Why Melbourne keeps roof plumbers busy
Terraces drain through hidden gutters
Rows of terraces from the 1850s to the 1890s fill suburbs like Carlton, Fitzroy, Collingwood, South Melbourne, Port Melbourne and Richmond, and their designers hid the roof behind a decorative parapet. Water off those roofs runs into box gutters and out through rainwater heads you can barely see from the street. When one blocks, the overflow often ends up inside.
Big roofs fail when the water can't get away
In the March 2010 storm, roofs failed at Southern Cross station and Docklands Stadium, and overloaded guttering was the main reason homes across the city were damaged. Melbourne doesn't get huge yearly rainfall, so gutters and outlets can sit half blocked for months before a summer storm finds them out.
Old metal, new metal, and what touches it
Older roofs may still have lead flashings, and copper-rich water from a hot water unit's overflow can end up on the roof. BlueScope says both corrode Colorbond and ZINCALUME steel, so old lead flashings need painting or separating, and overflow pipes should run past the roof, ideally to the ground.
What a roof plumber looks at
Box gutters and their outlets, sumps and rainwater heads come first on a parapet roof. The National Construction Code lets box gutters be designed to AS/NZS 3500.3 for size, fall and overflow, so a roof plumber can tell you whether yours was ever sized properly.
On a pitched roof, they'll check that downpipes sit close to valley gutters and that none serves more than the 12 m of gutter the code allows. They'll look at flashings around chimneys, walls and skylights, and at where air conditioners drain. BlueScope says condensate should be piped to the ground, not into the gutter.
Questions for a Melbourne roof plumber
- Are you licensed for roofing (stormwater) work, or registered and supervised by someone who is? Can I see your BPC card?
- Will I get a compliance certificate when the job's done?
- On my terrace, where do the box gutters drain, and is there an overflow if the outlet blocks?
- Are any of my flashings lead, and will they react with new Colorbond or ZINCALUME?
- Do I have enough downpipes for the length of gutter, and are they near the valleys?
- If the old gutters or downpipes might be asbestos cement, how will you deal with them?
Who's allowed to do roof plumbing in Victoria
Victoria calls it roofing (stormwater) work. It covers installing, repairing or replacing any roof covering or flashing, and the gutters, downpipes and pipes that carry stormwater away. It doesn't cover tile, concrete or slate roof coverings, or cleaning and painting gutters unless something is connected, disconnected or altered.
Only a licensed plumber can do work that needs a compliance certificate. A registered plumber can do it under a licensed plumber's supervision. For plumbing work worth $750 or more, you should get a compliance certificate, and plumbers carry a Building and Plumbing Commission ID card you can ask to see.
What we'd do first
If you own a terrace, we'd have the box gutters and rainwater heads checked and cleared before spring, and ask whether an overflow can be added if there isn't one. It's a small job compared with a ceiling coming down in a February storm. Our national roof plumbing page explains the trade in more detail, and the Melbourne hub covers what else is different about roofs here.
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.
