cats pooping on my carport roof, any advice?

I have a carport attached to my house (which in turn is attached to houses attached to houses, I live in an urban setting. A normal person could walk the whole block on roofs, with a bit of vertical jumping). All the cats in the area are now pooping on top of the carport. Every day I wake up to 5 or 6 turd piles now. The carport is made of transparent polysomethingorother and ah, they also scratch their little feeties on it after pooping. So I get to see the piles and their little footprints and scratches.

The carport, of course, is about 2.5m off the ground and I can only access it from the edge, standing on a ladder. It's not like I can walk out there and clean it every day, it's a major production even to get a hose up there, and it doesn't support human weight.

It is spring and it's raining like nuts, with the El Niño it's forecast to continue like this for months. There is literally a sandpile across the street but the cats want to crap on my carport, I suspect it has something to do with the sand being wet.
I have a dog, but he's a dope and thinks he can attack the cats from beneath (and he might actually break through like the Kool Aid man, since he is jumping on my car to get to the cats). The cats don't care, they seem to think it's funny and it stops them not at all.
I have seen repellants, alarms, motion strobe lights, etc. Our security guy says the only thing would be to put electric fence literally everywhere, which I don't have money for (or desire either. Our shop has electric fencing everywhere and the cats still are all over the place). Ultrasonic repellers, even if they work, would probably make my dog even more insane.
The cats are semi-feral. Nobody is responsible, but I suspect many people feed them.
My kid is a biologist and says nothing is going to keep them away other than mortal solutions, which is not compatible with my organic garden and the animals who live in it (also my dog).
I thought of putting up some sort of smelly stuff but it's raining every day for the foreseeable future. I can wash off the crap every few days (if the rain doesn't get it off) and try to spray something.
The entire thing is 7m by about 5m-- too big to put the suggestions I've seen like sticky tape, spiky things, etc. I can't build a wall between all the roofs and I'm starting to feel like this is absolutely impossible, every solution has a problem.


Might anyone have any advice? Words of comfort? Want to buy an otherwise nice house in a great neighborhood?

Ugh, that's nasty. Feral cats can deposit all sorts of disease/parasites in their faeces.

Aside from lethal measures, a deterrent is needed that will survive the rain.

Do you have access to good sticky clay? Do you have access to powdered cayenne? Not the wimpy stuff that North Americans use, but the absolutely nuclear-hot ethnic stuff that will melt your face?

Perhaps you could create sticky pancakes, mixing these two elements. These would erode less quickly in the rain, especially if dried first, and might coat the roof with hot cayenne as they slowly break down.

A cat with ethnic hot cayenne stuck to its paws will be encouraged to move on.

- - - - -
Edit: A discarded carpet saturated with the above elements might do the job with less work.

Our daughter recued a dog from Mexico.  It ate all the cayene pper we had put out to keep our dog from eating stuff.

How to the cats get up on your carport?

I have read that cats do not like citrus or eucalyptus.  Try citrus peeel on the carport.

Is there any way to string a lattice work of fishing line across the top of the carport to dissuade the cats from walking across the roof?

The only thing coming to my mind is how much cats hate to walk on stuff that crinkles, like aluminum foil or crinkly plastic - but I can't figure out how to make that work on top of a carport...

This seems a bit outlandish, but hear me out.
Polysomething roofing does have a lifespan,  and you have a fierce sun in the tropical regions.....is it getting brittle due to age? Near its useful time on earth?
My idea would involve removing the current roof. Either repurpose the material or feed a hungry landfill.....no, that's not a green solution, but we all require a modicum of sanity in our lives.  
Your new roofing will be a steeply pitched affair, rendering it impossible for cats to defecate.  

Another potentially outlandish suggestion: maybe try offering the cats something even better than your roof?

Because your problem brings to mind that old permaculture adage: "not a cat problem, but a litter tray deficiency"

I.e., if you suspect they don't like the heap of sand cos it's wet, and so they're resorting to a bare roof belonging to an angry human and a dog (which doesn't sound ideal for them either), could you maybe build an accessible sheltered area somewhere, with a dedicated sandpit in it that they can use instead? It doesn't let you off the hook work-wise (you'd need to buy a pretty sturdy litter scoop too), but the cats get to do their ablutions somewhere warm and dry, your roof might be left alone, and you get to manage the situation on your terms in a more accessible location. Maybe crazy. Might not work. Just a thought.

