Mosman gutters deal with bark as much as leaves. Angophoras and blue gums shed long ribbons that bridge across a gutter and trap everything behind them, and on the stepped, multi-level homes common here that blockage is often three storeys up and directly above a paved terrace.

The debris in a Mosman gutter is coarser than most of Sydney. Angophora and eucalypt bark comes off in long strips rather than breaking down, and it lodges across the gutter to form a dam that holds leaf, twig and seed capsule behind it. Figs add a heavy, waxy leaf that rots slowly and packs tight.
The Federation housing stock complicates it further. Box gutters and internal valleys are common on homes of that era, and unlike a simple eaves gutter they drain to a single outlet. One blockage there does not overflow harmlessly over the edge, it backs up under the tiles and into the roof cavity, which is how a gutter problem becomes a ceiling problem.
Topography is the third issue. Mosman falls steeply toward the harbour, so houses step down their blocks and the gutter you need to reach is frequently well above ground on the downhill side, over a terrace, pool or retaining wall where a ladder cannot be safely footed.
Vacuum clearing handles the reach from the ground and pulls the packed bark out rather than pushing it toward the downpipe. We check the box gutters and valley outlets specifically, because those are the ones that actually cause damage here.
In most suburbs a blocked gutter overflows and you notice. In Mosman, on a Federation home with box gutters and internal valleys, it frequently does not overflow at all — it backs up under the tiles.
That is the whole argument. Water entering a roof cavity does its damage out of sight, in the ceiling framing and insulation, and the first symptom is usually a stain appearing on a ceiling well after the leak began. On a heritage property with lath and plaster or ornate cornice, that repair is specialist work and priced accordingly.
There is a second cost specific to the housing here. Original valley irons and box gutter linings on homes of this age are often near the end of their service life already. Sitting them under a permanent load of wet bark and leaf accelerates corrosion, and replacing a lined box gutter on a heritage roof is roofing work, not maintenance.
Regular clearing also means someone is looking at those valleys and outlets on a schedule, so a failing lining is found while it is still one section rather than the whole run.
How vacuum gutter clearing works, what we check while we are there, and what it costs across Sydney.