Question 1

What is a TEK® screw?

Accepted Answer

A TEK® screw is a self-drilling screw with a drill point formed into the tip, so it drills its own hole and forms its own thread in steel in one operation — no pre-drilling or tapping needed. The TEK® point number (TEK® 3, TEK® 5 and so on) indicates the thickness of steel the point can drill through.

Question 2

What's the difference between a TEK® 3 and a TEK® 5 point?

Accepted Answer

The point number relates to drilling capacity. TEK® 3 points are designed for light section steel from 1.2mm to 4.0mm, such as purlins and rails. TEK® 5 points drill heavy section steel from 4.0mm to 12.0mm, such as structural beams. Using a TEK® 3 in heavy steel will burn the point out before it gets through, so always match the point to the steel thickness. For very heavy sections up to 18mm, choose a SuperTEK® screw.

Question 3

Do I need a sealing washer on my screws?

Accepted Answer

For any external fixing — roof sheeting, wall cladding, composite panels — yes. The bonded EPDM washer compresses under the screw head to seal the drilled hole against water. For internal, dry applications such as framing connections, an unwashered screw is normally fine. Evoshield® washered screws are available with 12mm, 16mm and 19mm diameter washers depending on the load-spreading and sealing required.

Question 4

What length of screw do I need for composite panels?

Accepted Answer

As a rule of thumb, take the panel thickness and add the depth needed to fully penetrate the steel support plus the screw's thread allowance — typically at least 25–30mm beyond the panel. For example, a 100mm composite panel is usually fixed with a 125–135mm fastener. Our Screw Finder at the top of this page will narrow the range down for you, or contact our technical team for a fixing specification.

Question 5

How corrosion-resistant is the Evoshield® coating?

Accepted Answer

Evoshield® is a multi-layer protective coating that is independently salt-spray tested to 500 hours as standard, with 1,000-hour rated options for more demanding environments. It comfortably exceeds the performance of standard zinc plating and is suitable for external building envelope applications. For coastal, marine or highly corrosive environments, consider our Bi-Metal range with A2 or A4 stainless steel heads and bodies.

Question 6

Are Evoshield® screws stocked in Europe?

Accepted Answer

Yes. The core Evoshield® range is held in both our UK warehouse and our Netherlands depot. Use the UK / NL stock toggle above to see exactly what's available from each location, with fast delivery across the UK, Ireland and mainland Europe.

Question 7

What is the difference between EvoShield® 500HR and 1,000HR coatings?

Accepted Answer

EvoShield® 500HR is designed for demanding external applications, while 1,000HR provides a higher level of corrosion protection for more severe exposure conditions. The right choice depends on the project environment and durability requirements.

Evoshield® Self-DrillingTEK® Screws

Where Evoshield® Screws Are Used

Roof & Wall Cladding

Composite & Insulated Panels

Timber to Steel

Metal Framing & Drylining

Frequently asked questions