How Rats Actually Get Into Your Roof
"There's no way in. The house is sealed."
This is a common thing I hear on rodent jobs, usually from someone standing next to the way in. No rat teleports into a roof void. Every single one took a route — a specific, findable, usually preventable route. After a few hundred roof inspections across the North East, it's nearly always the same short list.
The gap is smaller than you think
A rat gets through about 1.3cm gap. A mouse manages in around 7mm mark, a pencil width. Hold your fingers that far apart. That's the whole security breach. On North East Adelaide homes — mostly seventies and eighties brick — the usual offenders are eave and fascia gaps, unscreened roof vents, where the pipework and cables come through, lifted or cracked tiles, weep holes, and the space behind the gutter where the corrugated Colorbond gives way and the sheets meet the fascia.
None of it looks like a door. Unfortunately they're all a door, and rats love them — an enclosed opening means most of their predators can't follow.
The bridges
Being the little guy, rodents avoid the opening as much as they can. So rats prefer travelling with cover than crossing open ground. And they climb anything, once I saw one climbing a colorbond fence, with no grip whatsoever.
They are great jumpers too, so branches within about six feet of your roof are a road in. That's the clearance the University of California's pest program recommends, and it's about 1.8 metres — further than most people prune.
Dense plantings want about two feet of clear air between them and between them and your walls, so there's no continuous covered route across the yard.
Ivy, star jasmine and honeysuckle growing up walls and fences are the single most generous thing you can offer a roof rat. A ladder, with hiding places, attached to your
house.
Fences and power lines running to the roof do the same job, and they use it on a daily basis.
Do I need to cut down the fruit tree?
Short answer: no. But don't leave the fruit lying around either.
People offer this up all the time, usually apologetically, like they've been harbouring a fugitive. And I understand why — if you've seen a rat working through your figs or mandarins, it feels like the tree is the problem.
They absolutely do eat it. I've seen figs and mandarins stripped over and over, and roof rats will hollow out an orange and leave the empty skin hanging on the branch. Under pressure they'll go at almost anything sweet. What I don't see much of is lemons and limes — too sour, and not enough sugar, they want the sugar from sweet fruits.
Here's the thing though: taking the tree out doesn't fix it. University of Arizona researchers looked at this and found roof rat numbers aren't tied to the availability of food plants, because rats eat seeds, leaves, bark and roots too, and forage well past your fence into bins, dumpsters and the neighbour's yard. Fell your fig and they eat next door's, then come home to the same warm roof.
What actually helps:
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Pick the fruit as it ripens and clear what's fallen. Unharvested fruit sitting on the tree or rotting underneath is a standing invitation — and in an Adelaide summer, juicy fruit is a water source as much as a feed, which matters more than people realise when everything else is dry.
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Prune the branches back off the roofline. This is the one that counts. The tree isn't the problem; the tree touching your roof is.
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Keep the tree. Make lemonade. Or in this case, jam.
Getting in is one thing. Staying is another.
Once they're in, four things decide whether they move in permanently:
Water. Bigger draw than food, and the one people overlook. A dripping tap, a blocked
drain, a leaking gutter, the dog's water bowl.
Warmth. Which is why autumn and winter are the season, and why a roof void is five
stars.
Nesting material. Insulation, stored cardboard, old fabric. Your roof is a hardware shop.
Food. Pet food left out overnight, bins against the wall, chook feed, fruit left on the
ground.
Take away the water and the warmth is worth a lot less
A proper rodent treatment deals with both the colony and the entry points - Rodent Control
What I'm actually doing up there
The main target of an inspection inside roof void through the manhole is to find evidence of their presence, droppings, rub marks, gnaw marks. With that I not only narrow down if whether it's mice or rats, and from the evidence, roughly how many.
Main entry points are also flagged during that inspection, along with a look at the roofline from outside, entry point is almost never where the noise is.
Sound travels along beams; rats do not enter through your bedroom ceiling. Then you get photos of what I found and an explanation of which gaps matter and which are cosmetic.
In regards to proofing up, I offer the service so you can get the results on the spot, instead of finding someone else to do it. A few client want to do themselves but this is a tricky point and I don't recommend it, unfortunately Falls are Australia's leading cause of injury-related hospitalisations, and more than 6,000 Australians are hospitalised each year after falling from ladders - AIHW
It's not about skills at all, in fact this is not rocket science. In my opinion is more about being used to it. With practice you get better at it, but you also get way more aware of the dangerous involved, and having a ladder at hand is not a good reference to answer: Shall I do it my self or not. This is one that falls into: I can do it, instead is should I do it? I hope this makes sense.
If you're past the reading stage and want it dealt with, this is exactly what my rodent treatment covers — and the inspection's free."
Not sure? Send me a photo
Hearing something up there and want to know how it got in? Call or text me on +61 457 601 995. Free initial inspection across North East Adelaide.
Werner — House Care Pest Control Local, family-safe, prevention-first