Metal screws are vital components in modern construction, roofing, cladding, framing, and industrial fabrication. Selecting the right metal screw type—based on metal substrate, gauge thickness, head style, drive type, and corrosion resistance—is critical for structural integrity, performance, and longevity.
BDN Fasteners, a Taiwanese manufacturer certified to Australian standard AS 3566, offers a wide array of metal screw types engineered to meet diverse steel‑to‑steel and steel‑to‑timber applications. This guide explores BDN’s product families, technical features, and applications—alongside best‑practice advice for choosing the correct screw.
BDN’s METAL‑Tite™ screws are TEK‑style self‑drilling fasteners designed to drill, tap, and fasten in one operation. Made from high‑strength carbon steel (C‑1022) and available in various coatings, they comply with AS 3566.1 for steel‑to‑steel cladding and structural applications.
Dual‑Edge® (a.k.a. Thunder‑Shot) Drill Point: Enables fast, clean cutting through steel up to ~4.5–6 mm thick (depending on thread type).
No. 5 Drill Point: Used in heavy‑duty models to penetrate up to 12.5 mm thick substrates, ideal for sandwich panels and thick steel cladding.
Engineered for roof and wall cladding on steel purlins up to 6.0 mm thick. Its upper thread has a larger diameter for pull‑out strength; shank knurls to clear swarf and protect washers from damages.
Standard sizes: 12‑14×50mm, 55mm, 65mm, 75mm, 110mm, 130mm.
Sizes normally start from 45mm, and all the way up to 400mm. Suitable where through‑fixing into support is.
Used for valley fixing lightweight cladding to steel purlins up to 4.0mm thick. Sizes include 10‑16×16mm, 19mm, and 25mm.
No.5 drill point heavy duty screws such as 12‑24×32mm, 38mm, 50mm handle sandwich panels or thick steel up to 12.5mm.
Stitching screws are also called reduced point or needle‑point screws, which are mainly used for lap‑fixing light gauge panels. Screws such as reduced point 15‑15×20mm or needle point 10‑16×19mm are commonly used to minimise thread stripping and provide adequate fixing.
Wafer‑head screws are capable of penetrating up to 4.0 mm thick steel panels, and are normally chosen for its low‑profile and aesthetics.
Common sizes: 10‑24×16mm, 10‑24×22mm
These screws are specifically designed for fixing steel trusses to plates/beams (~0.75–1.6 mm thick) using trident drill points and high pull‑out strength.
Frame fixing screws (FRAME‑Tite™) with flat top head, e.g. M6.0×22mm, connect studs or lintels to plate, no pre‑punched holes needed
TIMBER‑Tite™ screws are Type 17 self‑tapping screws optimised for steel‑to‑timber fastening, making them an essential option within the wide range of BDN’s metal screw types. They feature:
They are ideal for cladding over timber battens, purlins, sub-frames or timber-framed structures.
Read more: How to Use Self-Tapping Screws? The Right Way to Install Them）
Polycarbonate roof fasteners (POLY-FAST™, POLYXPAND™) are designed for fixing polycarbonate solid flat, corrugated, or multi-wall hollow sheets to steel or timber substrates:
Self‑drilling screw with built-in 11 mm expansion hole cutter, depth‑stop knurls, domed EPDM washer.
Handles steel substrates up to ~4.5 mm, C4 coating for coastal durability, and saves ~50% labour by combining drilling, thermal expansion hole cutting and sealing in one go.
Similar concept but designed for polycarbonate skylight to timber fixation.
These fasteners also come with Domed EPDM washers, recyclable and non‑conductive seals to prevent galvanic corrosion.
BDN Fasteners offers AS3566.2 compliant coatings to suit different corrosion zones. Coating options include:
All products are ISO 9001:2015 and CE certified. Quality control includes in‑house dimensions and drilling performance inspections, along with tests done by third‑party accredited laboratories such as SGS.
Choosing the right metal screw types is more than just picking a size or head style—it’s about ensuring strength, durability, and long-term performance in your project.
With so many options available, from different substrates to coating requirements, it can be challenging to know which screw is best suited for the job. Here are five key points you should consider before selecting metal screws.
Torsional load strength is a measure of how much torque a screw can withstand before it fails by twisting off or breaking. This property is crucial for ensuring screws can handle the stresses involved in tightening and in their intended application.
