Where new gutters come up
Extensions are the most common. The new roof has to drain somewhere, and tying it into the existing gutters is where trouble starts if the old system was already working at its limit.
Sheds, garages, carports and patio roofs come next. A big shed roof drops a lot of water along one edge, and without gutters it ends up against a fence, a neighbour's wall or your own slab.
What to decide before anyone quotes
Where the water ends up
Rules about where roof water can discharge differ between councils and states, so ask whether it'll go to the stormwater drain, a tank or both. In Victoria, that connection is regulated roof plumbing work. If it feeds a drinking water tank, the NCC (the national building code) says gutters, downpipes and flashings must not contain lead.
How big the gutter is
The NCC sizes eaves gutters for a short, intense burst of rain at your location, with overflow measures for rarer, heavier storms. Match the shape to the house, or read about quad and half-round gutters if you're choosing.
How many downpipes, and where
Under the NCC, one downpipe can drain no more than 12 m of gutter, and downpipes belong as close as possible to any valley. Put them where water can get away easily, not where they're easiest to hide.
Leaf guard from day one
If trees overhang the new roof, having gutter guard fitted during installation saves a second visit later.
How a good installation goes
The installer sets out the fall first, usually with a string line. The NCC asks for at least 1:500, with brackets at every stop end and corner and no further apart than 1.2 m. The gutter is then fixed, joined and fitted with stop ends, outlets and downpipes.
BlueScope's guidance for its steel gutters adds the details that separate a tidy job from a short-lived one: enough fall that water doesn't pond, joints lapped and sealed with neutral cure sealant, metal filings swept out, and air conditioner drains piped to the ground rather than into the gutter.
On an extension, the join between old and new gutters needs care, and the existing downpipes may need upgrading to handle the extra roof.
Questions to ask the installer
- Are you licensed for roof plumbing and stormwater work in this state?
- How did you size the gutter and decide how many downpipes it needs?
- Where will the water go, and is that allowed here?
- What overflow measure are you using, and where will overflow spill?
- Will joints be sealed with neutral cure sealant, and filings cleaned out before you leave?
- What warranty do you give on the workmanship?
Your part, and the installer's
You can
- Decide where you'd like downpipes and any tank before the installer visits
- Ask your council about drainage rules for a new shed or extension
- Note which trees will drop leaves on the new roof
Leave to a roofer
- Setting out the fall and fixing brackets
- Connections to the stormwater system
- Joining new gutters into an existing system
- Any work above a single storey
Our advice
Sort out where the water goes before you talk about colours. Ask each installer to sketch where the downpipes will sit and where they drain. If you're adding an extension, we'd also have them check the existing gutters and downpipes, because an old system that already struggles will struggle more with extra roof feeding it.
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.