13mm x 4.2mm Coloured Wafer Head Self-Drilling Screws - RAL Powder-Coated BZP Steel

Coloured 13mm x 4.2mm Wafer Head Self-Drilling Screws

These 13mm x 4.2mm coloured wafer head self-drilling screws are the shortest fixing in the wafer head range, built for stitching drywall and ceiling track systems, thin sheet metal, and tight assemblies where every millimetre of clearance behind the steel counts. Most of the 13mm shank is self-drilling point with a short, fast-engaging thread - the screw bites two thin layers of steel and pulls flush without excess length protruding behind the fixing.

The integrated self-drilling point penetrates steel up to 3.0mm thick without a pilot hole, and the wafer low-profile head distributes load across a wider surface area than traditional pan or countersunk heads, reducing pull-through risk on thin materials and sitting flatter against the finished surface. The 4.2mm diameter drives quickly with minimal material stress, giving clean results in thin substrates and tight spaces.

Manufactured from carbon steel with a bright zinc plated (BZP) base and finished in a durable RAL powder coat, each screw head is colour-matched to the surface it sits against. Where fixings are visible on ducting, cable containment, exposed framing, or thin cladding, a colour-matched wafer head blends into the installation rather than standing out as a row of zinc dots across an otherwise clean surface.

41 RAL Colour-Matched Finishes

Every 4.2 x 13mm wafer head screw is electrostatically powder-coated and oven-cured to a RAL Classic colour standard. The result is a hard, uniform finish bonded directly to the screw head - resistant to scratching, chipping, UV fading, and general site wear. Unlike wet paint, powder coat will not peel, blister, or thin at edges over time.

With 41 stocked RAL colours spanning whites, greys, blacks, blues, greens, reds, yellows, browns, and purples, these coloured wafer head screws cover the most commonly specified colours across framing, ducting, signage, and light cladding applications. Whether you are matching RAL 7035 Light Grey plant enclosures, RAL 9010 Pure White ceiling systems, RAL 9005 Jet Black exposed ductwork, or RAL 7016 Anthracite Grey framing, the right colour is available for immediate dispatch.

Need a RAL colour outside the stocked range? We hold over 400 RAL Classic powders and can coat to any colour on request. Contact us with your RAL reference for availability and lead times.

Common Applications

4.2 x 13mm coloured wafer head self-drilling screws are used wherever the shortest possible colour-matched stitching fix into thin steel is required:

• Drywall and ceiling track - track stitching, ceiling grid systems, and partition framing
• Metal stud framing - stud-to-track stitching where clearance behind the steel is critical
• Thin sheet metal stitching - two thin layers of steel, folded metal joints, and lap fixings
• Ducting and cable containment - HVAC ductwork, cable trays, and trunking covers
• Light cladding and trims - thin panel fixings, cover strips, and flashings where minimal protrusion is needed

Specification

Frequently Asked Questions

What are 13mm wafer head self-drilling screws used for?

They are the shortest stitching length in the wafer head range, made for joining drywall and ceiling track, stitching metal stud to track, and fixing thin sheet metal and ductwork where a flush, low-profile head and absolute minimum protrusion behind the steel are essential. With a short thread and long drill point relative to the overall length, they are purpose-built for thin, tight assemblies rather than any real material build-up.

What thickness of steel can these screws drill through?

The self-drilling point is designed to drill and tap steel up to 3.0mm thick, as well as aluminium and other light-gauge metals, without the need for a pilot hole.

When should I use 13mm rather than a longer wafer head?

Choose the 13mm when you are stitching the thinnest track or sheet and want the shortest, flattest fixing possible - two thin layers of steel with nothing behind them. Because most of the 13mm length is drill point with only a short thread, step up to 16mm or 19mm as soon as there is material build-up, insulation backing, or a deeper section to bite into.

What is the difference between a wafer head and a flange head screw?

Both head types sit low and distribute load across a wide area, but they differ in profile and application. A wafer head is thinner and flatter - sitting closer to flush against the surface - making it the better choice where minimal head protrusion is critical, such as stud-to-track stitching where boards or services sit tight behind the steel. A flange head stands slightly higher with a more pronounced washer effect, providing greater pull-through resistance on thin panels. Choose wafer for stitching and minimal protrusion; flange for panel clamping.

What driver bit do I need for these screws?

These wafer head screws have a Phillips PH2 recess. Use a standard PH2 driver bit - apply firm, consistent pressure at controlled speed to avoid cam-out. Compatible with all cordless drivers and hand screwdrivers.

Powder Coated Self-Drilling Screws

RALfixings specialise in colour-matched visible fixings for the signage, framing, and construction sectors. Every self-drilling screw is powder-coated in-house using an electrostatic spray process, then oven-cured at 200°C to produce a hard, even finish that bonds directly to the screw head.

Powder coating outperforms wet paint in every measurable way. The electrostatically charged powder particles wrap around the low-profile wafer head and into the Phillips recess, building a consistent film thickness that liquid paint cannot replicate. The cured finish is harder, more flexible, and far more resistant to impact, abrasion, and chemical exposure than paint, standing up to outdoor exposure, repeated handling, and long-term use on site.

Benefits of powder coated self-drilling screws:

• Scratch resistant - hard cured finish withstands handling, installation, and site wear
• Rust resistant - BZP base plus powder coat provides dual corrosion protection
• UV resistant - colour stays true with no fading or chalking
• Weather resistant - will not peel, blister, or crack in exterior conditions
• Colourfast - RAL colour-matched finish maintains consistency over time

Available RAL Colours

4.2 x 13mm coloured wafer head self-drilling screws are stocked in the following 41 RAL Classic colours. Select your colour from the dropdown above, or view the full RALfixings colour guide for additional RAL colours available on request.

• RAL 1013 Oyster White
• RAL 1015 Light Ivory
• RAL 1016 Sulphur Yellow
• RAL 1019 Grey Beige
• RAL 1020 Olive Yellow
• RAL 1023 Traffic Yellow
• RAL 1033 Dahlia Yellow
• RAL 1036 Pearl Gold
• RAL 3002 Carmine Red
• RAL 3004 Purple Red
• RAL 3009 Oxide Red
• RAL 3020 Traffic Red
• RAL 4006 Traffic Purple
• RAL 4007 Violet Purple
• RAL 4010 Telemagenta
• RAL 5003 Sapphire Blue
• RAL 5004 Black Blue
• RAL 5012 Light Blue
• RAL 5013 Cobalt Blue
• RAL 5023 Distant Blue
• RAL 5024 Pastel Blue
• RAL 6003 Olive Green
• RAL 6005 Moss Green
• RAL 6009 Fir Green
• RAL 6012 Black Green
• RAL 6016 Turquoise Green
• RAL 6024 Traffic Green
• RAL 6025 Fern Green
• RAL 6027 Light Green
• RAL 7009 Green Grey
• RAL 7016 Anthracite Grey
• RAL 7032 Pebble Grey
• RAL 7035 Light Grey
• RAL 7038 Agate Grey
• RAL 7042 Traffic Grey A
• RAL 8004 Copper Brown
• RAL 8008 Olive Brown
• RAL 8019 Grey Brown
• RAL 9005 Jet Black
• RAL 9010 Pure White
• RAL 9016 Traffic White