Batter
The slight backward lean of a wall toward the slope it's holding back. Most segmental block walls on the North Shore are built with a 1/8 inch to 1/2 inch batter per course. The lean makes the wall stronger by pushing the load down into the base instead of straight out toward the front. A wall with no batter at all is more likely to bow forward over time.
Base course
The bottom row of block, set into the compacted gravel base. It's the most important course in the entire wall. If the base course isn't level and properly bedded, every course above it will be wrong. We typically bury the base course one block deep below grade for walls under 4 feet, and deeper for taller walls.
Cap block
The finishing block at the top of the wall. It's wider than the wall blocks and gives the wall a clean visual line. We adhere caps with concrete adhesive so they don't shift. Skipping caps to save $300 is one of the cheapest tells that a contractor is cutting corners.
Cambridge Pavingstones
A retaining block manufacturer based in New Jersey, widely used on Long Island. Their product lines include Pyzique, MaytRx, and Olde English. We use Cambridge on roughly half our jobs. Their Pyzique line in the Toscana blend is one of the most popular looks on the North Shore.
Course
One horizontal row of block. A 4-foot tall wall is typically 6 to 8 courses depending on the block size.
Daylight outlet
The end of a drainage pipe that exits the ground at a lower elevation, allowing water behind the wall to drain to a visible point (the ground surface, a dry well, or a storm drain). A drainage pipe with no daylight outlet is just a buried tube full of water. We've torn out walls where the prior contractor capped both ends of the drain pipe. Yes, really.
Deadman anchor
An older method of stabilizing a retaining wall using horizontal beams or members extending back into the slope and anchored. Mostly used on timber walls. Modern segmental walls use geogrid instead, which is faster, cheaper, and more reliable.
Drainage stone
Crushed stone (typically 3/4 inch) used as backfill behind the wall. It's called "clean" because it doesn't have fines (powder), which would clog the drainage. We use a minimum of 12 inches of clean stone behind every wall we build.
Engineer's stamp
A licensed professional engineer's seal on the wall plans. Required on Long Island for most walls over 4 feet, and for any wall where soil or grade conditions make the design non-standard. The stamp costs $400 to $1,500 depending on the complexity. We have working relationships with two local PE firms.
Footing
The compacted gravel layer that the base course of block sits on. Typically 6 to 12 inches deep depending on wall height. The compaction matters as much as the depth. We compact in 4-inch lifts with a plate compactor.
Free-standing wall
A wall that isn't holding back any soil — typically a sitting wall around a patio or a property line wall. Built differently than retaining walls; doesn't need geogrid or the same drainage spec.
Frost line
The depth below grade that the ground freezes in winter. On Long Island the frost line is around 36 inches. Footings should be either fully above frost (with proper drainage to prevent ice lensing) or buried below frost. Half-and-half is what gets walls in trouble.
Geogrid
A plastic mesh that extends horizontally from between courses of block back into the slope behind the wall. It mechanically ties the wall to the soil mass, dramatically increasing the wall's resistance to overturning. Required on most walls over 4 feet. Skipping it is the #1 cause of wall failure on Long Island.
Geotextile fabric
A fabric layer placed between the drainage stone and the native soil. It allows water through but blocks soil particles, preventing the drainage system from clogging over time. Non-woven is the right type for behind a wall. Woven is for under driveways.
Gravity wall
A wall that holds back soil purely by its own weight, with no geogrid or other reinforcement. Most short walls (under 3 feet) are gravity walls. Once a wall gets over about 4 feet, gravity alone usually isn't enough.
Lift
A horizontal layer of compacted backfill behind the wall, typically 4 to 8 inches thick. You compact one lift, place the next course of block, lay the next lift, compact, and so on. Skipping lifts and dumping backfill all at once is how walls end up settling unevenly.
Linear foot (LF)
The unit retaining walls are usually priced in. A 50-foot wall is "50 LF" regardless of height. Most quotes break out price-per-LF separately for different heights.
Nicolock
A retaining block manufacturer based on Long Island (Lindenhurst). Their Olde Greenwich line is one of the most popular blocks on the North Shore. We use Nicolock on roughly the other half of our jobs.
Perforated pipe
4-inch PVC or HDPE pipe with holes along its length, laid horizontally behind the wall to collect water from the drainage stone and carry it to a daylight outlet. We use rigid 4-inch perforated PVC, never the corrugated black flex pipe (which collapses and clogs).
Plate compactor
The machine we use to compact the base and each backfill lift. Looks like a small concrete mixer with a flat metal plate on the bottom. The jumping jack is a different tool used in tight spaces and trenches.
Segmental retaining wall (SRW)
The technical industry term for a wall built of stacked concrete block units (Cambridge, Nicolock, etc.). About 80% of new residential retaining walls on Long Island are SRWs.
Setback
Two meanings. (1) The slight backward step between courses of block, which creates the wall's batter. (2) The required distance between the wall and the property line under your local zoning code. Always check setbacks before building near a lot line.
Slope stabilization
Engineering work to prevent a slope from eroding or sliding. A retaining wall is often the main component, but slope stabilization can also include drainage swales, planting, geocells, or soil nails. On Long Island's North Shore, slope stabilization jobs are common on the harbor-facing lots.
Soil pressure
The horizontal force the retained soil exerts on the back of the wall. Higher walls, wetter soil, and steeper slopes behind the wall all increase soil pressure. Geogrid and proper drainage are the two main ways we manage it.
Step-down
A section of the wall that drops in height to follow the grade. We design step-downs in full block units so the geometry stays clean. Avoid contractors who fudge step-downs with cut block — it looks unprofessional and weakens the wall.
Tiered wall
Two or more walls stacked vertically, with a planting strip or terrace between them. Tiered walls can sometimes replace one tall wall that would need an engineer's stamp. The trick is the spacing — too close and they act as one wall structurally, just with a weaker connection.
Timber wall
A wall built of pressure-treated 6x6 or 8x8 timbers. Mostly a 1970s and 80s technology on Long Island. Lifespan is typically 20 to 25 years. Most of the timber walls we're called to look at today are at end-of-life and need full replacement, usually in block.
Toe
The front face of the bottom course of the wall. The toe is what bears the load. If the toe kicks out, the wall is failing.
Wall pin
The plastic or fiberglass pin that aligns one course of block to the course below it. Cambridge and Nicolock systems both use pins. Skipping pins is a way some shortcut contractors save 5 minutes per course. Don't.
Weep hole
A drainage gap left in masonry walls (typically poured concrete or stone) to let water behind the wall escape. Segmental block walls drain through the joints between blocks, so they don't need weep holes. If you see a contractor quoting weep holes on a block wall, ask questions.