
Hex Washer Head Self-Drilling Screw with EPDM Washer
DIN 7504K indented hex washer head roofing screw with bonded EPDM washer, ST4.2–ST6.3, drill points #1–#5.

Galvanised hex flange head Tek screw with integral serrated flange, for steel-to-steel framing and cladding.
The integral flange works as a built-in washer, so the head bears on a wide area without a loose part. It is the go-to screw for steel framing, cable trays and racking where a seal is not needed.
Available plain or with an EPDM sealing washer, in class 4.8 and 6.8 equivalent hardness, with metric or inch threads.
Typical values. Every dimension, hardness and coating is confirmed in writing with your quotation.
| Diameter | ST3.5–ST6.3, #6–#14 |
|---|---|
| Length | 13–150 mm |
| Material | Carbon steel, stainless steel |
| Head | Hex flange, indented, optional serrations |
| Drill point | #2–#5 |
| Finish | Zinc, blue-white zinc, black oxide, ceramic |
| Certificate | ISO 9001 |
| MOQ | 5,000 pcs |
| HS code | 7318.14 / 7318.12 (by type) |
Applies to all self-drilling screws.
Point #1 suits sheet up to 0.9 mm, #2 up to 2.8 mm, #3 up to 4.4 mm, #4 up to 5.25 mm and #5 up to 12.5 mm. The drill flute must clear the full material thickness before the thread engages, or the screw will jam and snap.
Roofing and cladding screws take a bonded EPDM washer (14, 16 or 19 mm) under an indented hex washer head. The rubber seals the hole; the steel backing spreads the load so the sheet does not dimple.
Electro-zinc gives roughly 72 h to white rust in salt spray. For exterior roofing ask for ceramic coating (500–1,000 h) or AS 3566 Class 3/4 coatings, and for coastal sites move to bi-metal stainless screws.
Standard terms for this product. Tell us if your market needs something different.
A self-tapping screw forms threads in a pre-drilled hole, while a self-drilling screw drills its own hole first using a drill-shaped point. Self-drilling screws save a step on metal-to-metal joints.
We produce to DIN 7504 (K, M, N, P, O forms), ISO 15480–15483 and AS 3566.1/.2, and to customer drawings for non-standard lengths, heads or head marks.
Standard sizes start at about 500 kg or 50,000 pieces per size. Mixed sizes can share one container, and stock items can ship in smaller lots.
Tell us the screw, size and quantity. A sales engineer replies within one business day with price, lead time and a sample offer.