Term: nail head rusting

Nail head rusting refers to the visible rust stains or corrosion that appear on the surface of painted or coated materials—typically timber or cladding—caused by the oxidation of exposed or improperly coated steel nail heads. This occurs when non-galvanised or inadequately protected nails are used in exterior or moisture-prone environments. Over time, moisture causes the steel in the nail to rust, and the rust can bleed through the paint or coating, leading to unsightly brown or reddish stains.

Common Causes:

• Use of non-galvanised or low-quality steel nails.
• Damage to protective coatings during nail installation.
• Exposure to moisture or coastal environments.
• Inadequate surface preparation before painting.

Prevention:

• Use hot-dip galvanised, stainless steel, or specially coated nails.
• Countersink nails and fill over them before painting.
• Apply appropriate primers and sealants to prevent moisture ingress.
• Follow Australian Standards (e.g., AS 2311) for surface preparation and painting.

Impact:

Nail head rusting not only affects the appearance of a painted surface but can also compromise the integrity of the substrate over time if left untreated. It is a common defect noted in building inspections and painting maintenance reports.