Most blocked gutters are cleared badly rather than left alone. The leaves come out, the run looks clean from the ground, and it overflows again in the next heavy rain — because what was blocking it was never the leaves. It was the silt sitting in the outlet underneath them.
This is the sequence that avoids that, and the checks that tell you whether it worked.
What actually blocks a gutter
Four different things, and they need different handling — which is why a single pass with a scoop so often fails:
- Leaf litter. Bulky, obvious, and the easiest to remove. On the older Dublin roads — Rathmines, Drumcondra, Clontarf, anywhere with mature limes or planes along the footpath — this arrives all at once in November, and it is what most people picture when they think of a blocked gutter.
- Roof grit and shed moss. Continuous rather than seasonal. A concrete tile sheds sand throughout its life and a mossy roof sheds all year, so this is the material that silts a run rather than plugging it.
- Compacted silt in the outlet and hopper. The actual blockage in most cases. It sits below the debris line, it is heavier than it looks, and water alone will not shift it once it has set.
- Nesting material. Common behind the fascia and in the tops of downpipes. Nesting birds are legally protected here during the breeding season, so this is a job with a season attached rather than one to force.
The order to work in
Downhill last, and never flush first. That is the whole principle. Water introduced before the outlet is clear carries silt straight into the outlet and packs it, turning a ten-minute job into a rodding job.
- Lift the bulk out dry. Scoop by hand into a bucket rather than dropping it — wet leaf litter stains paving and render, and cleaning the path afterwards takes longer than bagging it did.
- Clear the outlet before anything else. The hole at the end of the run where it drops into the downpipe. Get a hand or a trowel into it and take the compacted material out rather than pushing it down.
- Clear the hopper, the funnel at the top of the downpipe where one is fitted. The second most common blockage point, and the one most often skipped because it looks clear from above.
- Check the downpipe runs. Tap down its length: a dull note means it is holding material. A blocked pipe needs rodding from the bottom, not the top, and is a different job from a blocked gutter.
- Flush the run last, from the far end towards the outlet, and watch where the water actually goes.
Proving the run is actually clear
This is what separates a gutter that has been cleaned from one that has been tidied, and it takes about two minutes:
- Water in at the highest point should reach the gully within seconds. A delay means it is pooling somewhere along the run.
- Nothing should stand in the gutter once the water stops. A standing puddle is a fall problem, not a debris problem.
- Listen at the downpipe. A clear pipe makes a continuous sound; an intermittent gurgle means a partial blockage further down.
- Check the gully at the bottom. A downpipe discharging into a blocked gully backs up and overflows at ground level, which looks like a gutter fault and is not one.
On our own work the run is filmed on a pole camera before and after for exactly this reason. A gutter is the one part of a house its owner cannot inspect, so being shown inside it is most of what you are paying for.
When it is a repair, not a clean
Some of what presents as a blockage will not be fixed by clearing anything, and these are worth recognising before spending money on the wrong job:
- Standing water in a clear run means the fall is wrong. Usually a bracket has dropped, or the run has been distorted — very often by a ladder leaned against it.
- Water tracking behind the gutter onto the fascia. Either the gutter has pulled off the board or the roof felt has failed at the eaves. Act on this one quickly, because it wets timber rather than masonry.
- Weeping joints on uPVC. The seals harden and stop sealing. A clean will not restore them.
- Rust and pinholes in cast iron. Common across the Victorian and Edwardian stock of inner Dublin, where original cast-iron gutters and downpipes are still in service. Usually worth repairing rather than replacing — but it is repair work.
- Box, parapet and valley gutters. Internal runs on terraces overflow into the building rather than off the side of it, so the consequence of getting it wrong is much larger. They are also where a blockage is most likely to be a lead or felt failure rather than debris.
Doing it safely, and where the limit is
On a single-storey extension or a garage, with a stable ladder on firm level ground and somebody else in the house, this is a reasonable job to take on yourself.
At two storeys the calculation changes, and the risk is not only the fall. A ladder leaned against a plastic gutter distorts the run and costs it the fall that stops it silting — so the ladder used to clear the blockage is a fair bet to cause the next one. Ladder feet on a flowerbed, a sloped path or a conservatory roof create their own problems.
Ground-based vacuum systems reach a normal two-storey roofline without anything touching the gutter, which is why this work has largely moved off ladders. If the roof above is carrying moss, do the roof first — clearing a gutter under a mossy roof treats the symptom, and the run silts up again within the year. How often the whole job needs repeating is covered in how often gutters need clearing in Ireland.