Simpson Fiber-Cement Screw in #8 x 1-1/4", Type 316 Stainless Steel is purpose-built for attaching fiber-cement siding to stressed-skin panels and securing lap siding to wood framing. Engineered by Simpson Strong-Tie for demanding exterior applications, this fastener combines a wafer head with self-countersinking nibs, a Type-17 point for effortless driving, and full-length coarse threading - delivering a reliable, flush-seating connection in fiber-cement and composite siding work. The Type 316 stainless steel construction resists corrosion in coastal, high-moisture, and chemically aggressive environments where standard steel fasteners would fail.

Key Features

• Wafer head with self-countersinking nibs - seats flush against fiber-cement surfaces without pre-drilling a countersink, saving installation time and reducing surface damage
• Type-17 point - bores into fiber-cement and wood quickly for fast starts, reducing splitting and improving drive-in efficiency
• Full-length coarse threading - maximizes grip in fiber-cement siding and wood substrates for a secure, pull-resistant hold
• Type 316 stainless steel material and finish - provides superior corrosion resistance in saltwater exposure, coastal climates, and wet outdoor conditions where standard zinc-coated fasteners are insufficient
• #2 square drive - reduces cam-out compared to Phillips drive, improving torque transfer and lowering the chance of stripped heads during installation
• #8 screw size, 1-1/4" length - sized specifically for fastening fiber-cement siding to stressed-skin panels with proper penetration depth
• 0.395" head diameter - wide bearing surface distributes load across the siding face, helping prevent pull-through in fiber-cement panels

Why This Product

• Designed specifically for fiber-cement siding applications - the self-countersinking wafer head and Type-17 point work together to seat cleanly in fiber-cement without causing surface cracking or requiring additional prep steps
• Type 316 stainless steel goes beyond standard corrosion resistance - it withstands chloride exposure and harsh outdoor environments, making it the right choice for coastal or high-humidity siding projects where fastener failure is a long-term concern
• The coarse full-length thread pattern ensures maximum holding power when attaching fiber-cement siding to wood framing or stressed-skin panels, reducing the risk of fastener loosening over time
• The #2 square drive reduces slippage and cam-out during high-volume siding installation, helping installers work faster and with more consistent results on every board

Specifications

• Brand: Simpson Strong-Tie
• Screw Size: #8
• Length: 1-1/4 in.
• Head Type: Wafer Head
• Head Diameter: 0.395 in.
• Drive Type: #2 Square
• Thread Type: Coarse Threads
• Point Type: Type-17 Point
• Material: Type 316 Stainless Steel
• Finish: Type 316 Stainless Steel
• Country of Origin: Taiwan

Available Pack Options

• T08C125WQC: 100 Pk
• T08C125WQM: 1000 Pk

Approved Applications

• Underlayment / Backer board
• Fastening Fiber-Cement Siding

Frequently Asked Questions

What makes this screw suitable for fiber-cement siding?

This screw features a wafer head with self-countersinking nibs that seats flush against fiber-cement without cracking it, a Type-17 point for fast, clean starts, and full-length coarse threading for a secure grip in both fiber-cement panels and wood substrates. These features work together to make it a dedicated fastener for this application rather than a general-purpose screw.

Why is Type 316 stainless steel used for this fastener?

Type 316 stainless steel offers a higher level of corrosion resistance than standard stainless grades, particularly in environments with chloride exposure such as coastal areas, high-humidity conditions, or locations subject to moisture contact. For exterior siding applications where fasteners are exposed to the elements long-term, this material helps maintain structural integrity over time.

What substrate is the 1-1/4" length designed to fasten into?

According to the product data, the 1-1/4" length is intended for attaching fiber-cement siding to stressed-skin panels. This length provides the appropriate penetration depth for that specific substrate combination.

What drive bit does this screw require?

This screw uses a #2 square drive bit. The square drive design helps reduce cam-out during installation, which is especially useful when driving multiple fasteners in fiber-cement siding work where consistent torque is important.

Note: Product dimensions and/or thread length may differ from picture. Please see the item description above for specifications.