Long Island’s local rules for building — setbacks, height limits, lot coverage, septic/sewer requirements, special-use reviews, and permit procedures — vary town-by-town. If you’re planning work anywhere on Long Island, you must check the specific town code and speak with the local building or planning department before breaking ground. Below is a concise, town-by-town rundown of the 13 towns that make up Long Island (Nassau County: Hempstead, North Hempstead, Oyster Bay; Suffolk County: Babylon, Brookhaven, East Hampton, Huntington, Islip, Riverhead, Shelter Island, Smithtown, Southampton, Southold) with the most important construction constraints and where to verify rules. Each town paragraph cites the town code or official planning/building pages you’ll want to read.

Quick Summary (what to watch for across the Island)

• Setbacks, lot coverage & height are the foundations of local rules: how far improvements must sit from property lines, what percentage of the lot can be covered, and maximum building heights. These are codified in each town’s zoning or building zone ordinance. (eCode360)
• Septic / cesspool rules (Suffolk): Suffolk County has aggressive programs and rules to replace cesspools and require upgraded nitrogen-reducing systems in many areas; funding and permit programs exist. If your property is on septic/cesspool, expect extra requirements and permitting. (Suffolk County Government)
• Coastal, wetlands, and floodplain overlays: Many towns have coastal erosion, waterfront, and floodplain rules that add setbacks, elevation, and permitting requirements for shoreline properties. (eCode360)
• Historic districts / Architectural Review Boards (ARB): Several towns (notably East Hampton, Southampton and some villages) have ARB or design review processes that control exterior appearance and materials in addition to zoning. (eCode360)
• Permits, inspections, and variances: All towns require building permits and inspections; if your project conflicts with zoning you’ll likely need a variance from the Zoning Board of Appeals (ZBA) or a special permit. Expect plan sets, surveys, and sometimes foundation staking where work is near minimum setbacks. (eCode360)

Town-by-town highlights

Nassau County Towns

Hempstead

Key points: Hempstead’s Building Zone Ordinance sets district-specific height limits (e.g., many single-family districts max 30 ft / 2½ stories), setbacks, and lot-coverage rules; special exceptions and accessory building rules are spelled out in the code. Always check the specific district section for precise dimensional requirements. (eCode360)

North Hempstead

Key points: North Hempstead’s zoning code provides detailed yard and height rules (e.g., specific eave/elevation measurements in residential districts) plus off-street parking and lot-coverage tables — important for additions and accessory structures. (eCode360)

Oyster Bay

Key points: Oyster Bay enforces site-plan and building code rules through its Planning & Development documents; expect site-plan requirements for larger projects, explicit grading/drainage standards, and typical setbacks/height/coverage tables. Oyster Bay has been actively amending zoning (check recent local laws). (Oyster Bay Town)

 

Suffolk County Towns

Babylon

Key points: Babylon requires building permits for decks, sheds, pools and has clear setback tables and permit expiration rules; small accessory structures can still be subject to ZBA review if they exceed area or conflict with setbacks. See the town’s FAQ and permit pages for common thresholds (e.g., deck height & setback triggers). (Town of Babylon)

Brookhaven

Key points: Brookhaven publishes practical handouts (zoning setbacks, decks, accessory structures). Some small decks under certain heights may not require a permit, but larger decks, detached garages, and second stories do — and must meet the applicable district setbacks and bulk rules. (Brookhaven Official Website)

East Hampton

Key points: East Hampton’s code includes strict coastal, scenic and historic protections; the town often requires architectural review and has special rules for lot disturbance, building size limits, and shoreline setbacks intended to preserve rural/visual character. (eCode360)

Huntington

Key points: Huntington’s zoning and building chapters define height/area/bulk rules and include recent amendments (check local laws). The Building Dept. enforces the Town Building Construction Code (Chapter 87) for permits and inspections. (eCode360)

Islip

Key points: Islip’s planning department provides a General Zoning Standards table that lists setbacks, FARs, and coverage figures by zoning district. Arterial highway and transition setbacks sometimes supersede base setbacks — check the notes for your parcel. (Islip Town)

