Question 1

Why do decking screws have a partial thread rather than a full thread?

Accepted Answer

A partial thread, used on lengths of 65mm and above, grips only the lower joist rather than both boards at once. This pulls the top board tight against the joist and prevents timber jacking, where two boards are held apart creating a gap or raised surface.

Question 2

Are these screws suitable for pressure-treated timber?

Accepted Answer

Yes. The green organic coating provides up to 1,000 hours of salt spray resistance, making these screws compatible with standard pressure-treated softwood decking and fencing. For highly aggressive environments or prolonged contact with modified timbers, a stainless steel fixing may be worth considering.

Question 3

Which size decking screw should I use for standard 28mm deck boards?

Accepted Answer

For 28mm thick deck boards fixed to 47mm joists, the 5.0 x 75mm screw is a practical choice, giving sufficient thread engagement into the joist without breaking through the underside. The 5.0 x 100mm option suits thicker boards or double-joist details at frame ends.

Property	Detail
Drive Type	Pozi
Treatment	Green organic coating
Corrosion Resistance	Up to 1,000 hours salt spray
Thread	Partial thread on lengths 65mm and above (prevents timber jacking)
Available Sizes	4.5 x 50mm, 4.5 x 65mm, 5.0 x 75mm, 5.0 x 100mm
Pack Sizes	Box of 100 or Box of 200 depending on size
Intended Use	External timber, decking, fencing, landscaping

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Decking Screws

John George Pozi Drive Decking Screws