NYC Renovation Chronicles

NYC Renovation Chronicles: When that perfect combination is not

By David Katz  | January 20, 2011 - 6:50AM

In NYC, where square footage can be a proxy for happiness, many people with the means to do so will jump at the opportunity to annex a neighbor’s apartment. As an added bonus, in terms of New York real estate, the sum is worth more than the parts, with larger apartments commanding as much as two times per square foot more than smaller ones

But beware: Just because two apartments share a wall, it doesn’t mean they always form a perfect union. Combinations can get complicated. Before slipping that non-refundable check under your neighbor’s door, make sure you consider the following:

What do you have in common?

Obviously, when combining two apartments, it is critical to know precisely how much wall is shared between the units and whether there are any immovable utilities such as gas or plumbing risers located inside it. 

A few years ago, a couple came to me with two adjacent apartments and some great ideas about how to combine them. Upon review of the apartments we discovered that there was a large unused elevator shaft buried between them. Factoring this in, along with building pipes that could not be relocated, they were left with a single 42-inch-wide space between the foyer and a bedroom as the only means of connecting the apartments. 

Kitchen work

Make sure your budget allows for at least some kitchen work. Building code dictates that even in combined apartments, only one kitchen is permitted, so combinations always include the demolition of at least one of them. 

Naturally it is always cost effective if you can keep the remaining one intact. But it is unusual that the new layout will function well with a kitchen suited for a smaller apartment. And with the additional space, chances are, that like every combination client I have ever worked with, you will want a more open arrangement that connects the kitchen to an informal dining or family room. 

The wet over dry issue

All board members in NYC are rightfully paranoid about water damage, so they require extensive waterproofing in any room where there is plumbing. Despite this requirement, many co-op and condo buildings rigidly prohibit the extension of wet rooms such as kitchens, bathrooms or laundry rooms, above dry ones.  

I had one job where the board president lived below my client. Even though the building did not have a strict wet over dry policy, he made the approvals process go on endlessly. So if a primary intention of yours is to create an en-suite master bath equipped with a double vanity, Japanese soaking tub and generous steam shower, make sure your downstairs neighbor’s rare book library isn’t below it.

Light and air calculations

When your architect submits drawings to the Department of Buildings for a permit, he or she is required to include light and air calculations. 

By law, all bedrooms must have window area equal to ten percent of their floor area. So a room that is 100 square feet has to have a legal window of at least 10 square feet. (This is why there are so many L-shaped studios in the city and why you often see plans with rooms labeled study, office or storage instead of bedroom.) 

Lot line windows – windows that are on the side of the building above a lower adjacent building – are not considered legal windows because theoretically, they can be covered if the neighboring property is built up. Many combinations have limited window area relative to the size of the apartment. And very often, some of the windows are lot-line windows, meaning you cannot legally count them as bedroom windows. 

While no one from the DOB will come check to see how you are occupying your space after you have moved in, your new luxury four-bedroom might actually be a two bedroom with lots of storage--which is how you'll have to advertise it when you sell.

Climate control

Radiators and through-wall AC units are typically distributed to serve particular room layouts. Any reorganization of rooms will very likely require that existing units be relocated or new ones installed. 

With radiators, since all this work is internal, it is a lot less complicated than with through-wall AC units which affect the building envelope. In landmarked districts, this will add some time to the application process as all exterior work must be reviewed by the Landmark Preservations Commission.

Moving up

Vertical combinations necessarily involve the construction of a new stairway, the location of which will largely depend on what the building structure allows. 

Assuming the apartment’s hallway doors are maintained at both levels for exiting in an emergency, the internal stair is referred to as a “convenience stair” and is not required to comply with any regulations.

A code consultant once told me we could get away with a ladder and a bat pole (as in “to the bat pole Batman!”), though I have been hard pressed to find a client willing to go that route.

The bottom line

Rarely do any of the factors noted above amount to deal-breakers on their own. But knowing your budget and what it will buy is essential. Likewise, it is important to understand what the layout possibilities are. New Yorkers have a way of adapting to unusual floor plans, particularly in exchange for an extra bath or more shoe storage. But you will probably be disappointed if you are expecting a mansion and end up with a maze. 

David Katz ( has been practicing architecture in New York City for the last 20 years. Detail oriented, nervous and a little neurotic,  he specializes in co-op and condo renovations.

Disclaimer: Information provided herein is not to be construed as professional advice. Readers are urged to consult with a licensed architect regarding their specific circumstances prior to undertaking any renovation work. (We do not want any buildings falling down!)

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