How salt damages roofs
Onshore winds carry fine salt spray inland, depositing it on roofs, gutters and walls. Salt holds moisture against metal surfaces and accelerates corrosion. Rain washes exposed surfaces, but areas sheltered from rain, such as under eaves, behind parapets, beneath solar panels and inside gutters, accumulate salt and corrode first. The closer you are to breaking surf, and the more exposed the site, the faster this happens.
Steel roofing near the sea
Choose the right coating grade
Steel roofing manufacturers publish guidance on which products suit which environments, typically based on distance from breaking surf. Products designed for severe marine environments have heavier or more durable coatings. Using a standard product too close to the ocean can lead to early corrosion and may fall outside warranty conditions. Ask the roofer which product and grade they are specifying and check it against the manufacturer's guidance for your address.
Match the fixings
Screws and rivets corrode before sheets if they are of a lower class than the roofing. Fixings should be specified for the same exposure.
Flashings and accessories
Ridge capping, barge flashings, apron flashings and gutters should be made from compatible material of suitable durability. A durable roof with low-grade flashings fails at the flashings.
Avoid incompatible metals
Water running from copper pipes or lead flashings onto coated steel causes corrosion. So does contact between certain metals. Your roofer should detail these junctions properly.
Clean up swarf
Metal filings left on the roof after cutting rust quickly and stain the finish. A good roofer sweeps the roof and gutters at the end of each day.
Tiles near the sea
Concrete and terracotta tiles are not damaged by salt in the same way as steel. Terracotta in particular is very resistant. But a tile roof also has steel or other metal components: valley irons, flashings, nails or clips, and gutters. These need to suit the exposure. Ridge bedding and pointing also weather in coastal winds.
Gutters and downpipes
Gutters collect salt, leaves and sand, and stay damp. On coastal houses they are often the first part of the roof system to fail. Choose gutters of suitable material and grade, keep them clean and make sure they drain freely.
Maintenance that makes the difference
- Wash sheltered areas with fresh water as the manufacturer recommends, more often closer to the sea.
- Clear gutters and valleys of leaves, sand and debris.
- Check fixings periodically and replace any showing corrosion.
- Inspect flashings after storms.
- Keep trees trimmed so leaves do not hold moisture on the roof.
Signs of coastal corrosion
Look for white or rust-coloured deposits around fixings, blistering paint on sheltered areas, rust staining at laps, and gutters with pinholes or rust streaks. Early action, such as replacing fixings or treating small areas, is far cheaper than replacing sheets.
Planning a coastal re-roof
- Confirm the exposure category for your site.
- Specify roofing, fixings, flashings and gutters for that category.
- Include a roof blanket for condensation and heat.
- Detail junctions with other metals.
- Plan a maintenance routine from day one.
A coastal maintenance calendar
A routine keeps salt from doing its quiet damage.
- Before summer storms (around spring). Clear gutters, valleys and downpipes. Check ridge capping and flashings from the ground. Trim branches that touch the roof.
- Mid-summer. After any big storm, look for lifted sheets or tiles and check the ceiling for stains.
- Autumn. Wash sheltered areas of steel roofs and gutters with fresh water, as the manufacturer recommends, such as under eaves and beneath solar panels.
- Winter. Look in the roof space on a cool morning for condensation under steel and check fixings for white or rust-coloured deposits.
- Every few years. Have a roofer inspect the whole roof, including areas you cannot see from the ground.
Houses on exposed beachfront streets may need these checks more often. Owners further inland can stretch the intervals.
Related reading
See Colorbond roofing, best roofing materials for the Sunshine Coast climate and what causes roof damage on the Sunshine Coast.
General information for Sunshine Coast property owners, not advice about your particular roof. Rules, products and programs change; confirm with the authority named, or with Sunshine Coast Council or Noosa Shire Council, before acting.