Wet over dry describes a kitchen, bathroom, or laundry placed directly above a room in the apartment below that was not built to get wet, such as a bedroom or a living room. Most New York co-op and condo boards prohibit it. In practice, a kitchen or bathroom can usually be moved only to a spot that sits above an existing wet area in the unit below, and whether a specific move is allowed depends on the building's alteration agreement and on where the plumbing risers run.
This guide explains the rule, when a relocation can be approved, and how to plan around it. Grandeur Hills Group handles these questions as part of our apartment renovation work in Manhattan and Brooklyn.
What the Wet-Over-Dry Rule Is
Apartment buildings are designed with kitchens and bathrooms stacked vertically, floor over floor, around shared plumbing risers. The rule keeps that stacking in place. Water can leak from any fixture, drain, or supply line, and when it does, it goes down. If the room below is a kitchen or bathroom, it has a waterproofed floor, a drain, and finishes that can be dried and repaired. If the room below is a bedroom, the leak lands on a plaster ceiling, a wood floor, and someone's furniture.
The rule is not a city code requirement in most cases. It is a building rule, written into the alteration agreement or the house rules, and enforced by the board and its engineer during the review of your plans. Some buildings prohibit any wet-over-dry condition. Others allow limited exceptions with added protection. You have to read your building's agreement to know which applies.
Why Boards Enforce It
The board's concern is liability and damage to other units. A leak from a relocated bathroom damages the apartment below, and the building, the owner above, and the owner below can end up in a dispute over who pays. Boards also have a duty to the building's plumbing system as a whole. Moving fixtures away from the risers means longer horizontal drain runs, and those need slope to work. In a slab-floor building there is often not enough depth for the slope, so the floor is raised or the ceiling below is lowered, and both of those affect neighbors. Boards also know that an exception granted once will be cited by the next applicant, so most prefer a clear rule.
What Counts as a Wet Area
The definition is set by the building, but the usual list is:
- Kitchens, including the sink, the dishwasher, and any water line to a refrigerator or ice maker.
- Bathrooms and powder rooms, including all fixtures.
- Laundry areas with a washing machine, whether in a closet or a dedicated room.
- Wet bars, pantries with a sink, and any space with a floor drain.
A powder room is a wet area even though it has no shower. A laundry closet counts too, so adding a washer to an apartment that never had one usually has to sit over a wet area below, unless the building allows it with a drain pan and a leak-detection shutoff. Dry areas are everything else: bedrooms, living rooms, dining rooms, offices, closets, and hallways.
When a Relocation Can Be Approved
The clearest case is a move that keeps the new wet area over an existing wet area below. Enlarging a bathroom into a closet that sits over the neighbor's bathroom, or swapping a kitchen and a bathroom that are both over wet areas, is usually acceptable in principle, though the drain and vent routing still has to work.
Moves that put a wet area over a dry room are refused in many buildings. Where a building does allow them, the usual conditions are:
- A full waterproof membrane under the new floor, extended up the walls and tested with a flood test before the finishes go in.
- A drain routing that reaches an existing riser with proper slope and venting, confirmed by a plumbing engineer.
- Leak-detection sensors with automatic shutoff valves on the supply lines.
- A written acknowledgment from the owner accepting responsibility for damage caused by the relocated fixtures, often carried into the alteration agreement so that it binds future owners.
Owning the unit below does not change this. The board still reviews the plan against the building's rules, because the units may be sold separately later.
What the Board Will Ask For
The request is made through the standard alteration process, which we describe in our guide to renovating a co-op or condo in NYC. For a wet-area relocation the package usually includes:
- The alteration agreement, signed, with the deposit and fees the building requires.
- Drawings by a registered architect or engineer showing the existing and proposed plans, the location of the wet areas in the unit below, and the plumbing riser diagram.
- A letter from the architect or engineer confirming that the drain routing, slope, and venting work and that the waterproofing meets the building's standard.
- Insurance certificates from the contractor and from each licensed plumber and electrician.
- The plumbing filing with the Department of Buildings, which is required for relocated fixtures regardless of the building's rules.
The board's engineer reviews the package and issues comments. A wet-area relocation almost always draws them, so expect at least one round.
Combinations and Gut Renovations
Apartment combinations raise the issue in reverse. Joining two units usually leaves more bathrooms than the home needs and a second kitchen that the building requires you to remove. Removing wet areas is generally welcomed, but it means capping lines at the riser, not just under the floor. If a former kitchen becomes a laundry or a bar, it is still a wet area and stays subject to the rule. We cover this in Combining Two Apartments in NYC.
In a gut renovation, owners often want to redraw the plan from nothing. In a New York apartment the risers and the wet areas below are fixed, and the plan has to be built around them. That is why we investigate the building and the unit below before we draw. Our guide to the NYC gut renovation timeline explains where that investigation sits in the sequence.
Planning a Layout Around It
- Find out what is below you. Ask the managing agent for the floor plan of the unit below. Wet areas on that plan are where your wet areas can go.
- Locate the risers. Your architect or the building's engineer can identify the plumbing stacks and how far a fixture can move from each while keeping the drain slope.
- Start with the fixtures, then the rooms. Place the sink, the toilets, and the showers where they can drain, then plan the layout around those points. A kitchen can be reorganized a good deal while the sink stays near the riser. A bathroom is more constrained, because the toilet drain has the least room to move.
- Read the alteration agreement before the first sketch. Design only for the exceptions the building actually allows. This is the single step that saves the most redrawing.
What to Ask Before You Start
- Does the building prohibit wet over dry outright, or allow it with conditions?
- What is directly below each wet area in the proposed plan?
- Where are the plumbing risers, and how far can each fixture move from them?
- Will the board require a flood test, leak detection, a waterproofing specification, or an engineer's letter?
- Will the acknowledgment of responsibility carry forward to a future owner?
If you are planning to move a kitchen or bathroom, request a consultation before the layout is settled. We will review the building's rules and what sits below the apartment and tell you which moves are likely to be approved.
