BIS Certified · EPDM Washer · Metal Bonded Washer · Hex Flange Head · ISO 15480
The DIN 7504 K hex head self drilling screw is the most widely used fastener in metal roofing, pre-engineered buildings and steel framing across India. The "K" designation in DIN 7504 K specifies a hexagonal washer head — a six-sided drive head with a built-in stamped steel flange that distributes clamping load over a wider area than a plain hex head. Combined with a self drilling point, it eliminates the need for a pilot hole entirely — drilling, tapping and fastening in one single operation. The equivalent international standard is ISO 15480. All DIN 7504 K screws stocked by Excel Trading Corporation are BIS certified and fully compliant with the Quality Control Order applicable in India.
Metal roofing sheet to steel purlin — with EPDM or metal bonded washer
Pre-engineered building (PEB) cladding and structural connections
External wall cladding panels to steel secondary structure
Industrial shed and warehouse roofing
Solar panel mounting frame to steel structure
General metal-to-metal fastening in medium and heavy duty applications
No pilot hole required — drills, taps and fastens in one single operation
Precision ground cutting edges for fast drilling with minimum effort
Point-to-thread design maximises pull-out strength and minimises backout
Integrated hex washer head flange distributes load and prevents pull-through
Available zinc plated and ruspert coated for superior corrosion resistance
BIS certified — IS compliant, QCO approved for sale in India
Zinc
Stainless Steel
All sizes available in zinc plated and ruspert coated finish. Drill Point #2 penetrates up to 2.0mm steel; Drill Point #3 penetrates up to 4.0mm steel — suitable for roofing sheet to purlin connections on standard PEB and industrial structures.
| Size | Length (inch) | Length (mm) | Drill Point (m/m) | Drill Capacity (m/m) |
|---|---|---|---|---|
| #10-16 M4.8 | 3/4” | 19 | #2 | 1.0 - 2.0 |
| 1” | 25 | #3 | 1.0 - 3.0 | |
| #12-14 M5.5 | 3/4” | 19 | #3 | 2.0 - 4.0 |
| 1” | 25 | #3 | 2.0 - 4.0 | |
| 1-1/4" | 32 | #3 | 2.0 - 4.0 | |
| 1-1/2" | 38 | #3 | 2.0 - 4.0 | |
| 2" | 50 | #3 | 2.0 - 4.0 | |
| 2-1/2" | 63 | #3 | 2.0 - 4.0 | |
| 3" | 75 | #3 | 2.0 - 4.0 | |
| 14-14 M6.3 | 3/4” | 19 | #3 | 2.0 - 4.0 |
| 1” | 25 | #3 | 2.0 - 4.0 | |
| 1-1/4" | 32 | #3 | 2.0 - 4.0 | |
| 1-1/2" | 38 | #3 | 2.0 - 4.0 | |
| 2" | 50 | #3 | 2.0 - 4.0 | |
| 2-1/2" | 63 | #3 | 2.0 - 4.0 | |
| 3" | 75 | #3 | 2.0 - 4.0 | |
| 4" | 100 | #3 | 2.0 - 4.0 | |
| 5" | 125 | #3 | 2.0 - 4.0 |
The DIN 7504 K hex head self drilling screw is available in three washer configurations — each suited to a different application. Choosing the correct washer type is as important as choosing the correct screw size. The wrong washer leads to water ingress, seal failure and costly remediation on roofing projects.
A metal bonded washer consists of a steel outer ring with EPDM or neoprene rubber permanently vulcanised into the centre. Unlike a loose EPDM washer, the rubber cannot spin, slip or detach during installation — a common failure mode with loose washers driven at high speed.
The steel outer ring provides significantly higher clamping load and load distribution than a standalone rubber washer. This makes it the preferred choice for industrial roofing, heavy gauge cladding sheets, high-vibration environments such as industrial sheds near machinery, and large-span PEB structures where long-term seal integrity under wind-induced movement is critical.
The bonded construction also means the washer remains centred and sealed even if the screw is slightly overtightened — the steel ring limits compression and prevents the rubber from being crushed out.
Washer construction: Steel ring + bonded EPDM/neoprene insert
Key advantage: No spinning, no slippage, higher clamp load
Temperature range: −40°C to +120°C
Material: Carbon steel — ruspert or hot dip galvanised
Diameters: M5.5 (12-14), M6.3 (14-14)
Standard: DIN 7504 K / ISO 15480
Standard choice for metal roofing & outdoor cladding
The most widely used DIN 7504 K variant in India for metal roofing. An EPDM (Ethylene Propylene Diene Monomer) rubber washer is factory-bonded to a steel backing plate and assembled under the hex head. When driven, the EPDM compresses against the roofing sheet surface to create a watertight seal around the drilled hole.
