Self-Drilling Screws (Tek Screws): Complete Guide to Types, Sizes & Applications

Self-drilling screws — commonly called Tek screws after the original brand — eliminate the need for a pilot hole by combining a drill bit tip with a threaded fastener. Using the wrong point number for your metal thickness results in stripped threads or a broken tip. Here is exactly what you need.

Self-Drilling Screw Point Number Chart

Thread Types for Different Applications

• Fine thread (SMS — Sheet Metal Screw): For metal-to-metal connections. Fine thread grips thin metal better than coarse. Standard for most Tek screw applications.
• Coarse thread: For metal-to-wood connections. Coarse thread bites into wood fiber while the drill point penetrates the metal first.
• Self-piercing (no drill point): For very thin sheet metal only. Pierces rather than drills — faster but limited to thin gauge.

Head Types

• Hex washer head: Standard for structural and roofing applications. Drive with 5/16" or 3/8" hex bit. High torque transfer, easy to spot-check tightness visually.
• Pan head Phillips: For lighter applications, electrical enclosures, HVAC. Lower profile than hex head.
• Bugle head: For metal stud framing where flush finish is needed — drywall to metal stud applications.
• Wafer head: Extra-large bearing surface for cladding and insulation panels.

Common Mistakes

• Wrong point number for steel thickness: A #2 point in 1/4" steel will break the tip before penetrating. Match point number to steel gauge.
• Too high RPM: Self-drilling screws drill best at 1,500-2,500 RPM. Too fast overheats the drill point and dulls it before penetrating.
• Not enough pressure: The drill point needs firm steady pressure to engage. Letting the screw spin without advancing work-hardens the steel surface.
• Overtightening: Strip threads instantly in thin sheet metal. Use a clutch setting or hex driver with a torque limiter.

Where to Buy

Canada:

United States:

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Frequently Asked Questions

What are self-drilling screws used for?

Self-drilling screws are used for metal-to-metal and metal-to-wood connections without pre-drilling. Common applications include metal stud framing, roofing and siding panels, HVAC ductwork, light steel framing, and attaching wood or rigid insulation to metal structure. The drill-point tip penetrates the metal eliminating the need for a pilot hole.

What is the difference between self-drilling and self-tapping screws?

Self-tapping screws require a pre-drilled pilot hole - they tap threads into existing holes but cannot drill through material. Self-drilling screws have a drill-point tip that drills the hole and taps threads in one operation with no pilot hole required. Self-drilling screws are faster and more common for light metal work.

What point number do I need for my metal thickness?

Match point number to steel gauge: Point 1 for up to 20 gauge (0.036 inch), Point 2 for up to 14 gauge (0.075 inch), Point 3 for up to 10 gauge (0.135 inch), Point 4 for up to 1/4 inch plate. Using too low a point number for your steel thickness will break the drill tip before penetrating.

What RPM should I use for self-drilling screws?

Drive self-drilling screws at 1500 to 2500 RPM. Too high RPM overheats and dulls the drill point before it penetrates. Too low RPM causes the screw to walk across the surface. Apply firm steady pressure while driving - insufficient pressure allows the surface to work-harden under the tip.

Can I use self-drilling screws in stainless steel?

Standard carbon steel self-drilling screws will not penetrate stainless steel - the tip dulls immediately. Use stainless steel self-drilling screws specifically rated for stainless-into-stainless applications, or pre-drill a pilot hole and use a standard stainless fastener. Always use cutting oil when drilling stainless steel.

Related Guides

• Screw Coating Guide — Which coating for outdoor metal work
• Structural Screws vs Lag Bolts — For wood framing connections
• Bolt Grades Explained — Grade 5 vs Grade 8 vs stainless
• Screw Size Selector — Get your exact screw spec instantly