# Hillside Retaining Wall NYC | Terraces & Steep Lots | NYC Retaining Walls

> Hillside retaining walls in NYC: terraced and tall walls for steep lots, including Special Hillsides and Natural Area District sites. Free site visit.

URL: https://nycretainingwalls.com/hillside-retaining-walls/

![Terraced segmental block retaining walls on a steep hillside yard on Grymes Hill, Staten Island](https://nycretainingwalls.com/images/terraced-segmental-block-walls-steep-hillside-yard-grymes-hill-staten-island-1440.webp)

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2.  [Retaining Wall Installation](https://nycretainingwalls.com/retaining-wall-installation/)
3.  Hillside Retaining Walls

# Hillside Retaining Walls in NYC

On a steep lot, the wall is only part of the job. The slope above it, the water coming down it and, in some neighborhoods, City Planning all get a say before the first block is set.

[Book a free site visit](https://nycretainingwalls.com/contact/) [Call (718) 555-0100](tel:+17185550100)

Terraced block walls on a steep yard  
Hillside lot · Grymes Hill, Staten Island

-   Walls 4 ft+ or carrying a surcharge need a DOB permit — 1 RCNY §101-14
-   Local Law 37: walls 10 ft+ fronting a public right-of-way, inspected every 5 years
-   Filing windows: Staten Island 2026 · Queens 2027 · Brooklyn 2028 · Bronx 2029 · Manhattan 2030
-   Drainage zone: clean crushed stone, filter fabric, perforated pipe that daylights
-   Segmental walls reinforced with geogrid to the engineer's design
-   Lot-line walls are shared 50/50 — NYC Admin Code §28-305.1
-   Written contract required on home improvement jobs over $500 — NY GBL §771

Last updated: October 18, 2026

[NYC Retaining Walls](https://nycretainingwalls.com/) is a licensed and insured retaining wall contractor that builds hillside retaining walls to engineered plans for steep lots across the five boroughs — terraced backyards, tall walls cut into a slope for a house or driveway, and rebuilds of old walls holding up a hillside. A hillside retaining wall carries more than the soil directly behind it: a slope rising above the wall adds load, water running down the hill collects behind it, and on the steepest ground the stability of the whole slope, not just the wall, becomes the engineering question. NYC's steepest residential ground — Staten Island's serpentinite ridge, which reaches about 410 feet at Todt Hill, the Fordham gneiss of Riverdale, and the glacial moraine through Douglaston and Little Neck — is also where special zoning districts can add a review step before a permit.

## What we do on the first visit

The first visit is free and takes about an hour, because slopes have more to read:

1.  **We measure the slope** above and below the planned or existing wall, and the total grade change across the lot, so the designer knows whether one tall wall or a series of terraces makes sense.
2.  **We look at the ground** — exposed rock, seeps and wet areas, signs of past soil movement such as tilted trees or bulging ground.
3.  **We trace the water** coming down the hill from uphill lots, roofs and the street.
4.  **We check zoning status.** If the lot is in the Special Hillsides Preservation District or a Special Natural Area District, the project may need City Planning review before DOB will issue a permit, and that changes the schedule.
5.  **We plan access.** Machines on a slope need a safe path in; some hillside work is done with small equipment or by hand.
6.  **You get a written scope and price**, with any planning and permit steps spelled out, usually within two business days.

## Terraces, tall walls and slope stability

**Terracing** breaks a large grade change into shorter walls with level ground between them. It's often cheaper per foot of height and makes the yard usable, but the tiers interact: an upper wall set too close to a lower one loads it like a surcharge, so tier spacing and height are set by the engineer, not by eye. Sloped backfill above any wall is itself a surcharge, which puts the wall in DOB permit territory at any height (1 RCNY §101-14).

**Tall single walls** are used where there's no room to terrace — a house or driveway cut into the hill. They are usually reinforced poured concrete or segmental block with long geogrid layers; see [block retaining walls](https://nycretainingwalls.com/block-retaining-walls/). On steep sites the engineer may also check global stability, meaning whether the slope could slide as a mass behind and beneath the wall.

**Water** is the constant on a hillside. Each tier needs its own drainage zone of clean ¾-inch crushed stone, filter fabric and a perforated pipe that daylights, and surface water from above has to be intercepted before it reaches the top wall. A hillside wall 10 feet or taller fronting a sidewalk or street also falls under Local Law 37's five-year inspections.

## Special Hillsides and Natural Area Districts

Two kinds of special zoning districts cover many of the city's steepest residential lots, and both can require **City Planning review before DOB issues a permit**.

-   **Special Hillsides Preservation District (Staten Island, 1987).** Covers much of the North Shore hills, including the Grymes Hill area. Its goals are reducing hillside erosion, landslides and stormwater runoff; lots with an average slope of 10% or more fall under its controls on development, grading and other site alteration.
-   **Special Natural Area Districts.** Four areas: **NA-1 Staten Island Greenbelt**, **NA-2 Riverdale** in the Bronx, **NA-3 Shore Acres** on Staten Island and **NA-4 Fort Totten** in Queens. Site alteration — regrading, removing natural features, building walls on steep slopes — is subject to City Planning Commission review.

