The Market

5 questions to ask about renting or buying a basement apartment

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By Emily Myers  |
September 23, 2021 - 9:30AM

If you are renting or buying a basement apartment in New York City, including a duplex with a renovated basement, be sure to ask these questions.


You will pay a premium for views and light in New York City, so if you want a more affordable place to live, apartments on lower floors are the way to go, and basement apartments are the cheapest of the bunch. In fact basement apartments or duplexes with renovated basements are around 20 to 30 percent cheaper than apartments on higher floors. 

They may be more affordable, but basement apartments also come with risks. When the remnants of Hurricane Ida hit the city, people living in basements bore the brunt of the damage and at least 11 people died when their basement apartments flooded or walls collapsed, and residents had no time to get to an exit or climb out of a window. 

Those deaths should make you approach living in a basement apartment with extreme caution, however, some NYC basement apartments are indeed safe and habitable. It's all about knowing what to look for.

In order for a basement to be lived in or rented out as an apartment, it needs to comply with all housing codes that deal with minimum floor-to-ceiling height, a way out in an emergency, natural light and air, and fire protection. Another consideration should be the exterior walls—can they take the pressure that could be exerted from water outside the building? Collapsed walls posed some of the most serious dangers to renters in basements during the most recent flash floods.

With that in mind, here are some of the questions you should be asking if you are considering a basement apartment in NYC.

1. Is it legal? 

Some basements meet the safety requirements needed to be legal apartments, but not all. Generally the space needs to have enough light and ventilation—including windows and doors. What is enough? Every room in a basement floor must have at least one window. If you don't think you could climb out of the basement in an emergency or if the window is too high or too narrow, or if the exterior window sill is less than six inches above ground level, it's probably illegal.

Other requirements: The ceiling height cannot be below seven feet and in many cases, walls must be damp- and water-proofed.

Read up on the requirements for basements via NYC's Housing Preservation and Development and know the difference between a basement and a cellar. A cellar has more than one half of its height below curb level and usually has no windows or windows that are far too small for an adult to fit through. Cellars should never be used as a place to live. 

Another priority is to check the certificate of occupancy—the document that will tell you whether you're allowed to be living in the space at all. If the Certificate of Occupancy doesn’t match the building use when you’re renting, your landlord has no legal right to collect rent. 

2. Is it in a flood zone? 

New York City has 520 miles of waterfront and many low-lying neighborhoods so it shouldn't surprise you that many areas are vulnerable to flooding, some areas more so than others. New York City's Flood Hazard Mapper identifies large parts of Brooklyn including Red Hook and Gravesend, plus parts of Queens near Corona and Flushing as risk areas. 

"A knowledgeable broker should know what flood zone the building sits in," says Steven O.Goldschmidt, director of sales at Warburg Realty. Beyond that, he says, check the maintenance history for the building because reports of flooding should be in the minutes.

Another resource is the Federal Emergency Management Agency, which also has flood maps and information on the risks of flooding. According to their numbers, just an inch of water can cause up to $25,000 in damage to your apartment.

Just because the place you are thinking of buying or renting isn't located in a designated flood risk area doesn't mean it won't be affected by a flash flood or backed up drains. Do a news search for stories about flooding in the neighborhood, and if possible, talk to people who live in the building or on the block. 

3. Is it adequately flood proofed? 

If you're buying a duplex or townhouse with a basement, you'd be advised to have an inspection done before you go into contract. Check the seals on the windows and make sure the drains aren't clogged. Gerard Splendore, a broker for Warburg Realty. recommends carefully looking at the lower six to eight inches of the walls to see if they have been damaged, repainted, or if the baseboards are missing or warped.

"A line near floor level may indicate prior flooding, where water left a mark. Do the apartment floors or walls feel damp to the touch? Does the space smell musty or mildewed? Is there any evidence of mold?" he says.

An inspector will be looking for these conditions too but won't look inside the walls so it can be difficult to evaluate whether you have the correct waterproofing in a basement. Even more so if you are renting because an inspection isn't available to you. 

According to Daniel Gershburg, founding attorney of Konner Gershburg Melnick, it's not enough for buyers just to have an inspection. You want to have a contractor or architect who can evaluate the materials used, how they were installed, and tell you if the waterproofing is good enough. Ask for the invoices for the work that was done.

Sounds extreme? Gershburg says sellers of resale apartments and developers selling below-grade units may well find it difficult to get the prices they want unless they are ready to volunteer this type of information going forward. He says buyers are well informed about the impacts of climate change, and this level of due diligence may become the norm.

Think of weatherproofing as the hottest new amenity. Buyers "will care less about a common area with a pool table and more about the energy efficiency rating and the resiliency of the building itself," Gershburg says. 

A contractor or architect can evaluate the information and tell you whether the waterproofing is good enough to deal with the next five floods that hit the city. You can also check with the Department of Buildings about whether any work has been done recently on the drains in the building. If it's up to code there will be typically be permits and filings. 

Even if the waterproofing is up to code, remember New York City's drainage infrastructure is over a century old. When the sewage system backs up it won't be a question of what waterproofing is installed in the walls. A review of the perimeter of the property is also important, Splendore says. An external inspection can "reveal drains that are in working order, or appear older or are clogged with broken or no grates to prevent debris from entering the pipes," he says. 

4. Can you get insurance?

Whether or not you can get insurance—and how expensive it is—will be an indicator of the risk of buying or renting a basement apartment in certain parts of the city. 

"Reach out to flood insurance companies and ask them what coverage will cost—that’s where you mitigate as much risk as possible," Gershburg says

5. Are you ok with less light?

Apartments in brownstones don't get a huge amount of light, but basement apartments take it to another (low) level.

Even if you think you're ok with the level of light in the space, you might want to consider whether you (or those living with you) might benefit from light therapy—the practice of sitting in front of a light box to address seasonal light deficiency. It’s a relatively easy and affordable way to beat the basement blues. 


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Emily Myers

Senior Writer/Podcast Producer

Emily Myers is a senior writer, podcast host, and producer at Brick Underground. She writes about issues ranging from market analysis and tenants' rights to the intricacies of buying and selling condos and co-ops. As host of the Brick Underground podcast, she has earned four silver awards from the National Association of Real Estate Editors.

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