Napalm is right out.

January 13, 2009 10:43 PM

What do I do about the rats living in my roof? Without leaving decomposing rat corpses above my ceiling?

There's a gap between the roof of my house and the joists and ceiling below it. Since we live in the Pacific NorthWet, I assume that this is to mitigate moisture/mold issues.

But, some rats have chewed through the mesh that covers the gap. And now a whole family of them lives in there, scurrying around and keeping us awake at night. They feed off of my compost heap, but even when there's no food available they still use my house as a home base.

I want them gone. But, I don't want any corpses rotting up there. This rules out poison, as I'd have no control of where they died. The space is too small to put my cats up there. I've considered building an armed robot, but I suspect that the joists will render a wheeled vehicle useless. If I just block off the hole, I'm certain to be trapping live rats inside who will either a) die of starvation and rot; or b) chew another hole elsewhere to escape.

At this point, the best plan I've come up with is to fill my paintball gun with hard rubber riot control balls and lay in wait for them to either emerge or attempt to enter. In the times when I sleep, I would block up the hole. (Mind you, I know that air rifle pellets would be more humane, but I don't want a zillion little holes in my eaves.)

I suppose non-lethal measures would be acceptable. But, my primate territorialism is demanding rat blood.

posted by Netzapper to home & garden (16 comments total)

Rat traps. Buy those with a yellow plastic trigger that's embedded with a chocolate scent, so you never need to bait them. You can tape or tie them to a long stick if you want to set them farther in than you can reach.
posted by weapons-grade pandemonium at 10:54 PM on January 13

The gap between the lower level and the roof is only about two inches. I don't think a rat trap is going to have enough room to operate. But, I'll have to check the hardware store.
posted by Netzapper at 10:58 PM on January 13

Well, have you tried talking to an exterminator? Not to sound snarky, but it is their job and I'm sure you're not the first person to have this situation....

I have a similar problem with squirrels, and although the space in the roof is much bigger, big enough for a person to fit, I also couldn't imagine what could be done that wouldn't result in dying squirrels stuck in the roof space, but the exterminator figured it out -- they'll put in traps, and as part of the price, they come back every single day and check the trap for caught/dead squirrels. Once they're sure that the nest is empty (using whatever knowledge they have of rodent habits; again, their job) they plug the hole, and continue to come back and check every couple of months or so.

Your situation would probably be different since the space is so small, but you can certainly get a free quote/consultation from an exterminator or two, and see if you can do what they were going to have done yourself.
posted by thebazilist at 10:59 PM on January 13

I feel your pain. Been there, smelled that.

The best and only option is exclusion. You must keep them out. If you really think that their port of entry serves a purpose (and I think you should get a second opinion on that), you need to do your best to close it off in a way that still allows airflow. Whatever mesh was there previously was obviously useless. Use 1/4" hardware cloth to screen off all the openings. They can't chew through it. Attach the hardware cloth to whatever surrounds the openings with screws and washers.

Don't use bait/poison. Like you fear, they'll die in your walls and stink up the place. Use snap traps if exclusion isn't going to totally solve the problem.

If that happens, though, consider investing in an Earth Care odor remover bag. When a rat died in my crawlspace last year, it really helped.
posted by mudpuppie at 11:00 PM on January 13

On preview:

As for any knee-jerk responses that amount to "Call an exterminator, jackass!" -- I learned the hard way that, at least in my part of CA, exterminators simply will not climb an exterior ladder, even when that's the only way to deal with a pest problem. They're not insured for it, and they won't do it.

