Hiring a Gutter Installer is buying the right size — and most gutters are sized for half the rain.

Gutter replacement is priced per linear metre, fitted — but the quoted rate is only half the story. The bigger cost lines (downpipes, brackets, fascia repair, scaffold for two-storey) are often buried in "supply & install" without itemisation. Get the breakdown.

Three questions to ask

1. →Is the gutter Quad, Half Round, or Box? Box (rectangular) carries more water than Quad of the same width — sometimes 40% more. If you've had overflow, ask about a box upgrade.
2. →Are downpipes priced per unit and where do they discharge? Stormwater connection is regulated. "Discharges at ground level" is not legal in most councils — it must connect to the legal point of discharge.
3. →Is fascia included if rotten, or extra? Buyers report being told "fascia looks fine" at quote, then $1,400 added on the day. Get it inspected up close before signing.

The guy was a general plumber. Said gutters were no problem. Two weeks later the joins were leaking everywhere. Found out he wasn't licensed for roof work at all.

Guttering is a specialty under the plumbing trade — the licence class is "roof plumber" (sometimes called "roofing — roof drainage" or similar in your state). A standard plumber's licence does not cover it. This catches more buyers out than any other vetting failure in the trade.

The five-minute check

1. 1. Get the licence number. Check it on your state register (Building Commission NSW, QBCC, BPC). Confirm it covers roof plumbing, not just general plumbing.
2. 2. Ask if they're a BlueScope-accredited installer. If they install Colorbond, this is how the 15-year warranty is honoured.
3. 3. Request three recent jobs — preferably with photos showing downpipe discharge and bracket spacing.
4. 4. Confirm public liability insurance & workers comp current.
5. 5. Search ABN on ASIC + state register for any cancelled licences.

Every state of Australia regulates roof plumbing as a separate sub-class within plumbing. The work is hazardous (working at height), structural (load on fascia), and connected to stormwater (council-regulated). A general plumber doing it without endorsement is an offence — and your insurance will not cover the work.

What's at stake

If unlicensed work fails — water damage to ceiling, mould, electrical damage — your home insurance can deny the claim. Australian home insurance policies routinely exclude consequential damage from unlicensed trade work. The cost of getting this right is small. The cost of getting it wrong is the ceiling.

The honest answer is uncomfortable for the trade: most "gutters need replacing" calls are actually fall problems or blockage problems. A camera in the gutter and a spirit level on the lip will tell you in 20 minutes whether you have a $400 repair or a $6,000 replacement.

Most of what makes a gutter last 30 years vs 8 years happens in the two days of install. Bracket spacing, fall, joining method, downpipe connection, fascia treatment. None of it is visible from the ground once the trade leaves.

The seven specifications that matter

1. 1
   Bracket spacing. Maximum 1.2m centres for Colorbond Quad. Closer in snow or cyclone zones (600–900mm).
2. 2
   Fall. Minimum 1:500 (2mm per metre) towards the downpipe. Measured with a level, not eyeballed.
3. 3
   Joins. Lapped 20mm minimum, riveted, then sealed with neutral cure silicone — not acetic. Acetic eats Colorbond paint.
4. 4
   Downpipe positioning. One downpipe per 12m of gutter is the maximum span. More frequent in high-rainfall zones.
5. 5
   Stormwater connection. Hard-piped to the legal point of discharge. Not over a garden, not onto a path.
6. 6
   Fascia condition. Treated, painted, and structurally sound before gutter brackets go on. New gutter on rotten fascia is a year-one failure.
7. 7
   Roof flashing. Drip edge or anti-ponding strip ensures water enters the gutter, not behind it.

Australia's gutter market is dominated by BlueScope steel products. Colorbond is pre-painted; Zincalume is unpainted aluminium-zinc-coated steel. Aluminium gutter exists as a third option (mainly Stratco's range). The decision involves more than colour.

Coastal homes (within 1km of breaking surf) should specify Colorbond Ultra or aluminium. Standard Colorbond is not warranted within 100m of breaking surf and degrades inside the 100m–1km zone.

BlueScope's Colorbond paint warranty is one of the most generous in any building product category. It's also one of the most carefully written. The warranty doesn't cover rust through — it covers paint failure (chalking, peeling, flaking). And it has nine voiding conditions most buyers never read.

What voids the warranty

• ·Installation within 100m of breaking surf — unless Colorbond Ultra grade specified.
• ·Acetic-cure silicone sealant. Common DIY sealant. Reacts with the paint.
• ·Direct contact with copper, lead, or pressure-treated timber. Galvanic reaction destroys the paint.
• ·Industrial fall-out — near smelters, certain processing plants.
• ·Failure to clean as specified. Coastal homes require quarterly washing.
• ·Mechanical damage from ladder use. Scratched paint is excluded.
• ·Bird droppings allowed to dry. Acid etches the paint — permanently.
• ·Foliage contact. Branches touching gutter retain moisture against the surface.
• ·Pooling water from blocked downpipes. Standing water voids paint warranty.

BlueScope provides the warranty paperwork directly. Your installer should be able to produce it. If they can't, the warranty isn't being registered — meaning you have nothing in 12 years when paint starts failing.

Guttering specification is dictated by where the house is. A spec that's overkill in inner-Sydney may be inadequate 200km north on the coast.

Every gutter on every house in Australia is supposed to be sized to its roof catchment. The calculation is set out in AS/NZS 3500.3. Most installers do it. Some don't — and that's where the “the rain was too heavy” conversation comes from.

Ask your installer to show you the sizing calc. If they don't have one, they sized it from memory — and the memory was probably from a house in a different climate zone.

A Colorbond gutter installed correctly should last 30 years. The two things that shorten that life are debris (causing pooling) and direct contact with materials that react with the paint. Both are solvable.

Cleaning schedule

• · Twice a year minimum — end of autumn (leaves), end of spring (blossom + pollen).
• · Quarterly for coastal homes — required to maintain warranty.
• · After every major storm — check downpipes haven't blocked with debris.

Gutter guards — the honest verdict

Quality aluminium mesh (Leafgutter, GutterGuard) genuinely reduces cleaning to once a year and provides ember protection in bushfire zones. Cheap plastic mesh doesn't work, blocks, and degrades in UV within 5 years. The price difference matters: $25/m vs $80/m installed.

If your home is BAL-rated, gutter guards are no longer optional — they're part of compliance. Specify ember-rated mesh, not generic.