STAINLESS STEEL UNIVERSAL SCREWS

SPAX Universal Screws

The Universal Screw is the general-purpose screw in the SPAX range and the one that covers the widest span of everyday work: general joinery, second fix, and external woodwork where a stainless fixing is wanted. It uses a countersunk head that pulls flush into the timber surface, the T-STAR plus drive, and the 4CUT point, and is stocked in A2 stainless from 3.5mm to 6.0mm diameter in lengths from 16mm to 100mm.

Materials Stocked in A2 (304-equivalent) stainless steel with a plain finish, giving good general corrosion resistance for exterior joinery and damp interior use. For coastal or chloride-exposed work, look at the A4 options in the Decking Screw range or ask about availability in A4 for the size required.

Head and drive The countersunk head is designed to sink flush with the timber surface without needing a separate countersink operation in most softwoods. The T-STAR plus recess takes a T15 to T30 bit across this family, rising with diameter: the 3.5mm and 4.0mm sizes take T15 or T20, the 5.0mm sizes T20 or T25, and the 6.0mm sizes T25 or T30. The correct bit size is listed against each product.

Sizes Diameters run 3.5, 4.0, 4.5, 5.0 and 6.0mm, with lengths from 16mm up to 100mm. Shorter lengths in the smaller diameters suit trim, beading and light assembly work, while the 5.0mm and 6.0mm sizes at 60mm and above are the general-purpose structural-adjacent sizes for framing, battening and heavier joinery.

FAQs

What is a Universal Screw actually for? It is the default choice where no more specialised screw applies. If the work is general timber-to-timber fixing, joinery, battening or external woodwork, and there is no specific requirement for a washer head, a sealing washer or a particular finish, the Universal Screw is the size-for-size option. Where the fixing is structural, or into decking boards, or through roof sheets, use the Timber Construction, Decking or Sealing screw respectively.

How do I choose the right length? The usual working rule for timber-to-timber fixing is that roughly two thirds of the screw length should sit in the receiving timber. Measure the thickness of the piece being fixed, then add at least twice that again for the penetration depth, and select the nearest stocked length up. Avoid selecting a length that will break through the far face unless that is intended.

Will the countersunk head pull flush without pre-countersinking? In most softwoods, yes. In hardwoods, in engineered boards, and where the surface finish matters, countersinking first will give a cleaner result and avoids the head crushing fibres around the hole as it seats.