EPDM is the correct material for outdoor roofing in India — it is highly resistant to UV radiation, ozone, monsoon humidity and temperature cycling from −40°C to +120°C. Standard neoprene or plain rubber washers deteriorate within 2–3 years under these conditions and must never be substituted for EPDM on outdoor roofing.
Used for standard metal roofing sheet to purlin connections, external wall cladding, pre-engineered building envelopes and any outdoor application requiring a weather seal at the fastening point.
Washer type: EPDM bonded to steel backing plate
Washer OD: 16mm (standard) / 19mm (large)
UV & ozone resistance: Excellent — suitable for outdoor use
Temperature range: −40°C to +120°C
Material: Carbon steel — zinc plated or ruspert coated
Diameters: M4.8, M5.5, M6.3
Standard: DIN 7504 K / ISO 15480
Maximum pull-through resistance for thin sheets
The hex flange head is a further development of the standard DIN 7504 K screw. Instead of a stamped collar, the flange is a larger forged steel disc integrated directly into the head — providing a significantly larger bearing area than a standard hex washer head without any separate backing washer.
When combined with an EPDM or metal bonded washer placed under the enlarged flange, this becomes the highest performing DIN 7504 K variant — delivering maximum pull-through resistance, the largest possible seal footprint and the best wind uplift resistance available in a hex head self drilling screw.
Use hex flange head screws when fixing thin or soft roofing sheet profiles where pull-through is a structural risk, on large span roofing with high wind uplift loads, in coastal Bangalore and Karnataka locations where the largest seal area reduces long-term water ingress risk, and on PEB projects requiring certified pull-out force values.
Flange OD (typical): 20mm to 24mm
Available with: EPDM washer / metal bonded washer
Drive: Hex socket — 8mm or 10mm
Material: Carbon steel — zinc plated or ruspert coated
Diameters: M5.5, M6.3
Standard: DIN 7504 K / ISO 15480
| Feature | Plain Hex Head | + EPDM Washer | + Metal Bonded Washer | Hex Flange + Washer |
|---|---|---|---|---|
| Weather Seal | None | Excellent | Excellent | Superior |
| Washer Stability During Install | — | Good | Superior — bonded | Superior — bonded |
| Pull-Through Resistance | Standard | Good | Good | Maximum |
| Clamp Load | Standard | Good | High | Maximum |
| UV & Ozone Resistance | — | Excellent | Excellent | Excellent |
| Best For | Indoor / dry use | Standard metal roofing | Industrial / high vibration | Heavy PEB / coastal / thin sheet |
| DIN Standard | DIN 7504 K | DIN 7504 K | DIN 7504 K | DIN 7504 K |
DIN 7504 K specifies a hexagonal washer head self drilling screw with an integrated stamped steel flange under the head. It drills, taps and fastens in one operation with no pilot hole. The international equivalent is ISO 15480. It is the most common fastener for metal roofing, cladding and steel framing in India and globally.
An EPDM washer is a rubber disc bonded to a steel backing plate — it compresses under the head to seal the fastening point and is ideal for standard metal roofing. A metal bonded washer has EPDM permanently vulcanised inside a steel outer ring, preventing the washer from spinning or shifting during installation and providing higher clamping load. Choose metal bonded for heavy industrial roofing, high-vibration environments and large-span PEB structures.
Use a hex flange head when fixing thin or soft roofing sheets where pull-through is a risk, on large span roofing with high wind uplift, or in coastal areas where the largest possible seal area is needed. When fitted with an EPDM or metal bonded washer under the enlarged flange, it provides the maximum combination of pull-through resistance and weather sealing in a self drilling screw.
Yes. Under the BIS Quality Control Order, all self drilling screws sold in India must carry the BIS Standard Mark. Using non-certified screws is a violation of the BIS Act 2016. Excel Trading Corporation stocks only BIS certified DIN 7504 K screws — fully compliant with Indian law.
We stock DIN 7504 K hex head self drilling screws in M4.8 (#10-16), M5.5 (#12-14) and M6.3 (14-14) diameters. Lengths range from 19mm (3/4") to 125mm (5"). Available in zinc plated and ruspert coated finish with EPDM washer, metal bonded washer or plain hex head options. Call us on +91-9448239476 for pricing and availability.
A plain hex head DIN 7504 K screw without a washer provides no weather seal at the fastening point — water will enter through the drilled hole over time, causing corrosion and leakage. For any outdoor roofing or cladding application, always specify DIN 7504 K with EPDM washer as the minimum. For industrial and coastal locations, use a metal bonded washer for long-term seal integrity.
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