakes, Wyckoff, and Mahwah before a project starts.
Plan grading and the wall together
A retaining wall changes how water moves across a property. Water that used to sheet across a slope now gets collected at the top or the base of the wall. That's why we plan the wall alongside the grading for the rest of the yard, so water is directed somewhere useful instead of into a neighbor's yard or back toward your foundation.
The bottom line
A good retaining wall is mostly excavation, base preparation, and drainage, with the block or stone on top. Spend your budget where it counts and the wall will outlast the landscaping around it. If you're planning a wall in Bergen County, reach out for a free site visit and we'll walk the slope with you.
Frequently asked questions
How long does a retaining wall last?
A properly built segmental block or stone wall with good drainage can last decades. Timber walls typically last far less because the wood rots in contact with wet soil.
Why is my retaining wall leaning?
The most common causes are water pressure building up behind the wall, a base that has settled, or missing geogrid reinforcement on a taller wall.
Do I need a permit for a retaining wall in New Jersey?
Taller walls, commonly those over about four feet, and walls that support a load like a driveway typically require a permit and often an engineered design. Check with your town's building department.