What Canberra throws at roof drainage
Hail that fills gutters
The supercell of 27 February 2007 left hail 20 cm deep in the city centre, with drifts a metre high in Civic. When hail packs gutters and valleys, the rain behind it has nowhere to go but over the edge or back under the roof.
Storms from October to April
Most of Canberra's thunderstorms fall between October and April, and November averages the most rain at the airport. That's the season gutters, downpipes and outlets need to be clear and correctly sized.
A reminder of what blockages do
On 26 January 1971, culverts on the Woden Valley freeway blocked with debris and a flash flood killed seven people. Street drainage isn't roof plumbing, but the lesson carries over: a blocked outlet turns ordinary storm water into damage.
Things on the roof that drain onto it
Braddon's heritage rules name solar hot water heaters and air-conditioners among the things a roof may carry, and ask that they sit out of street view. Wherever yours are, BlueScope says copper-rich overflow from hot water systems corrodes coated steel, and air-conditioner condensate should be piped to the ground, not into gutters.
Who does roof plumbing in the ACT
This is where the ACT differs. Its plumber licences cover sanitary and water supply plumbing, and ACT Planning says not every professional on a home project needs a licence, listing roofing contractors among them. So a gutter installer may not hold any licence at all.
That makes other checks matter more. Access Canberra suggests asking for a certificate of currency for public liability insurance and recording the business name, address and ABN before signing. If the job is part of a full re-roof, that needs building approval and a licensed builder. Where a trade is licensed, its advertising must show the licence number.
What good roof plumbing includes
- Gutters with a fall of at least 1:500, brackets no more than 1.2 m apart, and an overflow path, as the NCC requires
- Enough downpipes, with each one serving no more than 12 m of gutter and sitting as close as possible to valleys
- Colorbond or Zincalume gutters under a steel or glazed terracotta roof, since BlueScope warns galvanised gutters corrode early there
- No copper, lead or stainless steel fixings or flashings touching coated steel
- Joints sealed with neutral cure sealant and metal filings swept off before the roofer leaves
Old gutters and downpipes can be asbestos
ASSEA lists asbestos cement gutters and downpipes among roofing products, and any Canberra home built before 1990 may have them. In the ACT only a licensed removalist may take asbestos out of a home. Don't cut, drill or break old grey gutters or pipes until they've been tested.
Before a Canberra roof plumber starts
- Can I see your public liability certificate of currency and ABN?
- Are my gutters and downpipes sized for a heavy summer storm, and where will overflow go?
- What will you do about the hot water overflow and air-conditioner drain?
- Are any of my existing gutters or pipes asbestos cement?
- What warranty do you give on the work and the materials?
What we'd do
We'd get the gutters, valleys and outlets cleared and checked in September or October, before thunderstorm season, and fix any downpipe that can't keep up. With no licence to lean on for most of this work in the ACT, we'd insist on insurance and a written quote. The national roof plumbing page explains each part, and the Canberra hub covers local rules.
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.