Keep Cats Off Your Flat Roof

Tired of waking up at 3 a.m. to cats racing across your flat roof-or finding claw marks and cat mess on the membrane? You’re not alone. In Brooklyn, where every flat roof sits just one fire escape or fence-hop away from a neighborhood cat’s favorite hangout spot, this is a surprisingly common problem. I’m going to walk you through exactly how cats are reaching your roof, what damage they’re actually doing, and the humane, roof-safe ways to keep them off without hurting your building or the animals.

Cats Love Flat Roofs-Your Roof Doesn’t Love Their Claws

If you live under a flat roof in Brooklyn, chances are you’ve heard the middle-of-the-night sprint of neighborhood cats overhead-or found evidence of their visits in paw prints, fur, or worse. While the occasional cat won’t destroy a well-built roof, regular traffic, claws, and mess can damage delicate membranes, block drains, and wake you up at 3 a.m. You can discourage cats humanely without hurting them or your roof.

Why people want cats off their flat roofs:

• Scratches on EPDM, TPO, or coated surfaces that are already aging
• Waste and hair collecting around drains and corners, encouraging odors and clogs
• Noise at night when cats run, fight, or knock things over on the roof
• Concerns about cats falling, getting stuck, or ending up on neighboring property

On a Bed-Stuy three-family I worked on last spring, the owner had been dealing with at least four different cats using her roof as a litter box and boxing ring. She’d tried sprays, orange peels, even a fake owl. Nothing worked until we figured out where the cats were actually climbing from and addressed those entry points directly.

First: What Not to Do (for Cats and for Your Roof)

Before we get into what works, let’s clear out what doesn’t-and what can actually damage your roof or hurt cats in the process.

Avoid these common reactions:

• Throwing objects or spraying harsh chemicals onto the roof-dangerous for cats and can damage membranes
• Laying down broken glass, nails, or other cruel deterrents that create liability and pierce roofing
• Using generic animal-repellent powders or liquids that may stain, attack rubber, or wash into drains
• Blocking drains or edges with improvised barriers that trap water and cause ponding

We’ll stick to: Humane, roof-safe strategies-limiting access routes, adding light-touch deterrents, and, where necessary, more robust physical barriers designed not to harm animals or your roof system.

Step 1: Figure Out How Cats Are Reaching Your Flat Roof

Cats rarely jump straight to the top. They climb via fire escapes, fences, trees, balconies, sheds, neighboring roofs, or low extensions. If you skip this step and only focus on the roof surface, determined cats often just change their path and keep coming.

I’ve seen this play out a dozen times: somebody installs a motion-activated sprinkler on the roof itself, thinking it’ll scare cats away. But the cats just come up a different side of the building or wait until the batteries die. You need to find the route first.

Look for these access routes from ground or windows:

• Fire escapes or exterior stairs that lead to the roof or a low parapet
• Trees or large shrubs close enough for cats to jump from branches to the roof
• Fences, sheds, or backyard structures they can climb and then hop from
• Ledges, bay windows, or rear additions that create a stepping-stone path
• Neighboring roofs at similar height with easy crossings over shared walls

In Sunset Park, I worked on a rowhouse where cats were using a backyard tree to jump onto a one-story extension, then walking along the parapet straight onto the main flat roof. Once the owner pruned back three overhanging branches-maybe a $150 tree service call-the traffic dropped to nearly zero overnight.

Step 2: Start with Low-Impact, Humane Deterrents

Once you know the routes, start with gentle, reversible options. These work best on neighbors’ well-fed pets who are just exploring. Feral or very determined cats may need stronger measures.

Roof- and cat-safe options to try:

Motion-activated lights: Aim fixtures so they don’t shine directly into neighbors’ windows. These work especially well if you mount them near the fire escape landing or fence top where cats are climbing.

Ultrasonic or sound deterrent devices: These should be weather-rated and installed so their mounts don’t puncture the membrane. Not all cats react, and some people or pets may hear them, so use with discretion. I’ve had mixed results-some buildings swear by them, others see no change.