We check district status on the first visit and build the planning step into the timeline. See the [Todt Hill](https://nycretainingwalls.com/service-areas/todt-hill/), [Grymes Hill](https://nycretainingwalls.com/service-areas/grymes-hill/) and [Riverdale](https://nycretainingwalls.com/service-areas/riverdale/) pages for neighborhood detail, and [driveway retaining walls](https://nycretainingwalls.com/driveway-retaining-walls/) for steep drives.

## What hillside walls cost

On national cost guides adjusted by the RSMeans New York City cost index of 129.1, segmental block runs **about $20–$45 per square foot of wall face**, poured concrete **about $26–$65** and natural stone **about $26–$120** (HomeGuide and HomeAdvisor, 2026). Hillside jobs add engineering (typically **about $450–$970**, HomeAdvisor × 1.29), any City Planning review, and access costs for working on a slope. Every job gets a written contract before work starts, as New York's General Business Law §771 requires for work over $500.

## What's included

-   ✓Free site visit with slope and grade-change measurements
-   ✓Special district check: Hillsides and Natural Area
-   ✓Water trace from uphill lots, roofs and the street
-   ✓Terrace vs. single-wall options, priced side by side
-   ✓Engineer coordination, including slope stability
-   ✓City Planning and DOB steps built into the schedule
-   ✓Drainage zone and outlet for every tier
-   ✓Erosion control during construction, photos at closeout

## DIY vs. cheap operator vs. a wall built properly

| Factor | DIY | Cheap operator | Built properly |
| --- | --- | --- | --- |
| Drainage behind the wall | Native soil backfill | A little gravel, no pipe | 12 in+ of clean crushed stone, filter fabric, perforated pipe that daylights |
| Footing | Set on topsoil or sod | Shallow, uncompacted | Compacted base, sized and set below the frost line to the design |
| Reinforcement | None | None | Geogrid or rebar to an engineer's design where height and load call for it |
| Permit and engineer (walls 4 ft+ or surcharged) | Skipped | Skipped or "not needed" | Stamped plans and a DOB filing |
| Local Law 37 (10 ft+ on a right-of-way) | Unknown | Ignored | Built and documented so the QRWI report goes smoothly |
| Paperwork you keep | None | A handwritten estimate | Written contract, line-item scope, closeout photos |
| Where it usually fails | First freeze-thaw seasons | Within a few years, at the drainage | Designed to carry its load for decades |

## Related resources

-   [Code Guide Do I Need a Permit for a Retaining Wall in NYC?](https://nycretainingwalls.com/guide/retaining-wall-permit-nyc/)
-   [Cost Guide How Much Does a Retaining Wall Cost in NYC? (2026 Prices)](https://nycretainingwalls.com/guide/retaining-wall-cost-nyc/)
-   [Decision Guide Concrete vs Block Retaining Wall: Which Is Better in NYC?](https://nycretainingwalls.com/guide/concrete-vs-block-retaining-wall/)
-   [Code Guide When Is the Staten Island Retaining Wall Inspection Deadline?](https://nycretainingwalls.com/guide/staten-island-retaining-wall-inspection-deadline/)

## What this work looks like

Illustrative photos of this kind of work — not a specific customer's job.

-   ![Silt fence and erosion control on a slope during retaining wall construction on Todt Hill, Staten Island](https://nycretainingwalls.com/images/silt-fence-on-slope-during-retaining-wall-construction-todt-hill-staten-island-800.webp)
-   ![Small tracked excavator cutting a level bench into a slope for a retaining wall in Riverdale, the Bronx](https://nycretainingwalls.com/images/small-tracked-excavator-benching-slope-for-retaining-wall-riverdale-bronx-800.webp)
-   ![Old stone retaining walls stepping down a hillside garden in Douglaston, Queens](https://nycretainingwalls.com/images/old-stone-retaining-walls-stepping-down-hill-douglaston-queens-800.webp)
-   ![Green serpentinite rock outcrop beside a new retaining wall on a Staten Island hillside lot](https://nycretainingwalls.com/images/serpentinite-rock-outcrop-beside-new-retaining-wall-staten-island-800.webp)

Talk to a person now.

Callback within 1 business hour. Mon–Sat, 7am–7pm.

[Call (718) 555-0100](tel:+17185550100) [Book a free site visit](https://nycretainingwalls.com/contact/)

Codes and standards we work to

-   NYC Zoning Resolution Art. XI Ch. 9 (Special Hillsides)
-   NYC Zoning Resolution Art. X Ch. 5 (Special Natural Area)
-   1 RCNY §101-14 (permits)
-   NCMA SRW design guidance

Get a number first

[Cost estimator — length × height × material](https://nycretainingwalls.com/tools/retaining-wall-cost-estimator/)

## How hillside retaining walls works, _step by step._

1.  01
    
    ### Call or send photos
    
    Photos from the bottom and top of the slope, and the address so we can check the zoning district.
    