You could perhaps start by testing the theory with a cheap covered litter tray, and if they're not adverse to that, extend to something bigger for more cats. If they still prefer the roof, you'll have learned it's probably not about that wet sand.

[Edit: spelling]

Thank you so much for all the ideas!!!

The cats are walking across all the other roofs to get to my carport roof, in case it's not clear. It is 7 meters across where the carport meets my roof (it covers the whole yard, not just one car) and kind of a lot to build fences (which I imagine the cats would just jump over?).
My entire yard is fenced in and the dog has access to it. There's not anywhere I could build a litterbox except maybe in the street?
Explaining this all makes me understand a bit more: part of the issue with our urban cats, I think, is that they don't usually touch the ground! There are LOTS of dogs that people let run wild during the day which would gladly eat a cat. They usually all go back home at night, though. There was a large empty lot up the street where I assume the cats used to hunt and do their business, but it's now being developed and is a huge mud bog instead of a field with elephant grass, lizards and rats. I'm assuming this is why they're suddenly here.

Rico Loma wrote:
My idea would involve removing the current roof......Your new roofing will be a steeply pitched affair, rendering it impossible for cats to defecate.  

Alas, I just paid a ridiculous amount to install this thing about 6 months ago!!! where's that crying emoji.... and it has a custom made steel structure that will be used even after we replace the roofing material in the future. Steeper would involve... building a second story on my house? It would probably be easier/cheaper to just move, set on fire, etc.

I do like this pepper and clay idea-- hot peppers aren't part of the local cuisine but lately there are a lot of carolina reaper sauces floating around for people to give as gifts (that's my theory, anyway... I often hear folks saying black pepper is 'too spicy', i can't imagine them eating reapers) and i have clay in my yard. i could see mixing up some balls to throw up there guerilla garden seed bomb style.

Later this morning I'm going to hose it off, at least (although I guess I'll have to tie the ladder to something.... ugh), two more turd piles this morning. I was thinking of using some sort of really smelly cleaning ingredient (powdered laundry soap?). But it is supposed to rain again tonight, so I will have new chances every day...

Carla Burke wrote:The only thing coming to my mind is how much cats hate to walk on stuff that crinkles, like aluminum foil or crinkly plastic - but I can't figure out how to make that work on top of a carport...

There is a spiky product out there that looks like... if you took those little plastic tables that hold pizza boxes up off the center of the pizza? turn them upside down and join a gazillion together, it makes a product they sell to keep cats off stuff. It is, however, 70 bucks for half a square meter and that's a lot of money, considering I'd probably have to put at least one meter deep around the edges (I figure a cat would jump up to a meter lengthwise?), 7 meters one way and 6 along the other.

Anne Miller wrote:Our daughter recued a dog from Mexico.  It ate all the cayene pper we had put out to keep our dog from eating stuff.

Ha!! I had a horse (non-Mexican, as far as I know) that ate all the wood in the barn, I tried painting everything with hot pepper and oil and it literally licked it all off the first day. I guess there's no accounting for taste....

Megan Palmer wrote:Is there any way to string a lattice work of fishing line across the top of the carport to dissuade the cats from walking across the roof?

This seems like the best idea so far. I need to think about how I can attach it without destroying my roof in the rainy season, but I suspect we can come up with something (as we're sitting around on the weekend stuck inside during the rain!!). I do like the idea of a damn cat getting caught in a NET!

Life sized coyote decoy (or whatever local predator you have) on the roof?

We've had feral cat issues. It is unbelievable (to me) how many protections can be in place for them depending on where you live. We tried a bunch of things that were less than lethal and had some mixed results. I am pretty sure one of our neighbors feeds them.

Here, once they endanger your livestock, you can use whatever method you want to get rid of them.

Like most things, it has been a cyclical issue.

Perhaps a sprinkler system with motion sensor? Cats don't like to be sprayed.....

Jackson Bradley wrote:Like most things, it has been a cyclical issue.

I'm hoping it's something that passes as the weather shifts.
They aren't protected, but most anything I might do could be construed as animal cruelty, so I'm not asking the neighbors to collaborate or anything like that (and also I'm reticent about lethal measures-- all it takes is one neighbor who has a grudge to make a complaint). Also, I'm not sure what a cat's range is, but I'd say we have about 60-80 houses within a 2 block radius. I only know the people immediately to my sides or the ones I run into at the gym. There are so many people with so many cats and almost nobody spays (costs money). Le sigh.
Early this morning I heard them out there and thought about going out there, but it was like 3:45 and maybe 35 degrees F and there was no way I was getting out of bed. Maybe tonight.

