Flooding is becoming a more frequent and costly risk for buildings in New York City. Whether it’s a sudden summer downpour or a storm surge along the coast, the impact can be significant—disrupting daily operations, damaging property, and creating stress for both residents and building staff.
But with the right preventative approach, your board can reduce the risk and avoid costly surprises when the next storm hits.
Here’s how.
Fortify the building before water gets in
The best time to deal with flooding is before it happens. That means identifying where water could enter—and putting the right protections in place.
Install barriers where it counts
Deployable or permanent flood barriers can help protect basement doors, garage ramps, sidewalk grates, and other entry points at risk. Some buildings opt for automatic systems that rise with water levels, especially in flood-prone zones.
Prevent sewage backups
A common (and often messy) source of flooding in NYC buildings is sewer backflow. Installing a backwater valve on your building’s sewer line can keep things flowing in the right direction—away from your property.
Check your sump pumps
If your building has a basement or low-lying mechanical room, you need reliable sump pumps with battery backups. Test them regularly, especially before storm season. A pump that fails during a storm is as good as not having one at all.
Seal the cracks
Walk the property and look for gaps or cracks in foundation walls, around utility piping, or near basement windows. Waterproof sealant goes a long way in keeping water out before it becomes a problem.
Don’t let clogged drains catch you off guard
One of the simplest and most effective things you can do: make sure water has somewhere to go.
Clean gutters and downspouts regularly
Leaves, debris, and even roof gravel can block drainage. Schedule cleanings at least twice a year and after major storms. And check that downspouts channel water away from the foundation.
Inspect sidewalk and property drains
Exterior drains are your first line of defense during heavy rainfall. Make sure they're clear, functional, and not funneling water into basement stairwells.
Check basement floor drains
A simple but often overlooked item. Make sure floor drains are unobstructed and connected to a functioning system.
Don’t overlook your roof
A compromised roof is one of the most common sources of flooding in NYC buildings, especially during fast-moving storms. Even a flat roof that looks fine from the ground could be hiding problems.
Inspect for ponding, cracks, and membrane wear
Flat roofs are prone to water buildup, especially if drains are clogged or sloped incorrectly. Regular checks can help spot issues early and avoid interior leaks.
Use smart tools when needed
In some buildings, we’ve used drone photography and thermal imaging to spot hidden vulnerabilities—like standing water, membrane separation, or insulation damage—without needing to walk the entire roof. These tools are especially useful for large or hard-to-access roofs and can help catch issues before they cause interior damage.
Safeguard building systems and equipment
Even minor flooding can knock essential systems offline. Taking a few steps now can help you avoid costly, time-sensitive repairs later.
Elevate what matters
Electrical panels, boilers, water heaters, and HVAC equipment should be raised off the ground or relocated above flood-prone areas whenever possible. Some boards handle this during major capital projects, but even temporary risers or platforms can help.
Secure heavy machinery
Anything at risk of floating or shifting under water pressure should be anchored. This protects not only the equipment but the space around it.
Don’t wait to test backups
If you have a generator or water removal system, make sure it's ready for use. Power loss during a flood is bad enough—losing your backup is worse.
Make a flood response plan
Preventative maintenance is only part of the equation. You also need a plan in case a storm is on the way.
Know your flood zone
NYC’s Flood Hazard Mapper is a great place to start. Understanding your building’s specific risk level can help you prioritize improvements and insurance coverage.
Have clear emergency steps
Everyone—from your super to your board president—should know what to do during a flood event. That includes communicating with residents, shutting down elevators, deploying barriers, protecting valuables, and contacting the right vendors.
Keep the right supplies on hand
Sandbags, water pumps, flashlights, warning signage—these should be accessible and in good condition. And don’t forget batteries or fuel for any powered equipment.
Communicate with residents early
Whether through email, SMS, or lobby signage, make sure residents know what to expect, what’s being done, and how to reach building staff if needed. More guidance on resident prep here.
Stay proactive with inspections and recordkeeping
Inspections twice a year—once before summer storm season and again after winter’s freeze—can help catch small issues before they lead to major ones. Keep logs, photos, and maintenance records organized. These can be a lifeline during insurance claims or city inspections.
Take the pressure off with good planning
No one wants to be the board scrambling to lay sandbags at midnight. A little foresight now can save thousands of dollars, countless hours, and a whole lot of stress later.
From proactive planning to real-time responses during storms, Daisy helps boards keep their buildings protected, residents informed, and operations running smoothly—no matter the forecast, read more on how we handle floods here.