Scent deterrents at access points: Place cat-safe repellents (often citrus-based or specific commercial products) near likely entry spots off the roof-on fences, at tree bases, or on lower surfaces-not directly on the membrane. Reapply after rain.

Environmental tweaks: Remove food sources (e.g., open trash, bird feeders directly above the roof) and cozy cat spots like old cushions or stored items that might invite them to hang out. On a Crown Heights walk-up, the landlord realized someone had left a tarp and some canvas on the roof that basically created a cat fort. Cleared it all, and traffic dropped immediately.

Step 3: Use Physical Barriers-Where They’re Safe and Allowed

The most reliable way to keep cats off is to make access awkward or impossible. Because cats are agile and persistent, the surest long-term solution is to remove or block their climbing routes and landing spots. On a flat roof, this often means modifying fences, trees, or parapet caps rather than the roof surface itself.

Examples of roof-friendly barriers:

• Topping key sections of backyard fences with smooth, rounded capping or roller-style barriers that are hard to grip
• Pruning branches that overhang or nearly touch the roof edge-coordinated with neighbors and any tree regulations
• Installing sloped or slightly overhanging metal/wooden toppers on low walls or sheds that cats currently use as launch pads
• On accessible roofs used as decks: designing railings and privacy screens without climbable horizontal bars

In Bushwick, I worked with a landlord who installed a simple 6-inch aluminum angle cap along the top of his rear fence, sloped outward at about 45 degrees. Cats would climb to the top, hit that slippery angled surface, and slide right back down. Cost him maybe $180 in materials and two hours of labor. Cats stopped using that fence entirely within a week.

Check rules and relationships first. In Brooklyn, you’ll want to avoid anything that could be seen as a hazard over shared fences or party walls. Talk to neighbors, and when in doubt, keep barriers on your side and focused on preventing climbs-not harming animals.

Protecting the Roof Surface from Cat Damage

Even if you can’t eliminate 100% of cat traffic, you can minimize the wear they cause and protect vulnerable spots on your flat roof.

If some cat traffic is unavoidable:

• Add walkway pads or pavers in common travel paths (used for people too), so claws are less often in direct contact with membranes
• Avoid leaving loose roofing granules, peeling coatings, or bubbled patches that practically invite scratching
• Fix any soft or delaminating spots promptly-cats will investigate and can worsen them
• Keep food and bedding off the roof: you don’t want to encourage cats to stay, groom, or scratch there

Be careful with “cat deterrent” mats. Some spike or bristle mats meant for fences or gardens can puncture soft roofs if used incorrectly. If you experiment with these, keep them off the membrane-use them at ground-level access points or atop sturdy solid caps, not directly on the roofing.

I’ve seen a few DIY attempts where someone glued plastic spike strips directly to an aging EPDM roof. The adhesive attacked the rubber, and the spikes concentrated stress points that eventually tore. If you’re putting anything on the roof surface, it needs to sit on top of protective pads or pavers, never glued or screwed through the membrane.

Special Cases: Your Own Cats vs Neighborhood Cats

The strategy changes depending on whether you’re dealing with your own pets or the broader neighborhood cat population.

If they’re your cats:

• Consider supervised roof/deck access only, with harnesses or enclosed “catio” structures set on protective pads over the membrane
• Provide attractive alternatives at ground level or in a secure yard space, so the roof isn’t their main playground
• Make sure litter boxes and food stay inside or at ground level; don’t train them to see the roof as their bathroom or dining area

If they’re neighbors’/stray cats:

• Focus on limiting access (fences, trees, side walls) and removing reasons to linger (food, warm cluttered corners)
• Talk to neighbors if a specific cat is often on your roof-sometimes adjusting feeding spots or adding a catio on their side solves it
• If you suspect feral cats, consider contacting local TNR (trap-neuter-return) groups; stabilizing colonies can reduce roaming behavior over time

On a Williamsburg two-family, the upstairs tenant had an indoor-outdoor cat who loved sunbathing on the flat roof. We built a small enclosed catio frame right outside her window, set it on rubber paver tiles over the membrane, and gave the cat supervised access through a window gate. She got her outdoor time, the roof stayed protected, and the downstairs neighbor stopped hearing paws at night.