So today I got up on the ladder and got the turds down with a double-handled floor squeegee (the kind where you can attach one handle to another one, it is maybe 3,5 m), the ladder is at the down end of the slope and the hose didn't have enough pressure to shoot it downward; after I pulled them down I hosed it off and of course that led to a flood of cat-shit-slurry coming down to me on the ladder. I cleaned it up the best I could (one turd was hopelessly out of my reach unless I went up on the roof of the house and leaned on out, which isn't happening) and scatter-threw some powdered laundry soap up there, we are supposed to have another day or two of clear weather and I'm thinking if they get it on their feet they won't like it (also it's smelly, but it smells better than cat shit and piss). Not my favorite solution but it's what I can do today.
If anyone's looking for me, I'll be taking a shower in bleach. Gag.  

Tereza Okava wrote:

I'm hoping it's something that passes as the weather shifts.  

The danger is that if they've decided it's the safe spot, a weather shift may not change them.

It sounds like they are mostly doing it at night? If that were the case, would a simple light bulb lighting it all night discourage, or encourage them? I live in owl country, so a not too bright light would give the owls an opportunity for cheap dinner!

Seems like too much of a water waste to put an oscillating sprinkler on the roof. They move slowly, so the cats might learn to walk around and simply avoid it.

For getting the muck off, one of the stronger super-soakers might be helpful? We have a good power-washer, but it would knock me right off the ladder, as I don't have enough mass to counter balance it.

These cats are out there in the rain, so I don't think a weak stream of water is going to do much.

As for light, my neighbors have a spotlight in their front yard that shines right there (our houses butt up next to each other- the carport makes it so the light doesn't shine into our house, but it shines right up on top of the roofs. Then there are the streetlights. It's definitely not a dark corner!!

Yes, we have a power washer, but like you said, not safe if I'm up on the ladder, and definitely not with me doing it all alone. The guys who installed the roof said power washing was not safe with the surface... but at this point when cat claws are in the mix I think it really can't get much worse! I will have to go get the pro ladder from the shop so I can fold it into a platform, but considering that I can still not get the stink out of my nose I don't think it's going to happen again for a few days.

Coat the roof with Lego or jacks or razor-wire so that walking on it is unpleasant? Motion-sense squirter, or maybe predator noise, seems like a reasonable thing to try if such is available.

Tereza Okava wrote: I need to think about how I can attach it without destroying my roof in the rainy season

Would it be possible to attach the lines to a frame on the ground, lift onto the carport then secure all four corners to the carport so it doesn’t get blown off in strong winds?

Megan Palmer wrote:

Tereza Okava wrote: I need to think about how I can attach it without destroying my roof in the rainy season

Would it be possible to attach the lines to a frame on the ground, lift onto the carport then secure all four corners to the carport so it doesn’t get blown off in strong winds?

Let me try to visualize this-- you're thinking multiple lines of fishing line strung into posts, right? like a fence? so to hold it taut i need to have a bunch of 'middle sticks' as well. The one side I don't think the cats can access (this is the side I stand on with my ladder and cleaning supplies, sloping down from my roof toward the street), so like a wooden frame with holes drilled in it? How tall do you think the fence has to be to keep out a cat that is coming in 'downhill' along the slope of the roof? [I'm envisioning broom handle-height posts]

Can you post photos of your carport so we can get an idea of how the cats are accessing it?

I had in mind a a lattice of fishing lines sitting on top of the surface of your carport but you would need access to at least two sides to fasten it down.

The frame would be 4 pieces of timber with nails around the edges that the fishing line is wound around.

Since the cats can't easily see the fishing lines, when they try walking across your roof, they would find it an unpleasant enough experience they would hopefully move to another site to do their business.

However, a fence to stop them gaining access could be just as effective a deterrent!

Just make your frame a U shape with uprights that the fishing line can be woven between so that the cats can't perch on the top.

Cats can jump really high so broom handle height ought to do the job.

Any kind of net, stretched tight, three inches off the surface of the roof would, I think, make them much less happy to hang out there. Unless it was fine enough for them to hammock in.

I'm for the sprinkler system.
Getting hit with a sprinkler isn't like getting rained on.

When my indoor outdoor kitties decide it is time to abandon me, they look out the door, see it's raining, and choose the rain. These same idiots don't listen to me when I am setting up the sprinkler in the garden. They just laze about.... Until they here that line of water falling is coming closer. Oh shit! I'm gonna get wet! Cat out of hell speed occurs.

