Self-Drilling Screws

Self-drilling screws—widely known as Tek screws—feature a drill-bit point that bores its own hole and forms threads in a single driving operation, with no pilot hole required. They dramatically speed metal-to-metal and metal-to-wood fastening in construction, HVAC, roofing, and steel framing. We stock self-drilling screws across all drill-point capacities and head styles.

How Self-Drilling Screws Work

The fluted drill point removes material to bore a hole sized for the screw, then the threads engage and tap as driving continues—eliminating the separate drill and tap steps. This requires the point to drill through the full material thickness before the threads reach it, which is why drill-point capacity must match your material.

Drill Point Numbers

Drill points are numbered by capacity: #1-#2 for thin sheet metal (up to about 0.110"), #3 for medium steel, #4-#5 for heavy steel up to roughly 0.500" thick. Choosing the correct point number ensures the hole is fully drilled before threading begins; an undersized point in thick steel will overheat and fail.

Head Styles

Hex washer head: the most common, driven with a nut setter for high torque—standard in metal building and HVAC. Flat head: countersinks flush, for trim and panel work. Pan and bugle heads: for sheet metal and drywall-to-steel applications. Many include bonded sealing washers for weather-tight roofing and siding.

Materials and Finishes

Case-hardened steel with zinc or organic coatings: the standard for drilling capacity. 410 stainless: hardenable stainless that retains drilling ability with corrosion resistance, often with a carbon-steel drill point (bi-metal) for exterior and coastal use.

Dimensional Standards

Self-drilling screws follow ASME B18.6.4 (inch) and DIN 7504 (metric), specified by drill-point number and thread.

Selecting the Right Self-Drilling Screw

Match the drill-point number to your total fastened thickness—the point must clear the material before threads engage. Choose hex washer heads for structural steel and HVAC, sealing-washer versions for roofing. For exterior or coastal exposure, select coated or bi-metal stainless screws. Drive at the correct RPM with steady pressure; excessive speed burns the point.

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