Technically reviewed by Vincent, Founder at HEXVARO
Last reviewed
Key differences
| Factor | Self-drilling screw | Self-tapping screw |
|---|---|---|
| Pilot hole | Not needed | Usually needed |
| Tip | Drill point | Pointed or blunt tapping point |
| Typical use | Steel roofing, cladding, purlins, light-gauge framing | Sheet metal, plastics and pre-drilled parts |
| Common standards | ISO 15480, ISO 15481 | ISO 1479, ISO 7049 |
| Installation | One step with a screw gun | Drill first, then drive |
How to choose
- Check the total steel thickness, including any gap between sheets.
- Choose a self-drilling screw whose drilling range covers that thickness.
- Choose a self-tapping screw when the hole is already drilled or the material is not suited to a drill point.
- For roofing, specify the washer type and coating as well as the screw.
What to state in an RFQ
- Screw type, head and drive.
- Size × length, for example ST5.5 × 25.
- Material being fixed and the total steel thickness.
- Finish, washer type and any corrosion requirement.
- Quantity per size, packing and destination.
Frequently asked questions
Are self-drilling screws the same as Tek screws?
Yes, in everyday use. Tek is a brand name that is widely used for self-drilling screws.
Do self-tapping screws need a pilot hole?
Usually, yes. The hole must suit the screw size: too large and it will not hold, too small and it can crack the material.
Can a self-drilling screw be used in thick steel?
Only within its drilling range. Heavier steel needs a longer, heavy-duty drill point, so tell the supplier the steel thickness.
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