Hot-dip galvanised
Hot-dip galvanised (HDG): steel coated by immersion in molten zinc. Minimum for outdoor bolts, coach screws, and fasteners in treated pine. AS/NZS 1214:2016.
Ask Chalkline about this →Hot-dip galvanised (HDG) refers to steel that has been coated with a layer of zinc by immersion in a bath of molten zinc at approximately 450 degrees Celsius. The zinc bonds metallurgically to the steel, producing a coating 45-85 microns thick for threaded fasteners (per AS/NZS 1214:2016) that provides both barrier protection and sacrificial cathodic protection against corrosion.
In Australian residential construction, HDG is the minimum specified coating for any fastener installed outdoors, in concrete, in treated timber (H2 and above), or in contact with masonry. Electroplated zinc (5-15 microns) is not an acceptable substitute in these conditions. For coastal locations within approximately 1 km of a surf coast, stainless steel 316 is preferred.
Also known as: HDG, hot-dipped galvanised, hot-dip zinc, galvanised (in trade shorthand, though this can also refer to electroplated zinc).
Category: Corrosion protection / coatings.
Standard: AS/NZS 1214:2016 covers HDG coatings on threaded fasteners M8-M64 (verified 2026-05-10, Standards Australia Store). AS/NZS 4680:2006 covers HDG coatings on fabricated steel articles (brackets, connectors, structural steel).
Related
- Coach screws for residential construction
- Bolts (M-series metric) for residential construction
- Galvanic corrosion (glossary)
See also
Last updated: 2026-05-10. Verified: 2026-05-10. Quarterly review for currency.