Metal Screws & Self-Drillers for Steel-to-Steel Connections
Self-drilling “TEC” screws save time on site: the drill-point pierces the sheet, taps the thread and clamps the joint in one hit—no pre-drilling or swarf. Spechunter stocks both zinc-flake carbon steel and full A2 stainless lines, so you can tackle everything from light SFS studs to heavy façade rails in coastal exposure.
Quick-pick guide
| Common task | Screw series | Diameters & lengths | Steel thickness* | Link |
|---|---|---|---|---|
| Fix sheathing boards or brackets to SFS studs | Ancon HTSS-W two-point screws | 6.3 mm × 115, 150, 180 mm | 1.2 – 3.0 mm | HTSS-115-W |
| Stitch heavy-gauge rails or restraint plates | Evolution TSBW heavy-section TEC (EPDM washer) | 5.5 mm × 50, 85 mm | up to 12 mm | TSBW 85-5 |
| Coastal or pool environments | Evolution BMHH A4 stainless TEC | 5.5 mm × 50 mm | 3 – 6 mm | BMHH 55-50-3 |
| Channel-tie compression sleeves | Evolution SSCS10 (supplied with sleeve) | 6.3 mm × 100, 110 mm | ≤ 3 mm | SSCS10-100 |
*Steel stack thickness the drill-point will penetrate without pilot drilling.
Why buy your metal screws here
ETA data sheets ready for your O&M file.
304 and 316 stainless for BS EN 1993 durability class C4 sites.
Captive EPDM washers on heavy-section screws keep façades watertight.
Lengths up to 240 mm—fix through 200 mm of insulation in one pass.
Order by 12:00, spend £200 ex-VAT and most postcodes get free next-day delivery (see our delivery information).
How to achieve a perfect install
Drive at 1 800 – 2 500 rpm with an 8 mm nut-setter; wait until the flute clears before the washer seats.
For cavities over 150 mm slip a stainless compression sleeve over the shank to stop cold-bridge “whip”.
Keep minimum 14 mm edge distance in C30/37 concrete or S275 sheet to maintain full pull-out values.
Match metals: stainless screws with stainless plates such as the 25/14 Channel System to avoid bi-metallic staining.
FAQs
Do I need a pilot hole? – Not for stacks up to the drill-point rating (see table). Thicker plate needs a 5 mm pilot and a self-tapper.
Torque setting? – Stop as soon as the EPDM washer just mushrooms; over-tightening splits the seal.
Are carbon screws OK outside? – Zinc-flake coating is fine for sheltered elevations; choose A4 stainless within 5 km of the sea or aggressive atmospheres.
Removable? – Yes. Back out with the driver; the thread retains full strength if re-tightened once.
Complete your fixing kit with Concrete & Masonry Screws for slab anchors, Light Anchors for battens, and Stress Plates for façade insulation. Need pull-out figures or a toolbox talk? Contact us or call 0118 922 7941—Spechunter will chase down every spec for you.
Spechunter.co.uk – Chasing down specialist construction specifications since 1988. Fact Checked and Updated May 2025.
