Sheet Metal Screws
What are sheet metal screws?
Sheet metal screws are self-tapping fasteners with sharp points and machine-style threads that create their own mating threads in a pre-drilled pilot hole. They provide strong, reliable attachment to thin steel, aluminum, stainless, plastics, and composites where a nut or tapped hole isn’t available.
Which types of sheet metal screws are there?
- Type A / Type AB — general-purpose sharp-point styles; AB has a finer pitch for better grip in thin sheet and aluminum.
- Type B — blunt point for pre-tapped or thicker materials where a sharp point isn’t required.
- Thread-forming / thread-cutting — specialty points for plastics or thin metals when lower drive torque or chip control is needed.
What head and drive options do sheet metal screws have?
- Pan, button, truss — wide bearing on thin sheet.
- Flat (countersunk) — sits flush for a smooth finish.
- Hex-washer — high torque and large bearing area for exterior panels.
- Drives — Phillips, combination, Torx/6-lobe, slotted, hex-socket, and security drives.
Which materials and finishes are best for sheet metal screws?
- Zinc-plated steel — economical for dry interiors.
- 18-8 / 304 stainless — dependable outdoor/indoor corrosion resistance.
- 316 stainless — enhanced resistance for coastal or chemically aggressive settings.
- Black phosphate — low-glare indoor finish and good paint bond.
How do I size and specify sheet metal screws?
Order by diameter × threads per inch × length (e.g., #8-18 × 1″, #10-16 × 3/4″). Length is measured from under the head; flat heads are measured overall. Metric options follow ISO pitch (e.g., M4-0.7 × 20 mm).
Do I need a pilot hole for sheet metal screws?
Yes. Drill the recommended pilot slightly smaller than the screw’s major diameter so the threads form properly. Deburr holes to reduce drive torque and improve thread quality. For no-pilot installs in steel, use self-drilling screws instead.
Common applications for sheet metal screws
- HVAC ducting, enclosures, brackets, and electrical panels
- Automotive, appliance, and equipment assembly
- Roofing, siding, and architectural panels (use sealing washers where required)
- General fabrication in thin steel, aluminum, and stainless sheet
Installation tips for sheet metal screws
- Use the correct pilot size; keep the driver square and apply steady pressure.
- Select head/drive to match tools and needed bearing area; avoid over-torque that can strip thin sheet.
- Use sealing or finish washers for weather-tightness or surface protection.
- Consider compatible anti-seize on stainless-to-stainless joints to reduce galling.
Sheet Metal Screws FAQs
See the accordion below for answers on sizing, pilots, head/drive selection, materials, and when to choose self-drilling alternatives.
Note — Guidance here is general. Always follow the product datasheet and job specifications.
Self-tapping screws with sharp points and machine-style threads that form mating threads in a pre-drilled pilot hole for thin metals and plastics.
Sheet metal screws require a pilot hole; self-drilling screws have a drill point that creates the pilot and taps in one step for steel framing and panels.
Type A is common for general use; Type AB has finer pitch for better engagement in thin sheet and aluminum; Type B has a blunt point for pre-tapped or thicker materials.
Use the product pilot chart. Pilots are usually slightly smaller than the screw’s major diameter; deburr for cleaner threads and lower driving torque.
Measure from under the head to the tip—except flat/countersunk heads, which are measured overall.
Pan/button/truss for wide bearing on thin sheet, flat for a flush finish, hex-washer for higher torque and exterior panels.
Zinc-plated for dry interiors; 304 (18-8) for most outdoor/indoor environments; 316 for coastal or chemically aggressive settings.
Yes, use appropriate thread-forming or thread-cutting styles and correct pilots to prevent cracking.
Use a finer-pitch Type AB, correct pilot, and controlled torque; consider a wider head or washer to spread load.
Use sealing/finish washers for weather-tightness or surface protection; apply thread-locking methods where vibration is present.