What kind of gutter leak is it?
| Probable cause | Usual fix | |
|---|---|---|
| A steady drip from one spot, under a joint or corner | Failed sealant or rivets at a join | Joint cleaned, re-riveted and resealed |
| Drips along a stretch, with rusty stains below | Rust holes in the base of the gutter | That length replaced, or the whole run if rust is widespread |
| Water pouring over the front in heavy rain | A blocked gutter or downpipe, or a gutter too small for the roof | Cleared first, then extra downpipes or a bigger gutter if it still overflows |
| Water running down the fascia or wall behind the gutter | Overflow going backwards, or tiles stopping short of the gutter | The overflow path or the gutter's position fixed, or the roof edge extended |
| Water still sitting in the gutter days after rain | Not enough fall, or sagging brackets | The gutter re-hung with proper fall and bracket spacing |
| A downpipe leaking at its joints or gushing at the bottom | A blockage lower down, or a failed joint | Blockage cleared, joint resealed or that length replaced |
How a gutter is supposed to work
For new work, the NCC sets out the basics: a fall of at least 1:500 so water runs to the outlet, brackets no more than 1.2 m apart, and an overflow path that sends excess water outside the house. It also says one downpipe can serve no more than 12 m of gutter.
Existing homes don't have to meet the current code unless new building work is done, so many older gutters are flatter, longer between downpipes or smaller than they'd be built today. If yours overflow when they're clean, that's often the reason.
At the roof edge, the NCC requires tiles to overhang into the gutter by at least 35 mm. Where they stop short, water can run down the back of the gutter and behind the fascia, which looks like a gutter leak but starts at the roof.
Why gutters rust before their time
Mixed metals. BlueScope says galvanised (zinc-coated) gutters can corrode early under Colorbond or Zincalume roofs and glazed terracotta tiles, and that lead, copper and stainless steel must not be used with its gutters. A copper pipe or old lead flashing draining into a steel gutter eats it from the inside.
Water that sits. A gutter without enough fall holds puddles and leaf sludge, and the base rusts first.
Air conditioner drains. BlueScope says condensate from air conditioners should go to the ground, not into gutters.
Leftover filings. Metal filings left in a gutter after cutting or drilling rust where they lie.
Age. The NSW Government's heritage schedule gives steel gutters a life expectancy of 10 years and more, against 70 years and more for copper or stainless steel. An old steel gutter rusting in several places may simply be done.
Ladders, power lines and old gutters
A ladder is for looking into the gutter, not leaning out to work. Only use one on firm, level ground on a single-storey house, with someone holding the base, and only if you're comfortable up there. Keep well clear of the power line running to the house, and never step from the ladder onto the roof. If the house was built before 1990, the gutters or downpipes could be asbestos cement, and gutters under an asbestos roof will likely hold asbestos debris. Don't scrape, cut or water-blast them.
How to work out what's wrong from the ground
Wait for steady rain
Walk around the house under an umbrella or watch from windows. Note every spot where water drips, sheets over or runs down the wall.
Mark the drip spots
A bit of chalk on the path under each drip makes it easy to show the roofer later, once everything's dry.
Check each downpipe at the bottom
If one is dry or barely trickling while the gutter above overflows, it's blocked. Clear the outlet if it's at ground level and you can reach it by hand.
Look at the fascia and eaves after rain
Dark streaks, peeling paint or soft timber behind the gutter mean water has been getting in behind it for a while.
Look into the gutter on a dry day
If you're comfortable on a ladder and the house is single storey, check for standing water, rust holes, sagging brackets and failed joints. Take photos rather than poking at it.
Send the photos to a roofer or roof plumber
Point out the chalk marks and any downpipe that wasn't flowing. They'll know quickly whether it's a reseal, a re-hang or new gutters.
Your part, and the roofer's
You can
- Watching where it leaks during steady rain
- Clearing a downpipe outlet at ground level
- Looking into the gutter from a ladder on a single-storey house, if you're comfortable
- Keeping branches trimmed back from the gutter line where you can reach from the ground
Leave to a roofer
- Resealing and re-riveting joints
- Replacing rusted lengths or whole runs
- Re-hanging gutters to fix the fall
- Adding downpipes or overflow slots
- Any gutters or downpipes that might be asbestos cement
What we'd do with a leaking gutter
One leaking joint, we'd get resealed and move on. Rust in a few places along an old steel gutter, we'd price a new run rather than paying for patches every winter. And if clean gutters still overflow, we'd ask about an extra downpipe before anything else, because it's often the cheapest way to get more water off the roof.
Want a roofer to take a look?
Tell us the job and your postcode. We match it with a Find My Roofer certified roofer who specialises in that kind of work, and they call you to quote. Your number goes to them alone.