Self-drilling and self-tapping screws often get lumped together, with their names used interchangeably. But they’re not quite the same, and picking the right one can save you a lot of time (and hassle).
So let’s clear it up.
What’s the Difference Between Self-Drilling and Self-Tapping Screws?
At first glance, they can look very similar. Both are designed to create secure fixings without the need for traditional nuts, bolts or anchors, but there’s one key difference.
Self-drilling screws (often called Tek screws) have a built-in drill bit at the tip. They drill their own hole and tap the thread in one motion.
Self-tapping screws cut or form a thread, but still require a pre-drilled pilot hole before you drive them in.
Drilling a Pilot Hole for Self-Tapping Screws
Self-tapping screws such as coach screws are great when you're fixing into pre-drilled holes. They are most commonly used with timber but may also be used with plastics or soft metals.
They’re available in two main types:
- Thread-cutting: used for metal; they remove material to cut their thread.
- Thread-forming: used for plastics or soft materials; they push material aside to form a thread.
These are handy when you're working with more delicate surfaces, or where full drill points aren’t necessary. But, as we already mentioned, they do require the extra step of drilling a pilot hole.
All-In-One Self-Drilling Screws
As you might have guessed by now, self-drilling screws do all the work in one. Their drill tip at the end does all the work to create a hole and tap a thread with no tool change.
They're especially popular in:
- Roofing and cladding
- Steel frame construction
- HVAC and ductwork
- Timber-to-steel fixings
- Signage and outdoor installs
Because they combine drilling, tapping and fastening in one, they’re a common choice for time-sensitive jobs where speed and reliability matter.
For fixing metal-to-metal on site, you may choose self-drilling screws (preferably in A2 stainless steel if corrosion resistance matters).
Which Should You Use?
Here's a comparison table that should help you choose between these two types of fixings, depending on your application.
| Feature | Self-Tapping Screws | Self-Drilling Screws |
| Pilot hole required? | Yes | No |
| Has drill bit tip? | No | Yes |
| Materials | Timber, soft metals, plastic | Sheet metal, metal framework |
| Speed of use | Slower (2-step process) | Faster (1-step fix) |
| Common use | Pre-drilled setups | On-site installs, metalwork |
Stainless Steel Self-Drilling Screws for Roofers
At Fixabolt, we specialise in DIN 7504K stainless self-drilling screws for the the construction and roofing industries. These come with a hex flange head for easy driving and a hardened drill tip to get through steel sheeting without burning out. We are constantly expanding our range.
Final Thoughts
Both screw types have their place on site, and choosing the right one depends on the materials, time constraints, and finish required.
If you’re drilling into wood, plastic or thin sheet where a pilot hole isn’t an issue, self-tapping screws still have their place. But if you’re working with metal on a time-sensitive job, self-drilling screws can be a faster, more efficient option.
We’ve got a full range of A2 stainless steel self-drillers in the most popular sizes at trade prices with same-day dispatch to the site or the office.