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Self Drilling Screws for Light Steel – Bi-Metal
Bi-metal self drilling screws designed for fixing into light section steel up to 5mm, offering high corrosion resistance for demanding environments.
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head – 5.5mm x 70mm – Box of 100
In stock
£42.24 ex VAT(£50.69 inc VAT)
SKU:
BML70
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head with EPDM Washer – 5.5mm x 50mm – Box of 100
In stock
£36.33 ex VAT(£43.59 inc VAT)
SKU:
BML50W16
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head – 5.5mm x 50mm – Box of 100
In stock
£33.33 ex VAT(£39.99 inc VAT)
SKU:
BML50
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head with EPDM Washer – 5.5mm x 38mm – Box of 100
In stock
£35.83 ex VAT(£42.99 inc VAT)
SKU:
BML38W16
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head – 5.5mm x 38mm – Box of 100
In stock
£30.58 ex VAT(£36.69 inc VAT)
SKU:
BML38
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head – 5.5mm x 32mm – Box of 100
In stock
£29.66 ex VAT(£35.59 inc VAT)
SKU:
BML32
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head with EPDM Washer – 5.5mm x 25mm – Box of 100
In stock
£30.58 ex VAT(£36.69 inc VAT)
SKU:
BML25W16
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head – 5.5mm x 25mm – Box of 100
In stock
£26.99 ex VAT(£32.39 inc VAT)
SKU:
BML25
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head with EPDM Washer – 5.5mm x 100mm – Box of 100
In stock
£61.66 ex VAT(£73.99 inc VAT)
SKU:
BML100W16
Timco Self Drilling Screws – Light Steel – Exterior Bi-Metal – Hex Head – 5.5mm x 100mm – Box of 100
In stock
£57.49 ex VAT(£68.99 inc VAT)
SKU:
BML100
These self drilling screws combine a hardened carbon steel drill tip with an A2 stainless steel body. As a result, they deliver fast drilling performance while also providing superior corrosion resistance compared to standard exterior or zinc screws.
This makes them ideal for external applications where durability is critical, such as roofing, cladding and exposed steelwork.
Why choose bi-metal self drilling screws?
- Hardened carbon steel drill tip for fast drilling into steel
- A2 stainless steel body for enhanced corrosion resistance
- Designed for light section steel up to 5mm
- Self-drilling point removes the need for pre-drilling
- Ideal for outdoor and exposed environments
What are bi-metal self drilling screws?
Bi-metal self drilling screws combine two materials to deliver both strength and durability. The hardened carbon steel tip drills through steel efficiently, while the stainless steel body resists corrosion over time. Because of this, they are ideal for applications where both performance and longevity are important.
Where are they used?
Bi-metal self drilling screws for light steel are commonly used for:
- Roofing sheets and cladding
- External metal-to-metal fixing
- Steel structures in exposed environments
- Industrial and commercial construction
- Applications where corrosion resistance is critical
Zinc vs exterior vs bi-metal screws
- Zinc self drilling screws: Best for internal use and dry environments
- Exterior coated screws: Suitable for outdoor use with moderate corrosion resistance
- Bi-metal screws: Provide the highest level of corrosion resistance for demanding environments
Bi-metal screws are the best choice when long-term durability and resistance to corrosion are the priority.
With or without EPDM washer – which should you choose?
| Type | Best For |
|---|---|
| With EPDM Washer | Roofing and cladding applications where a watertight seal is required |
| Without Washer | General metal-to-metal fixing where sealing is not required |
Available Sizes & Options
| Size | Type | Typical Use |
|---|---|---|
| 5.5 x 25mm | Standard / With EPDM Washer | Light metal-to-metal fixing and roofing sheet installation |
| 5.5 x 32mm | Standard | General fixing into light section steel |
| 5.5 x 38mm | Standard / With EPDM Washer | Fixing sheets and brackets to steel |
| 5.5 x 50mm | Standard / With EPDM Washer | Deeper penetration into light steel sections |
| 5.5 x 70mm | Standard | Longer reach fixing where extended penetration is required |
| 5.5 x 100mm | Standard / With EPDM Washer | Long reach fixing through thicker materials into steel |
Standards & Performance
- Bi-metal construction with A2-304 stainless steel body
- Hardened carbon steel drill tip
- Corrosion Rating: 4 (urban and industrial areas with moderate salt exposure)
- Self-Drilling No.3 point
- 60° self-tapping thread
- Fully threaded for strong fixing
Frequently Asked Questions
What are bi-metal self drilling screws used for?
They are used for fixing metal to steel in environments where corrosion resistance and durability are important.
Do these screws need a pilot hole?
No, the self-drilling point allows them to drill and fix in one action.
When should I choose bi-metal over exterior screws?
Choose bi-metal screws when you need higher corrosion resistance, especially in exposed or more demanding environments.
Are these suitable for roofing?
Yes, especially when used with an EPDM washer to create a watertight seal.
