Simpson #14 x 3-1/4" Self-Drilling Flat-Head Screw with Wing in 410 Stainless Steel is engineered for fastening wood, plywood, and fiber cement panels directly to steel framing - delivering a clean, flush finish with the structural integrity required in demanding construction applications. The wing-tip design and drill-point geometry eliminate the need for pre-drilling, making this fastener a reliable choice for exterior cladding, structural sheathing, and fiber cement siding installation over steel substrates up to 0.209" thick. Built from Type 410 stainless steel with added corrosion protection coating, this screw is designed for jobsites where durability and performance matter.

Key Features

• Type 410 stainless steel with corrosion protection coating - heat-treatable alloy allows the screw to drill through steel while the coating adds a layer of corrosion resistance, extending service life in outdoor and moisture-exposed installations.
• Drill point with wings (Point Size 4) - wings bore a clearance hole through wood or fiber cement so the workpiece does not climb up the shank, then break off cleanly when the point contacts the steel substrate, resulting in a tight, professional fit without spinning or cracking the panel.
• Flat countersunk head with self-countersinking nibs - seats flush with the surface automatically, eliminating the need for a separate countersinking step and producing a clean, finished appearance on fiber cement and plywood panels.
• #3 square drive (compatible with replacement bit model BIT3S-2-R2) - provides high torque transfer with minimal cam-out, reducing stripped drive recesses and keeping installation fast and consistent.
• Machine screw thread, threaded full length, 20 TPI - full-length threading into the steel substrate maximizes pull-out and shear strength, ensuring panels stay securely anchored over time.
• Shank slot design - enhances thread formation in steel and channels exhaust away from the hole, improving drilling efficiency and reducing heat buildup in the screw tip.
• Max grip length of 3.100" - accommodates a wide range of combined material thicknesses, giving installers flexibility across different panel and framing configurations.
• #14 diameter, 3-1/4" length - heavy-duty sizing for secure fastening in applications where smaller screws may lack the clamping force needed for fiber cement or thicker plywood assemblies.

Why This Product

• Eliminates pre-drilling in wood-to-steel assemblies - the self-drilling wing point bores its own clearance hole through wood and fiber cement before engaging the steel, saving significant time on the jobsite compared to two-step drilling and fastening methods.
• Purpose-built for fiber cement and plywood over steel - the wing-tip clearance mechanism prevents the common problem of panels climbing the shank and cracking or lifting, which is especially critical with brittle fiber cement siding materials.
• Stainless steel construction with heat-treatment capability - Type 410 stainless is specifically hardened to drill through metal, a capability that standard stainless screws lack, making this the correct fastener when both corrosion resistance and metal-drilling performance are required.
• Flush, finished installation with no additional tools - the self-countersinking flat head with nibs sets itself into the panel surface in a single driving step, reducing labor and producing a clean result ready for painting or finishing.

Specifications

• Brand: Simpson Strong-Tie
• Screw Size: #14
• Length: 3-1/4 in.
• Head Type: Flat Head
• Head Diameter: 0.470 in.
• Drive Type: #3 Square
• Shank Type: Shank Slot
• Thread Type: Machine Threads
• Thread Length: Full
• TPI: 20
• Max Grip Length: 3.100 in.
• Point Type: Drill Point with Wings
• Point Size: 4
• Material: Type 410 Stainless Steel
• Country of Origin: Taiwan

Available Pack Options

• F14C325FDC: 100 Pk
• F14C325FDB: 1000 Pk

Approved Applications

• Securing wood and plywood to steel framing up to 0.209" thick
• Attaching fiber cement siding and panels to steel studs or framing
• Exterior sheathing installation where flush fastener heads are required
• Applications requiring corrosion-resistant fasteners in outdoor or moisture-prone environments

Frequently Asked Questions

What is the maximum steel thickness this screw can drill through?

This screw is designed to self-drill into steel substrates up to 0.209" thick. For steel thicker than this, a different fastener or pre-drilling may be required to ensure proper engagement and pull-out performance.

How do the wings on the point work, and when do they break off?

The wings above the drill point bore a clearance hole through the wood or fiber cement workpiece as the screw is driven. This prevents the panel from climbing up the shank during installation. When the point contacts the steel substrate, the wings break off cleanly, allowing the machine threads to engage and pull the panel tight against the steel.

Why is Type 410 stainless steel used for a self-drilling screw instead of Type 316?

Type 410 stainless steel can be hardened through heat treatment, which gives it the hardness needed to drill through metal substrates. Type 316 stainless steel, while offering superior corrosion resistance, cannot achieve the same hardness and is therefore not suitable for self-drilling applications into steel. The additional corrosion protection coating on this screw helps supplement the corrosion resistance of the Type 410 alloy.

What replacement driver bit is compatible with the #3 square drive on this screw?

The #3 square drive on this screw is compatible with the Simpson replacement bit model BIT3S-2-R2, which is available separately and recommended for consistent, high-torque driving with minimal cam-out.

Note: Product dimensions and/or thread length may differ from picture.