Either that, or they all hate me and agreed to use that as their excuse.
posted by mudpuppie at 11:03 PM on January 13

You could also try this bobcat urine stuff. Most rodents have a built-in fear of the smell of the urine of predators. Perhaps put it around the compost pile and somehow get it into the attic? It won't smell strongly enough to smell for you but they'll smell it and perhaps get anxious enough to think their nest isn't as secure anymore (in addition to all the other things that you try to get rid of them)
posted by lockle at 11:42 PM on January 13

Also been there, done that (or at least my in-laws have in their holiday house). We placed rat poison in the roof cavity and sealed up all but one exit, which led outside the roofspace and house. Rat poison can be bought (here in NZ, at least) at farm-supply stores, and it works by making the rats so thirsty that they seek out water and drink until they drown. If you leave them an exit, they'll remove themselves for you and die elsewhere.

What you want is rat bait containing Brodifacoum.
posted by tracicle at 11:52 PM on January 13

I've heard stories, but haven't tried myself, of strobe lights being very effective for removing attic pests. Googling this seems to result in a glut of such products, indicating that other people believe this to be true as well. However, they seem expensive, and do not satisfy the condition of extracting rat blood, as it merely drives them out of the attic to live somewhere else.

If you can somehow observe what routes they regularly take into and out of the roof, and place traps along that route, rather than right at the entry space, it would probably work. Though if you've got families up there, you still run the risk of killing a momma rat and her babies rotting and stinking up the place.
posted by po at 12:44 AM on January 14

In a vein similar to the strobe lights mentioned above, around here you can get a small ultrasound generator that works pretty well for rats and the like. The catch is that they get used to it, and eventually come back, but you should have the entryway patched by then.

If you do find one, check that it's ok to use with any pets in or around your house.
posted by ghost of a past number at 4:43 AM on January 14

A previous MeFi post about mice might help you... especially my advice about laundry detergent and peanut butter; a tried and true method I have personally used with rats.
posted by teabag at 5:17 AM on January 14

We had squirrels in our attic, and we eventually had to call an exterminator to get rid of them. As thebazilist said, this is what they do. In our case, they put a metal band around the roof line to keep the little furry tailed rats out, and then set traps that they checked every two days for the next week so that they were sure that all the little vermin were gone.

You do need to get this taken care of. The rodent proofing was moderately expensive, but the cost to repair the damage done by the squirrels chewing on the wiring in the attic was very expensive, and the damage they caused to the wiring could have easily burned our house down. Had we taken care of the problem sooner, the costs and potential danger would have been much lower.
posted by ralan at 5:48 AM on January 14

Not to gross you out, but there are always decomposing rat corpses in your house. It's not like the little beggars self-immolate, after all.

Lure them outside with something (food works better than a flute) and then fix the hole.
posted by rokusan at 6:27 AM on January 14

Not to gross you out, but there are always decomposing rat corpses in your house.

I doubt it- decomposition smells really bad.

Re: rat poison. The "makes them seek water" stuff is just warfarin. And I have heard that the "seeking water" thing is a myth to reassure people that rats aren't dying in their attics. I don't know where rats go to die, but I suspect they don't care too much.

Traps are the answer- you have to eradicate the population of rats that think your house is their house. You might scare them out and seal up the walls, but they'll be back and eat through the seals pretty quickly. The problem won't be solved until the rats that know about your house are gone. It's up to you how to effect this eradication.
posted by gjc at 7:53 AM on January 14

For a start, eliminate food sources. That means your compost heap, among other things, at least until you have the bastard vermin under control. Also any birdseed, unharvested fruit or vegies (we had trouble with grapes).

Then you trap the he'll out of them around your house. Look into enclosed traps. Be prepared for some collateral damage. We used classic open traps and ended up with a dead wren and a stunned squirrel.
posted by Good Brain at 8:18 AM on January 14

Not to gross you out, but there are always decomposing rat corpses in your house... I doubt it- decomposition smells really bad.

If the carcass is open to flies, then it will be nothing but a fur flecked stain in short order.
posted by StickyCarpet at 8:30 AM on January 14

If the carcass is open to flies, then it will be nothing but a fur flecked stain in short order.
Posted by StickyCarpet

Eponyvolting.
posted by lostburner at 10:52 AM on January 14