Christopher Weeks wrote:Any kind of net, stretched tight, three inches off the surface of the roof would, I think, make them much less happy to hang out there. Unless it was fine enough for them to hammock in.

I think this would work and not add much weight to the roof.
I often use a layer of woven wire fence, sometimes chicken wire, laid on the ground of a newly planted bed to keep cats from pooping there.  Kind of a pain but it does work...once plants are up they don't bother things...they would really hate the net a few inches off the ground.

so last night we got up to scare away one, this morning the dog scared away another. There are two turds up there though. Le sigh.
Good thing, they're not where I threw the detergent.

I'm feeling ill today (I swear I can still smell cat shit, and am trying not to think about all the ick that got on me yesterday). Taking a few days off from this, aside from dog attack, the husband is going to have to figure this out this weekend.

Cats really dislike being sprayed with water. A motion sensor water sprinkler did the trick for me to keep deer out of the garden (just have to remember to turn it off when you want to go there). a few nights in a row will send a clear message that the carport is not a good place for them to be.

I like the motion sensor water sprinkler suggestion.

Since the cats travel from roof to roof there might not be too much that can get them to avoid the carport until the sudden spraying of water.

I have read that a motion sensor sound device might also scare them away.

Those cats were probably taught by their mother to travel by roof and the mother was probably taught by her mother going back many generations.

I hope you will let us know what the solution turned out to be.

I did some looking and it looks like I can get one of these spray-sensor things from China for a few hundred bucks in maybe a few weeks (gulp).

I am thinking in the meantime I'm going to set a bunch of mousetraps up there. Once they start snapping that should be enough to get cats moving. Might be a one-trick thing but at least I can buy mousetraps anywhere.

Tereza Okava wrote: ... I am thinking in the meantime I'm going to set a bunch of mousetraps up there. Once they start snapping that should be enough to get cats moving. Might be a one-trick thing but at least I can buy mousetraps anywhere.

My friend used them around her Christmas tree to keep the cat off it! It was a domestic cat, rather than feral.

Unless the mousetraps are really cheap, I suggest attaching a string and tying it to something. If one gets caught in tail fur or a paw, the cat is likely to take it with them. Maybe a big piece of duct tape through a loop of string would be enough?

Ordering that could be best , yea.  But with these other friends online ready to help, many of them experts, why not build the same machine by hand?  Ummm,  it wont be impossible, because you have alert geniuses at hand , plus you are highly regarded here.  Permie SOS!
Maybe start with a lighted motion detection , open the back panel.  
Then wire in  a dependable connection that  sets off a wildly spraying circumference of water
And, to be  more offensive to the cats,  connect audio of vintage Black Sabbath or trained falcons as they hunt

Where are you , electricians?

Rico Loma wrote:... And, to be  more offensive to the cats,  connect audio of vintage Black Sabbath or trained falcons as they hunt...

What she needs is those actual birds of prey.

Many of us have heard of New York City's incredible rat problem that no human could fix...

Except some bright spark started putting nesting platforms on some of the skyscrapers. The targeted birds moved in, but also some sort of smaller predator - it may have been a variety of falcon, but please don't quote me as I'm not sure.

Either way, this aerial predator has been targeting rats, along with help from owls, and the rat population is taking a hit. Yeah wildlife helpers! All they needed were safe nesting sites, and they volunteered to do the dirty work.

Not sure Tereza has a good spot for a nest platform that wouldn't freak her dogs out?

Alas, I just paid a ridiculous amount to install this thing about 6 months ago!!! where's that crying emoji.... and it has a custom made steel structure that will be used even after we replace the roofing material in the future.

Do the cats poop on your neighbors roofs also or are they picking on your new roof til it smells just right?

We have TONS of birds of prey!! I often get visits by them when I'm out working in the garden (mourning doves like to sun themselves on my back garden wall, and I've had a hawk fly right past me to nail one). I leave some trees very tall in my yard for them and do everything I can to encourage their presence.
We have some nocturnal birds (nightjars) so maybe we have owls, but the ones I can set my clock by, a pair of carcarás (https://en.wikipedia.org/wiki/Crested_caracara ) come by every morning and every afternoon. They make their hunting call as they fly over and all the birds scatter. They do not, alas, hunt at night.

