Dexter Cairns 
A Northcote homeowner had a brushtail in the roof and couldn't work out where it was getting in. It was coming off the box gutter, ducking under a spot where the flashing had lifted from the parapet. The fix was a one-way door, then re-dressing and sealing that junction so it's weatherproof and she can't get back.
What he had
Got a call out to Northcote, bloke with a possum in the roof. Doing his head in. He’d already had a couple of people out who poked some mesh in here and there. Possum was still getting in. Still thumping about over the bedroom, every night, and he was about ready to give up.
Where she was getting in
First thing I do is get up top and look at where the water goes. That tells you most of the story. This one had a box gutter running behind the parapet, classic inner-north terrace, and the flashing down one side had lifted. Not by much. You’d never pick it from the yard.
She was walking that gutter at night and ducking in under the lifted flashing. Like a little door someone left open for her. Guttering’s where I came from before this, so that’s the first place I look on the old places. Flashing lifts, capping cracks, water gets under, and that’s your way in. Nine times out of ten. People miss it because they’re staring at the tiles.
What we did
One-way door first. She gets out, can’t get back. We don’t trap, don’t cart her off somewhere. Poor thing was just after somewhere dry.
Then the actual job, which is the gutter line. Dressed the flashing back down, sealed it properly, mesh into the gap. While I was up there I went along the rest of the capping and re-bedded a soft spot near the downpipe. Sort it now or it’s the next way in by winter.
The bit that matters
Mesh on its own doesn’t fix this. If the flashing’s lifted and water’s getting under, the gap opens up again and you’re back where you started. Sort the guttering, seal it for the weather, and there’s no way back in. She was fine, by the way. Bit grumpy at being moved on, but fine.