2.  02
    
    ### Free site visit
    
    We measure the slope, read the ground and the water, check district status and plan access.
    
3.  03
    
    ### Design, review and permit
    
    Line-item price; the engineer designs the walls and we coordinate any City Planning step and the DOB filing.
    
4.  04
    
    ### Build and close out
    
    Walls, drainage and backfill built tier by tier with the slope protected, then photos and sign-offs.
    

Building on _a steep lot?_

Free site visit and a written, line-item price before any work starts.

[Book a free site visit](https://nycretainingwalls.com/contact/) [Call (718) 555-0100](tel:+17185550100)

Callback within 1 business hour · Mon–Sat, 7am–7pm

## Hillside Retaining Walls _questions._

**### Is it better to terrace a slope or build one tall wall?**

Terracing usually costs less per foot of height and gives you usable level ground, but it needs enough horizontal room so each tier doesn't overload the one below. One tall wall suits sites with no room to step back, such as a house or driveway cut into the hill. The engineer sets tier heights and spacing, and we price both options when the site allows.

**### My lot is in the Special Hillsides Preservation District. What changes?**

Lots in the district with an average slope of 10% or more fall under extra controls on development, grading and site alteration, and the work can require City Planning review before DOB issues a permit. That adds time at the start, not usually to the build itself. We check the district on the first visit and include the planning step in the written timeline.

**### Does a hillside retaining wall need a permit if it's under 4 feet?**

Often, yes. The permit exemption in 1 RCNY §101-14 covers walls under 4 feet only when they don't support a surcharge, and sloped backfill rising above the wall counts as one. Many hillside walls hold a slope rather than level ground, so they need a DOB permit with plans by a licensed engineer or architect even when short.

**### Which NYC neighborhoods have Special Natural Area Districts?**

There are four: NA-1 covers the Staten Island Greenbelt, NA-2 Riverdale in the Bronx, NA-3 Shore Acres on Staten Island and NA-4 Fort Totten in Queens. Site alteration in these districts, including regrading and building walls on steep slopes, is subject to City Planning Commission review. Separately, Staten Island's North Shore has the Special Hillsides Preservation District.

**### How fast can someone look at my wall?**

We call you back within 1 business hour during business hours (Mon–Sat, 7am–7pm) and schedule a free site visit within 3 business days. If the wall is actively moving, has dropped material onto a sidewalk, or has been rated Unsafe, say so on the call and we'll put it first.

## Related _services._

-   [![Layer of geogrid reinforcement rolled out over compacted fill behind a segmental block retaining wall under construction](https://nycretainingwalls.com/images/geogrid-layer-rolled-behind-segmental-block-retaining-wall-800.webp)
    
    ### Block Retaining Walls
    
    Segmental block walls with geogrid reinforcement — terraces, yards and replacements for failed timber walls.](https://nycretainingwalls.com/block-retaining-walls/)
-   [![New poured concrete retaining wall running alongside a sloped residential driveway](https://nycretainingwalls.com/images/poured-concrete-retaining-wall-beside-sloped-driveway-800.webp)
    
    ### Driveway Retaining Walls
    
    Walls alongside and below sloped driveways, designed for vehicle surcharge and filed with DOB.](https://nycretainingwalls.com/driveway-retaining-walls/)
-   [![Worker setting the first course of segmental retaining wall blocks on a compacted gravel leveling pad with a string line](https://nycretainingwalls.com/images/setting-first-course-segmental-block-on-gravel-leveling-pad-800.webp)
    
    ### Retaining Wall Installation
    
    New engineered walls with a proper footing, drainage zone and reinforcement — permits and plans coordinated.](https://nycretainingwalls.com/retaining-wall-installation/)

Sources

1.  [NYC Planning — Special Natural Area District](https://www.nyc.gov/assets/planning/download/pdf/plans/special-natural-area-district/snad.pdf)
2.  [Special Hillsides Preservation District (overview)](https://en.wikipedia.org/wiki/Special_Hillsides_Preservation_District)
3.  [NYC DOB, 1 RCNY §101-14 — work not requiring a permit](https://www.nyc.gov/assets/buildings/rules/1_RCNY_101-14.pdf)
4.  [Staten Island Serpentinite (Todt Hill geology)](https://en.wikipedia.org/wiki/Staten_Island_Serpentinite)

Start with _the wall._

All five boroughs. A live person answers.

[Book a free site visit](https://nycretainingwalls.com/contact/) [Call (718) 555-0100](tel:+17185550100)

Callback within 1 business hour · Mon–Sat, 7am–7pm