On the 18th August, 2019, there was a huge hailstorm in Adelaide and it accumulated in the area where the back extension meets the original house. (I remember the date as it was the day I returned from volunteering as a teacher in summer school in Hong Kong.) As the hail melted the water ran into the extension. It ruined my computer and printer and, over night, a portion of the ceiling collapsed. I thought I would be covered by my insurance but the claim was refused. They gave reasons but the interesting point is that no matter how much rain we have had since the roof has not leaked again. (I'm saving up to get the ceiling fixed!)