Below is a table of the minimum torque for torsional strength of different screw gauges according to AS3566 standards.
| newton metres | |||
| Size designation | Torque | ||
| Type ASD | Type BSD | Type CSD | |
| ST 3.5 (No. 6) | 2.7 | 2.7 | 2.7 |
| ST 4.2 (No. 8) | 4.4 | 4.7 | 5.4 |
| ST 4.8 (No. 10) | 5.4 | 6.9 | 7.3 |
| ST 5.5 (No. 12) | 9.4 | 10.9 | 11.3 |
| ST 6.3 (No. 14) | 14.1 | 16.9 | 17.6 |
The best way to see the benefits of choosing the right fasteners is through real-world examples. In this section, we present case studies that illustrate how proper screw selection leads to stronger connections, smoother installation, and more reliable long-term performance.
Use BDN METAL‑Tite #12 double‑thread screws (e.g. SDHCG1255C3N, SDHCG1265C3N) when fixing metal roof sheeting to steel purlins up to ~6 mm thick. The dual thread gives superior pull‑out strength; shank knurls maintain washer integrity by clearing swarf.
For thick panels (metal‑insulation‑metal), BDN’s No. 5 drill‑point screws (e.g. SDH5F1238C3N, SDH5F1250C3N) can drill through up to 12.5 mm steel and penetrate insulation/core to secure into backing substrate—ideal for industrial warehouses or cold storage systems.
Use POLY‑FAST™ self‑drilling screws with integrated expansion hole cutter and Domed EPDM washer. These screws create an 11 mm hole in sheet, seal around fix, and prevent crack propagation due to thermal movement—all in one pass. Saves up to 50% labour versus drill‑then‑fix approaches.
When metal sheeting fixed to timber battens, use TIMBER‑Tite Type 17 screws sized appropriately (e.g. 10‑12×25mm or 10‑12×20mm) with EPDM washers. Ideal for cladding installations where timber supports are used.
| Screw Series / Type | Intended Use | Head / Drive | Drill Capacity | Steel Thickness |
| METAL‑Tite™ (#10 gauge) | Cladding to metal (valley fixing) | Hex flange / dual‑edge | ~4 mm | 0.75–4 mm |
| METAL‑Tite™ (#12 gauge) | Roof sheeting to metal (crest fixing) | Hex flange / double-thread | ~6 mm | up to ~6 mm |
| METAL‑Tite™ (No. 5 point) | Sandwich panels / thick steel | Hex flange / double-thread | ~12.5 mm | up to ~12.5 mm |
| Stitching screws | Side‑lap panel fix | Reduced or needle point | ~2–3 mm | for light gauge sheets |
| Concealed fasteners | Aesthetic flat cladding | Wafer head / PH2+ | up to ~4 mm | light steel profiles |
| TIMBER‑Tite™ (Type 17) | Metal to timber fastening | Hex / Phillips | Self‑tapping into timber | timber substrate |
| POLY‑FAST Metal / Timber | Polycarbonate roof sheeting | Hex flange + EPDM washer | ~4.5 mm steel | handles thermal expansion |
Proper installation is just as important as selecting the right fastener. Following best practices not only ensures reliable performance but also extends the lifespan of both the screw and the structure it supports.
The guidelines below highlight key considerations that help achieve secure, efficient, and long-lasting installations.
Metal screws are not one‑size‑fits‑all components. Correct application demands selecting the right screw series, gauge, head type, drill‑point, and coating—to suit material thickness, substrate type, exposure, and performance requirements.
BDN Fasteners offers a robust lineup—METAL‑Tite™, TIMBER‑Tite™, POLY‑FAST™, FRAME‑Tite™—all meeting AS 3566, backed by ISO‑certified manufacturing, SGS corrosion testing, and thoughtful innovations such as dual‑thread, trident points, and Eco‑BDN washers.
By understanding these product types and pairing them correctly with project demands, specifiers and contractors can achieve strong, corrosion-resistant, fast installations—ensuring structural integrity, visual quality, and long-term performance.
If you need technical support or have product inquiries, contact BDN Fasteners today to find the right solution for your project.
Read more:
How to Attach Wood to Steel Frame? The Best Methods Explained
What Are the Best Screws for Framing? 10 Key Factors to Consider
What Screws to Use for Metal Studs? 10 Must-Know Selection Tips