Avoiding the 7 Blunders of Flood Mitigation

June 02, 2016

Water Street--Originally only one block long, Water Street was extended during a city landfill program in 1692. The landfill was necessary to hold back the erosion of the island's shore and the waters of the East River, which washed over this aptly named street during high tide.

In October 2012, Superstorm Sandy once again put many Downtown streets under water, along with other entire neighborhoods throughout the five boroughs. Historic storm surges and floodwaters revealed the inadequacy of New York’s building stock to survive the next one and what some say is inevitable sea level rise.

Liam Michael Bennett - Water Street

Image Credit: Liam Michael Bennett

New York City has 538 miles of coastline and more than 84,000 buildings worth over $129 billion are actually below the 100 year flood plain. Flood hazard regulations were already established in 1983 so that communities in compliance could gain support from FEMA’s National Flood Insurance Program (NFIP) in the event of a disaster.  The storm sparked FEMA to update their Flood Insurance Rate Maps (FIRMs), as well as change what could be built and what the new value of those properties are worth.

As a result, developers’ insurance companies and the Department of Buildings (DOB) continue to look for better resiliency and compliance with NYC Building Code, FEMA and other standards such as ASCE 24.

Whether you are buying, selling, or renovating, you should be aware of these 7 Blunders:

7. My building is not near the water. Flood Zones are mapped by FEMA’s NFIP program to establish the elevation of the flood plain, which often stretches far inland when the terrain is low-lying. Note that new neighborhoods were remapped into flood zones after Sandy, so know where your property stands today.

6. My building is exempt because it’s not too much work. The codes offer relief from full flood hazard compliance for properties that pre-date flood regulations. However, when repairs and upgrades exceed half the market value of the property, also known as a “substantial improvement,” the entire structure is required to make substantial upgrades, potentially resulting in lost rentable space below the floodplain. Even if your building does not pass that threshold, some work could still be considered a new non-compliance and therefore not exempt.

5. My building should get a variance from BSA. The hardening of grand-fathered building stock with occupied basements and cellars is tricky business. Do you want to implement upgrades to satisfy your flood insurance carrier, but find yourself limited by the code as to the type of flood-proofing you are allowed? Before you start racking up attorney fees on time–consuming variance proceedings at the Board of Standards and Appeals (BSA), get a handle on the measures you can actually take that are in line with the code.

4. Know what to leave underwater. The common understanding of code requirements is to elevate building mechanical, electrical and plumbing systems, thus creating awkward placement of emergency generators, fuel storage tanks, boilers other mechanical systems in spaces where prime real estate should normally be. Know which components are safe and compliant to leave below the floodplain in order to maximize your leasable square footage.

3. Leaving height and floor area bonuses on the table. If grandfathered portions of your building were destroyed by Sandy, know what the redefined zoning parameters are so that you can rebuild and elevate such conditions to retain your property’s full value. For new development, floor area and roof coverage bonuses are now available to offset the spatial requirements of flood resiliency features.


Image Credit: NYC Dept. of City Planning

2. My exits are not required during a flood. You already know that exits cannot be blocked, and YES you still need exits open during a flood. Designers continue to struggle with implementing flood mitigation systems without having exit doors blocked by flood shields or held shut by hydrostatic pressure. Knowing where, when and how to elevate exits can help to maximize valuable square footage while preserving life safety.

1. Flood barriers are the answer. Not always… You may feel satisfied with your flood mitigation product that requires human intervention. Although it might be within budget, satisfy your flood insurance carrier, and work with your building design, the devil is in the details of emergency planning. Items like storage, manpower during a crisis, and knowing when to pull the trigger to install are critical. Develop an Emergency Action Plan (EAP) and see if it makes sense.

There is nothing worse than having spent the money for the protection, but not being able to put it up in time for the flood. There are other systems that should be explored.


Vidaris Code Advisory provides Code and Zoning interpretations and Expediting services to the development community.  Its team led by former NYC Buildings Commissioner, Robert LiMandri, along with other former regulators, offer a more informed perspective for new and existing development – including flood mitigation services.