Cats on the Roof as a Roof Health Warning

If a cat can get there, water might too. Routes cats use-loose ladders, low wall gaps, sagging gutters, nearby trees-often line up with places where water collects or where past roof work wasn’t ideal. When we’re called about cats on a flat roof, we also look at drainage, parapets, and access points through a leak-prevention lens.

What a roofer might check while you’re tackling the cat issue:

• Condition of parapet caps and edge metal near cat access points
• Drains and scuppers that could be clogging with debris and fur
• Membrane wear in high-traffic corners and along routes cats (and people) use most
• Junctions between low extensions and main roofs or neighboring walls

I’ve found more than one failing parapet cap because the owner called me to deal with cats. Turns out the cats were climbing a fence, hopping onto a shed, and walking straight across a cracked and open parapet joint. Fixed the cap, sealed the access, solved two problems at once.

What You Can Try Yourself vs When to Call a Roofer

Most of the access-blocking and deterrent work you can handle on your own. But some tasks-especially anything near the roof edge or involving the waterproofing system-are safer and smarter to leave to a pro.

Safe, DIY-friendly actions:

• Identifying likely cat routes from the ground or from windows
• Trimming small, reachable plants on your property (within safety and legal limits)
• Installing simple, reversible ground-level deterrents or light fence caps
• Reducing attractants: food, open trash, cozy clutter near access points

Tasks for a roofing/building pro:

• Working near roof edges, parapets, and high walls
• Installing or modifying parapet caps, railings, or rooftop barriers on or near membranes
• Assessing whether cats have damaged roof surfaces or flashings
• Designing any rooftop enclosure, deck, or protection layer so it doesn’t compromise waterproofing

Keeping Cats Off Flat Roofs – Quick Q&A

Can cats actually damage a flat roof membrane?
A healthy EPDM, TPO, or modified-bitumen roof will usually withstand occasional cat traffic. The bigger risk comes from repeated scratching on already brittle areas, punctures from claws on older or coated surfaces, or debris and waste clogging drains. If your roof is aging, it’s worth checking any spots where cats regularly travel.

Will commercial cat repellents hurt my roof?
Some may be fine; others may stain, leave residues, or contain solvents not friendly to certain membranes. Always check product labels for roofing compatibility, avoid petroleum-based products on rubber, and test in a small, inconspicuous area-or ask a roofer before widespread use.

Are anti-bird spikes okay to use for cats on a flat roof?
Not directly on membranes. Spikes can puncture or concentrate load on soft surfaces. If used at all, they should be mounted to solid masonry, metal caps, or separate brackets, not glued or screwed through roofing.

Could I install netting above the roof to keep cats off?
In some cases, yes-but it needs proper support so it doesn’t sag onto the roof, collect debris, or act like a sail in high winds. Netting supports must be detailed not to pierce or overstress the waterproofing; this is a design task for a pro.

Do cats on my roof mean anything is wrong structurally?
Not necessarily. They may just see it as a quiet place to hang out. But if they’re using obviously sagging areas, bent gutters, or leaning ladders, those are worth checking for structural and safety reasons anyway.

Need Roof-Safe, Humane Ways to Keep Cats off Your Brooklyn Flat Roof?

We can help you:

• Assess whether cats have already damaged your flat roof or drainage points
• Suggest roof-friendly access changes and barrier details tailored to your building
• Coordinate with deck, railing, or enclosure plans so your roof stays watertight
• Combine cat-deterrent measures with a broader flat roof health check

Want to protect your roof and keep the cats safe too? Contact FlatTop Brooklyn for a flat roof and access assessment. We work on flat roofs across Brooklyn-brownstones, rowhouses, and small apartment buildings-where cats, people, and weather all compete for roof space. Our job is to keep that space durable, quiet, and as cat-free as you reasonably want it to be.