When it comes to choosing the right screw for the job, corrosion resistance and strength are vital, especially in New Zealand conditions. There are three common options available with hardware, galvanised, stainless steel 304, and stainless steel 316. Understanding the differences between them can save you from rust, failed fixings, or overspending on materials.
Galvanised Screws
Best for: General outdoor use, treated timber, fencing
Galvanised screws are coated with a layer of zinc to protect the steel underneath from rust. They’re tough, cost-effective, and perfect for most outdoor jobs as long as the coating stays intact. If the zinc layer gets scratched or wears away, corrosion will set in.
Pros:
- Affordable
- Good corrosion resistance in dry or moderate environments
- Great with treated pine
Cons:
- Can rust over time, especially near the coast
- Coating can chip during installation
Stainless Steel 304 Screws
Best for: Kitchens, bathrooms, light coastal areas
304 stainless is the most common grade used in stainless fixings. It has good corrosion resistance and won’t rust or stain under most conditions. However, it is not indestructible as in salty air or marine environments 304 may pit or degrade.
Pros:
- Strong corrosion resistance
- Won’t flake or peel like galvanised coatings
- Clean, tidy finish
- Great for Kwila decking
Cons:
- Pricier than galvanised
- Not ideal for aggressive coastal or marine zones
Stainless Steel 316 Screws
Best for: Coastal areas, marine builds, high-exposure zones
The ultimate premium option. 316 stainless includes molybdenum (try saying that three times fast), to give it extra protection against salt and moisture. If you’re working within 5km of the coast or anywhere with harsh exposure, 316 needs to be your go-to screw.
Pros:
- Excellent corrosion resistance, especially near saltwater or pools
- Long-lasting in harsh environments
- No coatings to wear off
Cons:
- Most expensive option
- May be overkill for sheltered or inland use
Painted Screws
Best for: Matching fixings to cladding, roofing, or decking
Painted screws are typically galvanised or stainless screws that have been coated with a weather-resistant paint that has been colour-matched to popular cladding and roofing systems. The coating adds an extra layer of protection and helps the fastener blend in visually and just like the unpainted screws they come in a range of sizes and head types.
Pros:
- Great for aesthetics—blends in with surfaces
- Added weather protection
- Common in roofing, cladding, and decking
Cons:
- Paint can chip during installation if not careful
- Underlying material still matters (galv vs stainless)
Making sure you use the correct hardware is important for your outdoor project to stand the test of time. A little planning can prevent big problems later, so call into Canterbury Timber and Hardware or give us a call and we will help you choose the right screw for your next project.