ADU · Westchester County
Can you build an ADU in Mamaroneck, NY?
Town of Mamaroneck has 17 districts. 15 districts allow ADUs with occupancy restrictions, 2 do not. Check your address to confirm the district that applies to your parcel:
What the Mamaroneck code indicates by district
The table below shows how each district treats ADUs, alongside the lot and setback standards that govern a second unit. District boundaries and conditions vary, so treat this as a starting point and confirm the district that applies to your parcel.
| District | Min lot | Setbacks F / S / R | Max height | ADU |
|---|---|---|---|---|
| One-Family Residence | 1.1478 ac | — | 35 ft | Occupancy restricted |
| One-Family Residence | 0.6887 ac | — | 35 ft | Occupancy restricted |
| One-Family Residence | 0.2296 ac | — | 35 ft | Occupancy restricted |
| One-Family Residence | 0.3444 ac | — | 35 ft | Occupancy restricted |
| One-Family Residence | 0.4591 ac | — | 35 ft | Occupancy restricted |
| Two-Family Residence | 0.1148 ac | — | 35 ft | Occupancy restricted |
| One-Family Residence | 0.1377 ac | — | 35 ft | Occupancy restricted |
| One-Family Residence | 0.1722 ac | — | 35 ft | Occupancy restricted |
| Garden Apartment | 0.0803 ac | — | 35 ft | Occupancy restricted |
| Attached Residence | 0.0574 ac | — | 35 ft | Occupancy restricted |
| Tower Apartment | 0.0344 ac | — | 70 ft | Occupancy restricted |
| Business - Mixed Use Business | 1.8365 ac | — | 60 ft | Occupancy restricted |
| Light Industry | — | — | 30 ft | No |
| Business Residential | — | — | — | Occupancy restricted |
| Service Business Residential | — | — | — | Occupancy restricted |
| Urban Renewal | 0.9183 ac | — | 44 ft | Occupancy restricted |
| Recreation | 50 ac | — | 35 ft | No |
ADUs vs. short-term rentals in Mamaroneck
No local short-term-rental law on record - which is not the same as permission for Town of Mamaroneck. No local STR ordinance specific to the Town of Mamaroneck found as of Jun 2026; standard town zoning and building codes apply. These are separate questions from whether you can build an ADU — a unit you're allowed to add isn't automatically one you're allowed to rent nightly, so check both.
Good to know
- Residential lot minimum0.0344–1.1478 ac — an ADU still has to fit the district's lot and setback envelope.
- UtilityCon Edison territory.
- Building dept(914) 381-7830
- Last reviewed2026-06-08
ADU FAQ — Mamaroneck, NY
Are ADUs allowed in Mamaroneck, NY?
Town of Mamaroneck has 17 districts. 15 districts allow ADUs with occupancy restrictions, 2 do not. Check your address with the free ADU checker, or confirm with the building department at (914) 381-7830.
Do I need a special permit for an ADU in Mamaroneck?
No district in Town of Mamaroneck requires a special-use permit for an ADU - 15 districts allow ADUs with occupancy restrictions, 2 do not. Site-plan review or a building permit may still apply.
Can I use an ADU as a short-term rental in Mamaroneck?
No local short-term-rental law on record - which is not the same as permission for Town of Mamaroneck. ADU occupancy and short-term-rental rules are separate: an ADU you can build isn't automatically one you can rent nightly. Confirm both before you count on STR income.
What an ADU costs to build in Mamaroneck
Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $235k–310k at a standard finish, and the per-square-foot rate comes in above a full house because the kitchen, bath, panel and heating plant cost the same either way. See the full cost to build an ADU in Mamaroneck, priced by size.
More on Mamaroneck: Full zoning for new construction · ADU build cost · House build cost · All Westchester County towns
ADU information for Town of Mamaroneck is compiled from the municipal code (last reviewed 2026-06-08) and provided for decision-support only — not legal or architectural advice. ADU eligibility, size, owner-occupancy and permit conditions vary by district and often carry exceptions; verify with the building department at (914) 381-7830 before relying on any answer. Source: Offsite / Aldo zoning dataset, municipalData.js.