Simpson 4-inch 20d Annular Ring Shank Common Nail in Type 316 Stainless Steel is a heavy-duty fastener engineered for demanding wood-framing and wood-to-wood fastening applications where corrosion resistance and superior holding strength are essential. Featuring a full round head, diamond point, and an annular ring shank that dramatically increases withdrawal resistance compared to smooth-shank nails, this 6-gauge nail delivers a secure, long-lasting connection in exterior environments - including coastal and seaside conditions where saltwater exposure can degrade lesser materials. Type 316 stainless steel provides an elevated level of corrosion resistance, making these nails an outstanding choice for permanent wood foundations, outdoor structures, and high-moisture job sites.

Key Features

• Annular ring shank design - increases withdrawal resistance compared to smooth-shank nails, creating a stronger mechanical grip in wood framing and structural connections that resists backing out over time.
• Type 316 stainless steel material and finish - offers superior corrosion resistance in saltwater, chemical-rich, and harsh outdoor environments, making these nails ideal for seaside and coastal construction.
• 4-inch length / 20d penny size - provides the depth of penetration needed for solid wood-to-wood and structural framing connections in standard and heavy lumber applications.
• 7/16-inch full round head - distributes clamping force across a wider surface area for a more secure, reliable hold without tearing through the wood face.
• Diamond point tip - allows easier starting and driving into hardwood and dense lumber, reducing splitting and improving placement accuracy.
• 6 gauge / 0.203-inch shank diameter - a heavy-gauge shank adds shear strength, supporting structural connections in wood framing where lateral loads are a concern.
• Made in the United States - domestically produced to consistent quality standards for professional construction and building applications.

Why This Product

• Built for coastal and high-moisture environments: Type 316 stainless steel is the preferred material for seaside construction, where standard galvanized or lesser stainless fasteners can corrode and fail. These nails hold up where the conditions are harshest.
• Annular ring shank solves the pull-out problem: In framing and structural wood connections, fastener withdrawal is a real failure point. The annular ring shank mechanically locks into wood fibers, resisting pull-out forces that can compromise a connection over time.
• Sized for real framing work: At 4 inches and 20d, with a 0.203-inch shank diameter and full round head, this nail is built for the demands of wood framing - not a lightweight or finish application. It delivers the penetration depth and shear strength professional framing jobs require.
• Trusted Simpson Strong-Tie quality: Simpson Strong-Tie has a long-standing reputation for engineered fastening solutions. These exterior nails are part of a fastener line designed to match the performance and longevity expected from structural hardware.

Specifications

• Brand: Simpson Strong-Tie
• Material: Type 316 Stainless Steel
• Finish: Type 316 Stainless Steel
• Gauge: 6
• Length: 4 in.
• Penny Size: 20d
• Shank Diameter: 0.203 in.
• Shank Type: Annular-Ring Shank
• Head Diameter: 7/16 in.
• Head Type: Full Round Head
• Point Type: Diamond Point
• Approx. Count per Lb.: 25
• Country of Origin: United States

Available Pack Options

• T20ACN1: 1 Lb (25)
• T20ACN5: 5 Lb (125)
• T20ACNB: 25 Lb (625)

Approved Applications

• Fastening Wood-to-Wood
• Framing - Wood

Frequently Asked Questions

What makes Type 316 stainless steel better than Type 304 for outdoor nailing applications?

Type 316 stainless steel contains molybdenum, which gives it superior resistance to chlorides and saltwater compared to Type 304. This makes Type 316 the preferred choice for seaside, coastal, and other high-moisture or chemically aggressive environments where long-term corrosion resistance is critical.

Why choose an annular ring shank nail over a smooth-shank nail for wood framing?

The annular ring shank features rings along the shank that mechanically interlock with wood fibers as the nail is driven. This significantly increases withdrawal resistance compared to a smooth shank, meaning the nail resists backing out or pulling free under load - an important advantage in structural framing and wood-to-wood connections.

What does the diamond point on these nails do?

The diamond point is a four-sided tapered tip that allows the nail to start and drive more cleanly into wood, including denser lumber. It helps reduce splitting in the wood and improves the accuracy of nail placement, especially when working close to board edges.

Are these nails appropriate for permanent wood foundation construction?

Stainless steel nails are recommended by the ANSI/AWC Permanent Wood Foundation Design Specifications for construction of permanent wood foundations. Type 316 stainless steel, in particular, is recommended for applications requiring superior corrosion resistance, including seaside locations and environments with prolonged moisture exposure.