Accessory dwelling unit under construction on a Long Island lot

Alec's Construction builds and legalizes accessory dwelling units in Commack, Suffolk County — basement and lower-level apartments, garage conversions, dormered second floors and additions — working out of the yard in East Patchogue. Most of what people call an ADU here is an apartment inside the house they already own, and a lot of those already exist and need to be made legal. That is winter work.

Accessory Apartments in Commack

Commack straddles the Town of Huntington and the Town of Smithtown, and the accessory apartment programs are different — Huntington's in particular has been actively funding ADUs through the state's Plus One program, which is a real reason to find out which side of the line you are on. The 1960s and 1970s colonials and splits sit on lots with room for a garage conversion or a basement apartment, and the bigger lots on the Smithtown side sometimes have room for a detached unit.

Bigger Lots, More Options

On the larger lots in this part of Suffolk an accessory apartment can be a basement fit-out, a garage conversion, an addition, or — where the zoning allows it — a detached unit on its own footprint. That is a genuine choice, and the right answer depends on who the apartment is for. A parent wants single-level living with a step-free entrance; an adult child or a tenant is happy with a basement or a converted garage; a rental with real income potential wants its own front door and no shared walls.

Each option has a different permit path and a different build season. The basement and the garage are winter work. The addition and the detached unit are a spring start with the winter spent on plans and the permit.

What the Town Asks a Dwelling Unit to Have

  • A compliant egress opening in every sleeping room — net clear opening, sill height and well where it is below grade
  • Ceiling height that meets the habitable-space minimum, measured under the beams and ducts, not between them
  • A fire separation between the apartment and the main house at the shared floor, wall and stair
  • Smoke and carbon-monoxide detection in both units, interconnected
  • A kitchen and a full bath, with the plumbing and electrical inspected
  • Its own exit to the outside
  • The owner living in the house, and the accessory apartment permit with its renewal cycle
Framed and insulated Long Island basement wall going up in winter

Permits in Commack

Commack straddles the Town of Huntington and the Town of Smithtown, and the two do not file the same way. Huntington requires plans sealed by a licensed architect or professional engineer for alterations over ten thousand dollars; Smithtown does not have the same threshold. The accessory apartment permit sits on top of the building permit — two processes, one address — and the rules differ by town and by village. We confirm which authority governs from the tax map, then read the current rules for that authority, then walk the house against them. It saves months.

The Winter Plan

The interior legalizations run straight through the winter, because none of the work depends on the weather. For a new build — a dormer, an addition, a detached unit — the winter is when the survey, the drawings and the permit application get done so the framing can start as soon as the ground allows.

Free walkthrough in Commack. Alex walks the space against the code, lists what passes and what does not, and you get the list and the photographs whether or not you hire us.

Frequently Asked Questions

Is my Commack house eligible for Huntington's ADU grant?

Only if the address is in the Town of Huntington, which about half of Commack is — the rest is Smithtown, and Smithtown runs its own separate accessory apartment program. The Town of Huntington has participated in the Plus One ADU program, and the rounds open and close, so eligibility is a question with a date on it. We confirm the town from the tax map first, then the current program status, then look at the house. The winter is when the application and the plans get done.

Do I have to live in the house to have an accessory apartment?

In every Suffolk town we work in, yes — the accessory apartment permits are written around owner-occupied houses, and the owner signs an affidavit to that effect. The permits also typically renew on a cycle rather than lasting forever. The specific rules differ by town and by village, and we confirm them for the actual address rather than generalise.

What does an ADU need that a finished basement does not?

A compliant egress opening in every sleeping room, a fire separation between the unit and the main house, interconnected smoke and CO detection in both units, a kitchen and a bath that pass inspection, ceiling height that meets the code for habitable space, and its own means of exit. A finished basement family room is held to a lower standard on most of those. The gap is what a legalization closes.

What is the difference between legalizing an apartment and building one?

Legalizing means the space already exists and functions as an apartment — a finished basement, a lower level, a converted garage — and the work is bringing it up to what the town requires for a dwelling unit and getting the accessory apartment permit. Building one means creating the space. Legalization is almost always interior work and it is what we schedule through the winter.

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This guide is written by the crew that does the work. See Alec's ADUs service — accessory apartments, garage conversions and grant paperwork. Licensed and insured on Long Island, one crew start to finish, free walkthrough and a written estimate inside 48 hours.

Booking the cold months now: we also handle Additions & New Construction and Bathroom Remodeling.

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