Do I need a permit for that? A room-by-room checklist

The honest answer to whether you need a permit is almost always 'it depends' — but the pattern behind that answer is consistent enough to walk through room by room, and consistent enough that you can usually predict it yourself once you have seen it.

The underlying question is never 'how big is this job'. It is whether the work touches structure, egress, systems, the exterior, or the legal use of the space. A small job that touches one of those needs a filing; a large job that touches none of them often does not.

Relocating the sink, adding a dishwasher where there was no supply, moving the gas line for a range, or adding circuits for new appliances all trigger a filing. So does taking out a wall to open the kitchen into a living space, which is a structural question before it is a design one.

Replacing cabinets in the same layout, swapping a countertop, retiling a splashback or changing an appliance for a like-for-like unit on the existing services generally does not.

Bathrooms are the room where owners are most often caught out, because a full renovation that looks cosmetic almost always is not. Moving a toilet, shower or basin means plumbing work that is filed. Waterproofing a wet area, altering ventilation, or changing the layout in a way that affects the fixture count all point the same way.

Retiling an existing shower, replacing a vanity in the same position on the same services, or changing taps and fittings generally does not require a filing.

Any wall removal, floor opening, new opening in a load-bearing element, or change to a load path needs engineering and a permit regardless of which room it is in. This is a structural question, not a cosmetic one, and it is the category where the consequences of getting it wrong are most serious.

The same applies to anything affecting egress — stairs, means of escape, door swings on a fire route — and to anything that changes the number of dwelling units or the legal use of a space. Converting a basement into habitable rooms is a use question and one of the most common unfiled alterations in New York.

Work on the facade, the roof, windows, or anything visible from the street is usually filed, and in a historic district it is reviewable by Landmarks as well. Even a like-for-like window replacement can be reviewable where the profile or material is part of what is protected.

This is also where the parallel approvals live — scaffolding, sidewalk sheds, street use — which have their own applications and their own timelines.

In a co-op or condo, there is a second approval that is not the city's: the board's. Alteration agreements typically require drawings, insurance from the contractor, agreed working hours, and often a deposit — and boards meet on their own schedule, which can be the longest lead time in the whole project.

Board approval and a city permit are separate requirements, and the board's usually has to come first. If you are renting, the landlord's consent is the equivalent gate, and it is worth having in writing before you spend anything on drawings.

The cost of confirming with a professional is a phone call. The cost of a stop-work order mid-project, with open walls, a paid crew and a filing that now has to be made retroactively, is not comparable.

Unpermitted work also follows the property. It surfaces at the worst possible moment — when you sell, when you refinance, or when you file for something else entirely — and curing it later is always more expensive than filing it at the time.