Simpson 1/4 x 3-1/2 Countersunk Split-Drive Anchor by Simpson is a one-piece mechanical expansion anchor built for fast, reliable fastening into concrete, grout-filled block, and stone. As the anchor is driven into a pre-drilled hole, the split-type expansion mechanism on the working end compresses and exerts outward force against the walls of the hole, creating a secure mechanical hold without adhesives or additional hardware. The countersunk head sits flush with the surface upon installation, making this anchor a practical choice for attaching wood or light gauge steel to solid base materials in dry, interior, and non-corrosive environments.

Key Features

• One-piece split-drive design with built-in expansion mechanism - eliminates the need for adhesives or secondary components, speeding up installation and reducing labor on the job site
• Compatible with concrete, grout-filled block, and stone - gives contractors flexibility across a range of solid base materials without switching anchor types
• Countersunk head profile - sits flush with the surface after driving, producing a clean, low-profile finish ideal for wood-to-concrete and light gauge steel-to-concrete applications
• Zinc-plated carbon steel construction - provides corrosion resistance appropriate for dry, interior, and non-corrosive environments, helping the anchor maintain holding strength over time in suitable conditions
• Requires a 1/4 in. drill bit for hole preparation - the same-diameter bit and anchor simplify tool selection and help ensure a properly sized hole for consistent expansion performance

Why This Product

• Trusted Simpson engineering for demanding structural work - Simpson Strong-Tie mechanical anchors are specified and relied upon by contractors for optimum performance under demanding structural applications, giving buyers confidence in the anchor's holding capability
• Simple, tool-driven installation with no mixing or curing - the split-drive expansion mechanism activates as the anchor is driven into the hole, meaning no adhesive, no wait time, and a faster path from drilling to finished fastening
• Flush countersunk head keeps surfaces clean and functional - ideal for applications where a protruding fastener head would interfere with attached materials or finished surfaces, such as wood framing or light gauge steel channels anchored to a concrete slab
• Consistent hole sizing simplifies procurement - because the drill bit diameter matches the anchor diameter at 1/4 in., contractors need only one bit size to prepare holes, reducing the chance of mismatched tooling on site

Specifications

• Manufacturer: Simpson Strong-Tie
• MPN: CSD25312
• Diameter: 1/4 in.
• Length: 3-1/2 in.
• Head Type: Countersunk Head
• Head Diameter: 1/2 in.
• Drill Bit Diameter: 1/4 in.
• Material: Carbon Steel
• Coating/Finish: Zinc Plated
• Packaging: Packs of 100 and Cartons of 400

Approved Applications

• Concrete base material
• Grout-filled block (grouted CMU)
• Stone
• Attaching wood to concrete or grout-filled block surfaces
• Attaching light gauge steel to concrete or grout-filled block surfaces
• Dry, interior, and non-corrosive environments only

Frequently Asked Questions

What base materials can the Simpson CSD25312 Split-Drive Anchor be installed in?

The CSD25312 can be installed in concrete, grout-filled block, and stone. It is not intended for use in hollow CMU or other unsupported base materials.

What drill bit size is required for installation?

A 1/4 in. diameter drill bit is required to prepare the hole before driving the CSD25312 anchor into the base material.

Is the CSD25312 suitable for outdoor or corrosive environments?

No. The CSD25312 is designed for use in dry, interior, and non-corrosive environments only. Its zinc-plated carbon steel construction is not rated for wet, exterior, or chemically corrosive conditions.

How does the split-drive expansion mechanism work?

As the anchor is driven into the pre-drilled hole, the split-type expansion mechanism on the working end compresses and exerts outward force against the walls of the hole, creating a secure mechanical hold within the base material.

Note: Product dimensions may differ from picture. Please see the item description above for specifications.