I talked to one neighbor yesterday, who said she hadn't noticed cats. But I did notice the lady on the other side has been washing her glass carport a lot more often. I'll see if I can catch her one of these days. The smell is probably affecting her even more than us, since her yard is higher and it just wafts right up there.

Jay, thanks a mil for the idea about connecting string to the traps, I never would have thought of that.

Two thoughts:

I wonder if a motion sensor under the roof could set off a loud stereo system aimed at the roof. Cats hate to be surprised.

A passive option is to strap a couple of layers of loose chicken wire across the roof, with some thin sticks between the layers. Makes a nasty place for cats to walk. You can always borrow and connect an electric fencer to the layers to break the behaviour.

Douglas Alpenstock wrote:Two thoughts:

I wonder if a motion sensor under the roof could set off a loud stereo system aimed at the roof. Cats hate to be surprised.

A passive option is to strap a couple of layers of loose chicken wire across the roof, with some thin sticks between the layers. Makes a nasty place for cats to walk. You can always borrow and connect an electric fencer to the layers to break the behaviour.

The chicken wire is a good idea. I have used it in the garden to keep out cats, I know they don't like walking on it. Not sure about the electric fence, as the rain is coming back tomorrow...

The stereo would be hysterical, but my bedroom is right there under the carport and my neighbors' bedroom is right next to where we would have to put the whole mess. The cats running up there wakes me up (I'm a light sleeper) but I try to respect the neighbors since we are in an urban setting.

The good news, there has been less. Where I threw the laundry soap, the cats have stayed away.
The bad news, I was down for the count yesterday with something that felt viral, like out of my head fever. Today I am feeling slightly more human (it's only 9AM, so that is to be determined) but I'm not doing anything else with this situation without a respirator.

Tereza Okava wrote:...but I'm not doing anything else with this situation without a respirator.

Yes!!! Yes to the power of 1 respirator that properly fits you! People have died from illnesses caused by breathing in bat guano, and I don't imagine cat poop is any safer.

Tereza Okava wrote:...birds of prey!!  

First, sorry you're going thru this - Sounds like a PITA.  Second, reading thru some of the (Excellent..) replies - This, above, was my first thought: Get a couple of solar-charged 'Robo-Owls', ie: https://www.amazon.com/dp/B0D5M7C1HZ - Which:

- Have motion-detection (and it Really works well - See 'backstory' below..)
- LED 'Retina-flash' eyes
- Dynamic head movement, and
- a Reeeealy annoying 'screech'.. They will Definitely freak a cat out (at least, initially..)  

I'd bet that a couple of them, placed on each 'Reachable' corner of your (which is, indeed, Huge!) Carport, there, each positioned so their motion sensor will cover a wide 'field' of the roof (so All 'entry points' are covered) could be an effective 'scare the bejeezuz out of them / re-education program' tactic.



We had a similar 'nuisance creature' issue in our back fenced 'Dog run' (keeps them close to the House at night - Better as 'alarm systems' / Not getting eaten by Coyotes with Morning Doves constantly using their Water Bowls as.. well.. 'Bird Baths / Toilets' Sure - When the Dogs are awake / attentive, well.. 'Dove snacks' are on the menu..

..But when they're napping - those Doves sneak in like little CIA-operatives and would absolutely Scuttle their water-bowls with bird-scootie - Not very refreshing for them (and, I was Certainly not going to 'electrify' their stainless water-bowls, Nor try and 'camp out' all bloody day to snipe them with a pellet gun, etc

So, Tried perching one of these 'Robo-Owls' up on a post, far corner of thier penned-area, and Voila - Birds come into 'sip' - and are promptly screeched out of the area (and, Overall, have noticed a 'Drop in drop-ins' - so, it Seems to be spooking them from afar, as purported.) 'Your Mileage May Vary' and all, but perhaps worth a shot? Certainly not "hundreds of dollars" / a Lot of effort to try.

Also, we used 3M's double-sided 'Outdoor Mounting Tape', ie:

..onto the base / post-top Block for it, and that has Held thru heat / rain, etc very well.

Aside from this, indeed, not being Able to 'get Up on it' limits Other viable options (ie: stretching / mounting 'surplus camo netting' across it all.. or, 'blanket' with spray-mount glued thumb-tacks, every square-inches' intersect..  quite a bit..  

..But, this 'Robo-Owl' idea only requires access to one / two Corners (or, maybe right Close to their 'poop-zone') sufficient enough to get good 'detector coverage' / Sunshine - and see what happens.  Just an idea.