The Simpson CNW5/8 Coupler Nut with Witness Hole from Simpson is engineered to connect threaded rods to one another and to anchor bolts in structural applications. Designed to exceed the specified minimum tensile capacity of the corresponding bolts and threaded rod, this 5/8 in. coupler nut delivers a reliable, verifiable connection through two purpose-built features: a positive stop for consistent thread engagement and a Witness hole for visual confirmation of proper rod installation. Available in a Zinc Plated or Uncoated finish, the CNW5/8 is a trusted hardware component for contractors and builders who need dependable rod-to-rod connections.

Key Features

• Witness hole for visual installation verification - tighten the two rods until each all-thread rod is visible in the Witness hole, so you can confirm correct engagement at a glance without guesswork.
• Positive stop feature - helps ensure proper thread engagement into each end of the nut, giving you consistent, balanced rod seating on both sides of the coupler every time.
• Exceeds specified minimum tensile capacity - these coupler nuts are designed to exceed the specified minimum tensile capacity of the corresponding bolts and threaded rod, supporting the structural integrity of the connection.
• For non-hot-dip galvanized all-thread rod only - clearly defined compatibility keeps your assembly within tested and verified parameters, reducing the risk of mismatched hardware in the field.
• 5/8 in. rod diameter with a minimum height of 1 1/2 in. - purpose-sized dimensions ensure a secure fit on standard 5/8 in. threaded rod and anchor bolt applications.

Why This Product

• Built-in verification means no second-guessing - the Witness hole lets installers visually confirm that both threaded rods are fully seated before finalizing the connection, reducing costly installation errors on the job site.
• Engineered for structural confidence - by exceeding the specified minimum tensile capacity of corresponding bolts and threaded rod, this coupler nut is suited for load-bearing rod extension and anchor bolt connections where performance margins matter.
• Consistent results through smart mechanical design - the positive stop eliminates uneven threading by guiding each rod to the correct depth, making installation more predictable across repetitive structural tie applications.
• Flexible finish options for your project environment - the choice between Zinc Plated or Uncoated finish allows you to match the coupler nut to your specific coating and corrosion-protection requirements.

Specifications

• Manufacturer: Simpson Strong-Tie
• MPN: CNW5/8
• Bolt/Rod Diameter: 5/8 in.
• Height (min.): 1-1/2 in.
• Coating: Zinc Plated or Uncoated
• Finish: Zinc Plated or Uncoated

Options

• Available in standard strength and high strength depending on corresponding rod in use
• Couplers available with oversized threads on one end for installation on hot-dip galvanized bolts (See OST models for ordering)
• OST couplers are typically oversized on one end of the coupler nut only and will be marked with an "O" on oversized side

Frequently Asked Questions

How do I know when the threaded rods are properly installed in the CNW5/8 coupler nut?

The CNW5/8 features a Witness hole that allows you to visually verify proper rod installation. Tighten the two rods until each all-thread rod is visible through the Witness hole, confirming that both rods are fully and correctly engaged.

What is the purpose of the positive stop feature on the CNW5/8?

The positive stop feature helps ensure even and proper thread engagement into each end of the nut. It acts as a built-in guide so that each threaded rod is inserted to the correct depth on both sides of the coupler.

Can the CNW5/8 coupler nut be used with hot-dip galvanized all-thread rod?

No. The CNW5/8 is designed for non-hot-dip galvanized all-thread rod only. For use with hot-dip galvanized bolts, refer to the OST model variants, which feature oversized threads on one end to accommodate the thicker galvanized coating.

What rod diameter is compatible with the Simpson CNW5/8 coupler nut?

The CNW5/8 coupler nut is specifically designed for a 5/8 in. rod diameter, with a minimum height of 1-1/2 in., and is available in a Zinc Plated or Uncoated finish.

Note: Product dimensions and/or screw or bolt holes may differ from picture. Please see item description for specifications.