Self Drilling Screws
What are self-drilling screws?
Self-drilling screws (often called TEK® screws) have a drill-point tip that makes the pilot hole and taps threads in one step. They speed installation in steel studs, roofing and wall panels, and other metal-to-metal or metal-to-wood assemblies—no separate drilling required.
How do TEK drill-point numbers work on self-drilling screws?
The TEK number indicates the drill-point length/geometry and, by extension, the maximum steel thickness the screw can drill. Higher numbers are for thicker steel. Choose the point number specified on the product chart for your total stack-up.
- TEK 1–2 — thin sheet and light-gauge work
- TEK 3 — common for 14 ga and similar
- TEK 4–5 — heavier structural steel and thicker stack-ups
What head and drive options do self-drilling screws have?
- Hex-washer — high torque transfer and wide bearing for exterior panels and framing
- Pan / button / truss — broad bearing on thin sheet; clean appearance
- Flat (countersunk) — sits flush in a countersink for a smooth finish
- Roofing and siding heads — paired with sealing washers for weather-tight installs
- Drives — hex, Phillips, combo, Torx/6-lobe, and security drives
Which materials and finishes are best for self-drilling screws?
- Coated carbon steel — economical with corrosion-resistant coatings for exterior work
- 410 stainless — heat-treated magnetic stainless for hard drill points and good corrosion resistance
- 18-8 / 304 stainless — used on certain styles where maximum corrosion resistance is prioritized (drill-point capability varies)
- Zinc-plated steel — bright finish for dry interior environments
How do I size and specify self-drilling screws?
Order by diameter × thread × length (e.g., #10-16 × 1″, 1/4″-14 × 1-1/2″, M5-0.8 × 25 mm). Measure length from under the head (flat heads measured overall). Always match the TEK number to the total material thickness.
When should I use self-drilling screws vs self-tapping screws?
- Choose self-drilling to drill and tap in one step for steel studs, purlins, and panels
- Choose self-tapping when pilot holes are already present or for plastics/thin sheet that favor tapping points
Common applications for self-drilling screws
- Metal framing, purlins, and structural attachments
- Roofing and siding panels with sealing washers where required
- HVAC, electrical, and mechanical fastenings to steel
- Automotive, trailer, and equipment assembly
Installation tips for self-drilling screws
- Use the correct driver speed: let the drill point cut before applying full torque
- Keep the driver square; steady pressure minimizes walking and broken points
- Select sealing washers for exterior panels when specified
- For stainless threads, consider a compatible anti-seize to reduce galling
Safety and performance notes for self-drilling screws
- Verify steel thickness and stack-up against the product’s TEK rating
- Do not over-torque; stop when the washer seats and the panel is clamped
- Avoid mixing dissimilar metals that could cause galvanic corrosion
Self-Drilling Screws FAQs
See the accordion below for quick answers on TEK numbers, sizing, materials, head styles, and installation best practices.
Note — Guidance here is general. Always follow the product datasheet and job specifications.
Fasteners with a drill-point tip that makes the pilot and taps threads in one step—ideal for steel framing and metal panels.
Higher TEK numbers drill thicker steel. Match the TEK rating on the product chart to your total material stack-up.
Hex-washer for high torque and exterior panels; pan/button/truss for wide bearing and a cleaner look; flat head for a flush, countersunk finish.
410 stainless offers hardened drill points with good corrosion resistance. Coated carbon steel is economical and, with proper coatings and sealing washers, performs well outdoors. Choose based on environment and spec.
No, self-drillers create their own pilot. Keep the driver square and use the correct speed so the point can drill before the threads engage.
Measure from under the head to the tip (flat/countersunk measured overall).
Common causes: TEK number too low for the stack-up, excessive driver speed, misalignment, or work-hardened material. Verify TEK selection and slow the RPM.
Yes, select the appropriate TEK point for any underlying steel and consider galvanic compatibility between metals.
Self-drilling screws drill and tap in one step; self-tapping screws require a pre-drilled pilot and then form/cut the threads.