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Countersunk Timber Screws

Countersunk Timber Screws

Countersunk Timber Screws

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 (an 8g screw measures about 4.2mm). Screw gauges have a wider tolerance than bolts, so treat it as a close match rather than exact. Then measure the length - countersunk timber screws are measured overall, head included.

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. Rule of thumb for timber: coarse threads for softwood and framing, fine threads for hardwood.

T17 timber screw side profile showing where to measure

T17 timber screw - gauge is measured across the thread.

Countersunk Bugle Batten timber screws are the workshop default for decking, batten and general framing work. The bugle-batten head sits flush in the timber face after countersinking through the top board; the part-thread design lets the upper board pull tight to the joist; the T17 self drilling tip eliminates pre-drilling in pine, treated pine and most softwood.

Also known as: Bugle Batten Screw, Deck Screw, Batten Screw, In-Hex Screw, T17 Timber Screw, BT Screw.

12g (5.50mm) and 14g (6.30mm) shanks in part-thread configuration. In-Hex (5mm) drive. Lengths 50mm through 200mm cover decking, batten work, framing and structural timber-to-timber. Galvanised Class 4 finish for treated-pine exposure tolerance.

GRADES AND MATERIALS

Zinc Yellow (Class 2): zinc plate with a yellow chromate passivation - interior and dry, sheltered work. Galvanised (Class 3, 4, B8 and X9): galvanised finishes for exterior and structural work and treated-pine exposure - the higher the class, the harsher the environment it suits. Higher Classes and painted variants available.

DRIVE AND INSTALLATION

Drive with an In-Hex (5mm) bit in a powered driver at 1000-2000 RPM depending on timber density. The bugle head reams a clean countersink in the timber face as the screw enters; the part-thread design means the upper board pulls tight to the joist below. For dense hardwood, pre-drill a 75-80% pilot to prevent splitting.

SIZE AND THREAD

12g standard for board-to-joist decking and 19-32mm batten work; 14g for heavier structural-to-structural framing. Length = top board + joist engagement. For 32mm decking on 75mm joist, a 75mm screw provides ~38mm of base engagement (ideal).

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