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Screws for Decking
Screws only for Timber

Screws only for Timber

Screws only for Timber

Not sure what screw size you have or need?

Two ways to confirm before you order - whichever you already know.

1If you have a screw in hand

Measure across the outside of the thread - not the shank - to get the gauge (a 10g decking screw measures about 4.8mm). Screw gauges have a wider tolerance than bolts, so treat it as a close match rather than exact. Then measure the overall length, head included - decking screws are countersunk.

Open the screw gauge sizing chart ›

2If you know the gauge

Every product page carries a Screw Gauge and TPI chart for its range - every gauge links straight to the product. Coarse threads suit treated pine and softwood decking; fine threads suit hardwood boards like merbau and spotted gum.

T17 decking screw side profile showing where to measure

T17 type 17 point - gauge is measured across the thread.

Decking Screws for Timber Joists

The traditional Australian deck: timber bearers and joists with timber boards on top. Type 17 self-tapping decking screws have a sharp self-drilling point that bores its own pilot in the timber, so you can drive direct into hardwood without pre-drilling (except on dense species like Jarrah and Spotted Gum, where a 3mm pilot helps). BNA stocks the full size range in stainless and galvanised finishes.

Sizes & Specifications

Gauges: 8g, 10g, 12g (10g is the workhorse). Lengths: 50mm, 65mm, 75mm, 90mm. Head styles: Countersunk (hardwood), Bugle-batten (softwood). Drives: Square SQ2, T20/T25 Torx, Pozi PZ2. Finishes: Class 3 / Class 4 galvanised, Stainless A2-70 G304, Stainless A4-70 G316.

Recommended Use

Match the screw finish to the timber and the environment. On hardwood (Jarrah, Merbau, Spotted Gum) use stainless only - the tannins in hardwood react with zinc and cause black staining around galvanised screw heads. On softwood (treated pine, radiata) galvanised Class 3 or Class 4 is fine inland; stainless G304 within 50km of the coast; stainless G316 within 300m of the sea.

Browse the full BNA range at Screws for Decking or see our Technical PDFs library for spec sheets.

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