Riverhead

Key points: Riverhead enforces the NYS Building Code plus town zoning/land-development chapters; residential permit applications require plot plans and zoning specs, and the district maps and use tables set setbacks and permissible accessory uses. (Town of Riverhead)

Shelter Island

Key points: Shelter Island posts explicit setback tables (front often 50 ft; side/rear frequently 10–30 ft depending on structure) and requires foundation surveys for structures close to minimum setbacks. The town maintains a compact but prescriptive zoning code. (Shelter Island)

Smithtown

Key points: Smithtown’s Building Department enforces the NYS Building Code and local zoning; the town provides zoning-tables and FAQs for property owners and requires surveys/plot plans to determine setbacks. (Smithtown NY)

Southampton

Key points: Southampton’s zoning code includes coastal erosion hazard areas, septic/sewer considerations, and residential zoning overviews; the town issues guidance booklets on lot coverage, setback and disturbance limits and maintains stricter rules in certain overlay areas. (Southampton Town)

Southold

Key points: (See town code) Southold has its own zoning and coastal protections; shoreline and wetland setbacks, density controls, and septic/health rules commonly affect building approvals on East End properties. Consult the town code and planning office for parcel-specific restrictions. (eCode360)

Practical Tips for Builders, Homeowners, and Architects

1. Start with the town zoning map and district table. That tells you setback, height, lot coverage, and permitted uses for your parcel. (Town zoning pages and eCode360 entries are the authoritative starting point.) (eCode360)
2. Always get a current survey and check for overlays (floodplain, coastal erosion, wetlands, historic district) — overlays can add extra constraints or require special permits/agency approvals. (eCode360)
3. Expect septic/cesspool issues on Suffolk properties. If your property is on a cesspool, replacement/upgrades and county permits/grants may be required before you can finalize permits or certificates of occupancy. Look into Suffolk’s Septic Improvement Program and state funding programs. (Suffolk County Government)
4. Small structures still trigger rules. Decks, sheds, pools and accessory buildings have differing permit thresholds (height, footprint). Don’t assume “small” = exempt — towns publish FAQs/handouts that clarify when a permit is required. (Town of Babylon)
5. If you need relief, plan for a ZBA or special-permit timeline. Variances and special permits require public hearings and can add months to a project schedule — budget time and legal/engineering support. (eCode360)

Long Island’s 13 towns share the same broad categories of controls (setbacks, heights, coverage, septic/flood/coastal overlays, ARB/design review, permit/inspection and variance processes), but the details differ significantly by town and often by zoning district. For any planned work: identify your town and zoning district, obtain a certified survey, review the town’s zoning/building pages, and contact the local building or planning office early. That straightforward sequence will avoid expensive surprises like stop-work orders, required redesigns, or denial at the ZBA.

References

Nassau towns

• Town of Hempstead — Building Zone Ordinance (height/setback/bulk rules). (eCode360)
• Town of North Hempstead — Zoning code (yard/height/coverage tables). (eCode360)
• Town of Oyster Bay — Zoning & Site Plan Rules and Regulations. (eCode360)

Suffolk towns

• Town of Babylon — Zoning, permits, deck/shed FAQs. (eCode360)
• Town of Brookhaven — Zoning code and setbacks handout. (eCode360)
• Town of East Hampton — Zoning code (coastal/historic protections). (eCode360)
• Town of Huntington — Zoning & Building Code (Chapter 87). (eCode360)
• Town of Islip — General Zoning Standards and FAQs. (Islip Town)
• Town of Riverhead — Zoning & Building Department permit requirements. (eCode360)
• Town of Shelter Island — Setback tables and Building Department resources. (Shelter Island)
• Town of Smithtown — Zoning tables and Building Department applications. (eCode360)
• Town of Southampton — Zoning code, coastal erosion hazard areas, and residential overview booklet. (eCode360)
• Town of Southold — Town code and overlays (see town planning pages for parcel specifics). (Southampton Town)

County/Regional programs (important for septic & wetlands)

• Suffolk County Septic Improvement Program / FAQs / grant info. (Suffolk County Government)