If your plan is to expand a Manhattan townhouse in a landmark district you will need to get approval from the Landmark Preservation Commission(LPC) before getting a Department of Buildings Permit. You should hire an architect who is familiar and has worked before with the LPC so that they can best advise you. Generally, you might be able to build an extension on the back of the house that will match what the LPC has approved for neighboring properties but they may or may not let you go as high as they did. Also, materials used in the renovation will influence their decision to approve or deny including down to the types of windows and colors of the window frames.
Putting a penthouse on the roof might also be acceptable but it can not be visible from the street. So you might have 3000 square foot of air rights left on an Upper West townhouse on park block but the likelihood that you will be able to use them all will be small.
The Author- 
Brian Silvestry , a licensed real estate broker, has been selling residential and commercial real estate since 1999. He has sold in every neighborhood from Battery Park City to Washington Heights.
466-468 Columbus avenue is currently a 3 story building with retail that once housed the vegan restaurant, Blossom and Flywheel. The owners had submitted designs to create a new 8 story mixed use building on the site. The design was critiqued by the LPC and did not receive approval. The design team of BKSK will tweak their proposal and return at a later date.
Landmarks Wants Refinements for BKSK’s New Mixed-Use Building at 466-468 Columbus Avenue, Upper West Side
The Mount Morris Historic district has now expanded to include practically all of the buildings from Adam Clayton Powell boulevard to Lenox avenue from 118th street to 123rd street. The expansion includes many beautiful brownstone homes as well as some apartment buildings. Homes that fall within a historic district need the LPC approval to do work to their exteriors. Over the last few years, historic districts are attempting to expand to preserve the character of neighborhoods.
Typical brownstones within the Mount Morris Historic district ask over $3mm and it’s only a matter of time before one sells for over $4 million.
What do you think of the expansion?
A homeowner, Nina Jusiniano, who resides in Queens bought her Astor Row townhouse 28 years ago for just under $30k. Since then the house has laid vacant, cemented shut and may be causing issues for the neighbor’s home attached to it. According to DNAInfo, the owner is selling a home in South Ozone Park, Queens to raise funds to complete a renovation. The house in Queens, according to the article has been for sale for about a year. The Landmark Preservation Commission is asking a judge to fine the owner $5,000 per day until she renovates the home. The owner believes the home is worth as much as $900k. Given that homes on Astor Row would probably go for close to $3 million or more if in good condition, that $900k is low. The owner believes that $300,000 will be enough to renovate the home. That number seems low as well to do a proper renovation in a historic district given it has been abandoned for nearly 30 years. What’s your opinion? Should the LPC be suing owners to get them to maintain their properties or are they overstepping their boundaries?
News about the NYC real estate residential and commercial markets provided and interpreted by an industry veteran licensed since 1999. Brian Silvestry of BSRG Inc. Licensed real estate broker