Colorbond Ultra, Colorbond or Zincalume on the Northern Beaches

Why the coast changes the choice of steel

Salt spray settles on steel roofs and on the steel around them. BlueScope publishes a selection guide for its roofing steels that sets a minimum distance from the sea for each product, and its Lysaght brand publishes advice on the screws that go with them. On the Northern Beaches, with the ocean on one side of the peninsula and Pittwater or the harbour on the other, it’s the first question to settle before a new metal roof is ordered.

Colorbond Ultra, Colorbond and Zincalume: BlueScope’s distances

This is BlueScope’s own table, with its product names and distances exactly as published. Each product is recommended only beyond the distance shown.

BlueScope TB-1A: recommended steel for roofing in marine environments

BlueScope Technical Bulletin TB-1A, “Steel roofing products – selection guide”, March 2023, revision 14, Table 1, copied as published and checked 1 October 2026. Its notes: “* For commercial applications”; “Distance is as measured from the high water/tide mark.”; “Absolute performance is subject to local conditions including, but not limited to, prevailing winds, and presence of unwashed areas.” The bulletin calls the table “a GUIDE ONLY” and says “it is essential to consult with Steel Direct for advice on the most suitable choice of product.”

Read across the rows and three things stand out:

• Zincalume vs Colorbond. Zincalume, the unpainted silver steel, sits in the strictest row for houses: more than 200 m from breaking surf and more than 100 m from calm water. Standard Colorbond needs the same 200 m from surf but has no minimum from calm water.
• Colorbond Ultra halves the surf distance to more than 100 m.
• Closer than 100 m to breaking surf, the only roofing product in the table is Superdura stainless steel.

BlueScope adds that “Absolute performance is subject to local conditions including, but not limited to, prevailing winds, and presence of unwashed areas”. A home on an exposed ridge facing the sea isn’t the same as one tucked behind other houses at the same distance.

The seven Colorbond Ultra colours

If the table puts your house in Colorbond Ultra, the colour choice narrows. BlueScope’s colour chart lists seven of its 22 roofing colours in Ultra:

The full range of 22 is on our roof replacement page.

Ocean surf or calm water: which column is yours?

The table has two columns: “breaking surf or exposed marine” and “calm marine”. BlueScope doesn’t say which Northern Beaches suburbs fall in which, so this is our reading of it:

• Breaking surf. The ocean beaches from Manly and Queenscliff up through Curl Curl, Dee Why, Collaroy, Narrabeen, Mona Vale, Newport, Avalon Beach, Whale Beach and Palm Beach face open surf.
• Calm marine. The sheltered bays of Pittwater, such as Church Point, Bayview, Clareville and Scotland Island, and the harbour side around Seaforth, Clontarf and Manly Cove face calmer water.
• Both. Narrow parts of the peninsula, around Palm Beach and Avalon, have the ocean on one side and Pittwater on the other. Measure to each and use whichever gives the stricter answer.

Where a home sits on a headland or the entrance to a bay, the line between the two isn’t clear. That’s a question for the roofer to put to BlueScope, which says it’s “essential to consult with Steel Direct for advice on the most suitable choice of product”.

How to work out your distance

1. Open a map with a measuring tool and find the high water mark: BlueScope’s note says “Distance is as measured from the high water/tide mark”, not from the waterline at low tide or from your street address.
2. Measure in a straight line from there to the nearest edge of the roof, not the front gate.
3. If you’re near both the ocean and Pittwater or the harbour, measure to each.
4. Ask the roofer to write the product (Colorbond in a Classic or Matt finish, Colorbond Ultra, Zincalume or Superdura stainless) and the screw class into the quote, so you can check both against the tables on this page.

Screws and fixings near the sea

The sheets are only part of it. Lysaght’s fastener bulletin sets the screw class by exposure, and its distances are framed differently from BlueScope’s, so it’s shown here as a separate table rather than lined up with the one above.

Lysaght PAB04: screw class by exposure

Lysaght Product Advisory Bulletin PAB04, “Fasteners”, January 2024, Table 4.1, in our own short form, checked 1 October 2026. The bulletin’s general rule is “You should use screws to AS 3566.1 Class 3 (or better)”, and it says “Stainless steel fasteners are recommended for use only with SUPERDURA® Stainless steel.” Its distances are measured “from marine environments”, not from breaking surf, so don’t line them up with BlueScope’s table above.

On a metal roof, corrosion often shows first at the fixings and cut edges. If you’re getting a new roof or a restoration near the coast, ask which class of screw is going in.

Washing and maintenance in salt air

BlueScope’s maintenance bulletin (TB-4) says coated steel in “unwashed areas”, the places rain doesn’t reach, needs regular cleaning. It lists fascias, wall cladding under the eaves, garage doors and the underside of eave gutters, carports and patios, and says “Washing should be done six monthly as a minimum, or three monthly in locations such as coastal areas where marine salt spray is prevalent”.

Lysaght’s installation manual says “Maintenance is probably the biggest factor” in how long its roofing lasts, and lists “Regular washing down, especially near coastal or industrial influences” and clearing leaves and debris from gutters, downpipes and leaf guards. On a leafy block, keeping the gutters clear is part of the same job.

We’d rather you didn’t climb onto the roof to do it. Do what you can reach from the ground, and leave the roof itself to someone with the right safety gear.

What about tiles near the coast?

Tile makers argue tiles suit salt air better. Monier, a roof tile manufacturer, says on its FAQ page: “All Monier concrete and terracotta roof tiles are salt safe and will not corrode over time, however Terracotta is the ultimate roofing product in these conditions given its performance and also colour warranty of 30 years.” That’s a manufacturer’s claim about its own product, from a business that competes with steel. Tiles bring their own upkeep, in ridge capping and pointing, and the roof replacement cost guide compares published prices for each material.

Bush fire prone land

Northern Beaches Council publishes a bush fire prone land map for the whole council area, certified by the NSW Rural Fire Service on 7 August 2020; the council notes these maps are reviewed every five years. Replacing roof cladding can be exempt development under the NSW Codes SEPP, but to stay exempt on bush fire prone land the work must “be adequately sealed or protected to prevent the entry of embers” and “use equivalent or improved quality materials”. Check your property on the council’s bush fire prone land map or its section 10.7 planning certificate, and ask the roofer to confirm the approval pathway.

What needs a licensed roofer

In NSW, metal roofing is roof plumbing work, which the licence page defines as work on “guttering, downpipes, roof flashing and roof coverings”. Work worth more than $5,000 in labour and materials, including GST, must be done under a contractor licence in the right category, with a written contract that shows the licence holder’s name and licence number. Check it on the Service NSW licence register.

For prices on a new steel roof, see roof replacement cost; for the work itself, roof replacement and re-roofing.

Common questions