What Newcastle asks of roof drainage
Downpours, not drizzle
The Pasha Bulker storm of June 2007 dropped 164.6 mm on Newcastle between 3 pm and 9 pm. June is also the wettest month on average at Nobbys, at 125.2 mm, and inland is wetter than the coast: the university station averages 1,111.2 mm a year against 1,034.5 mm at Nobbys.
Box gutters behind terrace parapets
In Cooks Hill, the council asks owners to keep the parapets that hide terrace roofs from the street, and Newcastle East is mostly two and three storey terraces. Roofs behind parapets drain through box gutters, which overflow inside the building if they block or are undersized.
Salt near the surf
For eave gutters, downpipes and fascia, BlueScope recommends Zincalume and Colorbond more than 200 m from salt marine influence, and Colorbond Ultra more than 100 m. Closer to Merewether, Bar Beach or Stockton's ocean side, ask what's rated for your spot.
How roof plumbing should be sized
The NCC sizes eaves gutters for a five-minute burst of rain with a 5% chance of happening in any year, and asks for overflow measures to handle heavier rain. Each downpipe may serve no more than 12 m of gutter and should sit as close as possible to a valley. Valley gutters need a roof pitch over 12.5 degrees and at least 15 mm of freeboard (spare depth above the water line).
Box gutters can be designed to AS/NZS 3500.3 for size, fall and overflow. If an old terrace box gutter overflows in every big storm, it may be undersized rather than blocked, so ask a roof plumber to check its size and outlets. Our page on box gutters explains the options.
On bush fire prone land, the NSW Rural Fire Service suggests avoiding box gutters and flat roofs on new work, so an inland renovation is a chance to rethink them.
Who's licensed for roof plumbing in NSW
NSW treats roof plumbing as its own licence category, separate from ordinary plumbing. It covers gutters, downpipes, flashings, metal roofs, skylights, ventilators and protective coatings, and a contractor needs the licence once the job is worth more than $5,000 including GST. A plumber's licence alone doesn't include it, so check the categories on the NSW Government's online licence check.
Questions for a Newcastle roof plumber
- Does your NSW licence include the roof plumbing category?
- Are my gutters, downpipes and outlets big enough for a storm like June 2007?
- Where does water go if the box gutter overflows, and is there an overflow outlet?
- Is the steel you're using rated for my distance from the surf?
- If the job is over $5,000, will I get a written contract?
What we'd do
We'd have gutters, box gutters and downpipes checked in April, before the wettest months, and we'd fix the size of anything that overflows rather than just clearing it again. On a terrace, the box gutter is the first thing we'd ask about. The national roof plumbing page explains each part, and the Newcastle page covers the local storms.
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.