Building a patio near the coast in South East Queensland: which steel, and how far from the surf?

South East Queensland has two kinds of coast. The Gold Coast beaches face the open ocean, with breaking surf throwing salt into the air all day. Moreton Bay, the Broadwater, the rivers and the canals are calm salt water. Both are hard on steel, but not equally, and BlueScope sets different rules for each.

If you live near either, the right steel for your patio comes down to one measurement. Here is how it works.

Building a patio near the coast in South East Queensland: which steel, and how far from the surf?

Breaking surf and calm water

Breaking waves throw a fine salt spray into the air, which the wind carries inland and drops on every surface. Calm water gives off far less. That is why BlueScope’s guidance treats a home 300 m from a surf beach very differently to one 300 m from a bay or a canal.

In our area, think of it this way

Breaking surf: the Gold Coast ocean beaches and the surf side of the bay islands.
Calm salt water: Moreton Bay and its bayside suburbs, the Broadwater, tidal rivers and the canal estates.
Where a site sits between the two, or faces strong onshore winds, BlueScope says to ask.

BlueScope’s distances for roofing

BlueScope publishes the minimum distance from the water for each of its products, through its SteelSelect guide, updated in 2023. For roofing:

COLORBOND® steel (the standard range): more than 200 m from breaking surf. It can be used close to calm salt water.
COLORBOND® Ultra steel: more than 100 m from breaking surf, and close to calm salt water. It has a heavier coating made for coastal sites.
For sites closer to breaking surf than that, BlueScope has a stainless product.
Unpainted ZINCALUME® steel: more than 200 m from breaking surf and more than 100 m from calm salt water.

BlueScope sets longer distances for walling, because walls are washed less by rain than roofs. That matters if a patio has steel screens or infill walls.

How the distance is measured

BlueScope measures from the high water mark, not from your front fence or the edge of the sand at low tide. On a canal lot that usually means the water line at high tide, which is only metres from the house. The local conditions count too: a home that looks over the water with nothing to block the wind gets more salt than one behind a row of houses at the same distance.

The unwashed parts of a patio

A roof sheet gets rinsed every time it rains. A patio has many places that never do: the underside of the gutters, the tops of beams under the roof, the gap under a flyover, the posts under a deck. Salt settles there and holds moisture. BlueScope’s warranties ask owners near the coast to wash those areas regularly with fresh water. A hose every few months does the job, more often right on the water.

Fixings and metals

Fasteners are chosen for the site, and near the water that means ones rated for marine conditions.
Different metals touching each other, such as copper or lead against steel, corrode quickly in salt air. We keep them apart and watch where water from other roofs runs.
Drill filings and cut offcuts are swept off the roof on the day, because they rust and stain the paint.

Council rules near the water

Coastal lots carry their own planning rules as well. Redland City Council keeps buildings and structures 9 m back from a canal wall, revetment wall or artificial lake, and its coastal protection overlay can send work to council for assessment. The City of Gold Coast restricts building near revetment walls on canal lots. We check those before we design, and our sister site RapidSitePlan can show you the mapping for your lot.

What we do on a coastal job

Measure the distance from your lot to the high water mark, and note whether it is surf or calm water.
Check the product and warranty against BlueScope’s guidance and its warranty estimator for your address.
Specify COLORBOND® Ultra steel or another suitable product where the distance calls for it.
Choose fixings, flashings and the panel for the site, not just the roof sheet.
Show you the washing routine before we hand over.

A good coastal patio

Waterfront patios are some of the best jobs we build. They also show up shortcuts faster than anywhere else. Using the right grade of genuine COLORBOND® steel for the distance, and keeping the sheltered parts rinsed, is what keeps one looking good. We bring samples of the standard and Ultra ranges to coastal quotes so you can see the difference.

COLORBOND®, ZINCALUME®, Activate® and Thermatech® are registered trade marks of BlueScope Steel Limited.