Beacon, NY Accessory Apartment Rules: What the Code Actually Says (2026)

By Spenser McCoy

Beacon permits one accessory apartment per single-family lot, citywide, as of the 2022 zoning amendment that moved ADUs from special-permit review to a more direct approval path. You do not need a variance to add one if your lot is a standard single-family lot and your project fits the dimensional rules below.

Who qualifies

Owner-occupancy is required. The property owner has to live in one of the two units on the lot and sign an affidavit to that effect at building permit application. This is not optional. If your plan depends on renting out both the main house and the ADU while you live elsewhere, Beacon's code doesn't allow it.

Size limits (and where most guides get this wrong)

This is where the code splits into two tracks, and where the "50% of the principal building" figure floating around online comes from a draft proposal that never became law.

• Unit inside or attached to the principal home: capped at the basement footprint plus 30% of the finished floor area above the basement. This is a formula tied to your specific house, not a flat number.

• Unit in a detached accessory building (a converted garage, or a newly constructed structure): minimum 200 sq ft, maximum 1,000 sq ft.

A newly constructed detached accessory apartment is explicitly contemplated by the current code, not just garage conversions. The 2025 amendment specifies that a newly constructed building containing an accessory apartment must sit at or behind the front line of the single-family dwelling. That's the setback rule that matters most for a new-build backyard unit.

Parking

As of the 2025 amendment, there is no required off-street parking space for an accessory apartment. Before 2025, the code required one. If you're working from an older guide or a neighbor's five-year-old permit file, this is one of the details most likely to be stale.

Rental use

Long-term rental is permitted. Short-term rental is not, under any circumstances, for either the main house or the accessory unit once an accessory apartment exists on the lot. Beacon has been tightening STR enforcement, not loosening it. If income optionality is part of your plan, plan for a stable tenant, not a weekend booking calendar.

The Plus One ADU grant

Beacon is a participating municipality in the Dutchess County Plus One ADU Program, administered by Hudson River Housing with New York State HCR funding. Income-qualified homeowners can apply for a construction grant. Hudson River Housing's own materials aren't fully consistent on the cap. Their program page states up to $125,000; other HRH documents cite $112,500. Confirm the current figure directly with Hudson River Housing before you build a budget around it. The program also carries a 10-year affordability covenant if you take the grant: the unit has to remain long-term housing at a set affordability level, verified by site visits, for a decade.

What the code doesn't settle for you

§223-24.1 tells you what's allowed citywide. It doesn't tell you your lot's specific setback and yard requirements (those come from the Schedule of Regulations tied to your zoning district), whether your existing accessory structure's footprint and age qualify it for the accessory-building size track, or whether a proposed new-build ADU trips the Architectural and Community Appearance Board of Review threshold (required if it sits within 10 feet of a property line and within 20 feet of a neighboring dwelling). Those are site-specific questions. They're also exactly the questions a feasibility study exists to answer before you spend money on plans for a project that turns out to need a variance you didn't see coming.

Beacon's code is more workable than most Hudson Valley municipalities right now: no parking requirement, a clear owner-occupancy path, and state grant money on the table. The risk isn't the ordinance. It's building a plan on a guide that has the statute number wrong.

Find out what's actually buildable on your Beacon lot. Schedule your discovery call today and learn how a feasibility study can help you work from fact not assumptions.

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