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What coating should I choose when buying Self Drilling Metal or Timber Screws?

Which Screw Coating for Where?

Different builds need different rust protection. Class 4 is our preferred minimum across the galvanised screw range — we still stock some Class 3 and are slowly moving the range over. Find your build below and pick from the recommended coatings.

Where do you live	Preferred coating	Also works	Don't use
Inland (50+ km from coast) Sheds, garages, rural builds	Class 3 or Class 4	Hobson DX3 or DX4	—
Suburban or mild industrial Towns, light commercial, light industry	Class 4	Hobson DX4 (painted)	Class 3 alone (use Class 4)
Coastal within 1 km of surf Beach houses, coastal commercial	Class 4 minimum	Bremick B8, Hobson X9, Hobson DX4	Class 3
Beachfront (within 150 m of breaking surf) Ocean-front decks, salt-air homes	Bremick B8 or Hobson X9	Ruspert R1000+, Tykote (timber)	Class 3, Class 4 alone
Heavy industrial Aggressive chemicals, geothermal	Bremick B8 or Hobson X9	Ruspert R1500	Class 3, Class 4 alone
Outdoor timber, decks, landscape Treated pine, hardwood, retaining walls	Tykote (above-Class-4)	Class 4 for inland timber	Class 3
Roofing and cladding Sheet on purlin, sheet on stud	Hobson DX4 (colour-matched)	Bremick B8, Hobson X9	Class 3, plain galvanised

What about Class 5? There's no official Class 5 in AS 3566 — the standard stops at Class 4. When you see "Class 5" in marketing, it means a coating that goes above Class 4 (like B8, X9, Tykote or Ruspert R1000+).

Not sure which to pick? Send us your site postcode and what you're building — we'll match the right coating for your environment. Contact us or call 07 3192 9800.