Nobody enjoys this question because the honest answer is not a single number. What matters is what is above the roof and what shape the roof itself is, and those vary enormously street to street across the Inner West.
What actually sets the interval
- Tree cover directly over the roof. A bungalow under a mature canopy fills faster than a terrace with an open sky above it, regardless of what the neighbours do.
- Species. Evergreens shed year-round, so there is no quiet season to skip. Deciduous street trees concentrate the load into a few weeks in autumn.
- Roof geometry. Every valley is a collection point. A roof with several valleys or a box gutter behind a parapet traps debris in places a gutter run would have carried away.
- Pitch. A low-pitch roof moves debris off slowly, so it sits and holds moisture rather than washing clear.
If you can only do it once a year, do it in late autumn after the leaf drop. That is the load that sits wet through winter, and wet debris against steel is what actually destroys guttering.
What a blocked gutter does to a roof
The obvious failure is overflow down the wall, which is annoying but visible and therefore usually gets dealt with. The expensive failures are the quiet ones. Water backing up in a gutter rises above the fascia line and runs behind it, into the eaves and the roof space, which wets timber that was never meant to be wet. In a valley, trapped litter holds moisture against the iron continuously, and a valley that would otherwise last decades rusts through in a fraction of that.
Box gutters behind parapets are the worst case and the most common in the terrace and warehouse-conversion stock through Glebe, Redfern, Surry Hills and Alexandria. They drain inward through a sump, and there is no overflow path except into the building, so a blockage stops being a maintenance issue and becomes an interior flood in a single storm.
Is gutter guard worth it?
It genuinely reduces how often you need to get up there, and on a bush-interface property it does a second job by keeping embers out of the gutter. It does not eliminate the task. Fine material still gets through and builds a silt layer underneath, and a guard installed over a gutter that already has a fall problem just makes the fall problem harder to see. It is worth doing on a sound gutter and worth deferring on a tired one.
When cleaning is no longer the answer
If a gutter is holding water after it has been cleared, the fall is wrong or the brackets have dropped, and clearing it again next season changes nothing. If there are rust perforations along the back seam, or the fascia behind it is soft, the gutter has failed and replacement is the cheaper decision. Both are visible in a few minutes on a ladder.
