The Simpson Adhesive Retaining Cap for 1/2 in. Anchor Rod and #4 Rebar is a plastic anchor accessory from Simpson engineered to keep anchoring adhesive contained inside a drilled hole during rod or rebar dowel insertion. Designed specifically for overhead, upwardly inclined, horizontal, and deep-embedment applications where adhesive runout or off-center placement can compromise results, this retaining cap holds adhesive in position while simultaneously centering the insert in the hole - giving installers greater control over adhesive coverage and anchor alignment from the moment of insertion through full cure.

Key Features

• Slit design allows the insert to pass through while containing the adhesive in the hole - keeps anchoring adhesive from running out during rod or rebar insertion, helping ensure consistent adhesive coverage and full embedment without wasted material or messy cleanup.
• Centers the threaded rod or rebar dowel during insertion into the drilled hole - reduces the chance of off-axis placement, making this cap especially useful where precise anchor positioning is required by the project design.
• Designed for overhead, upwardly inclined, and horizontal orientations as well as deep embedments - addresses the most demanding installation conditions where gravity and hole geometry would otherwise cause adhesive loss or inconsistent fill.
• Compatible with any Simpson anchoring adhesive - works across the full range of Simpson Strong-Tie anchoring adhesive products, so installers are not locked into a single adhesive system when using these caps.
• May be used with the Simpson Strong-Tie Piston Plug Delivery System - integrates with an established adhesive delivery method, supporting efficient, controlled dispensing in production or repetitive-anchor workflows.

Why This Product

• Solves the core problem of overhead and horizontal adhesive anchor installations - adhesive containment is the single biggest challenge when anchoring into overhead or side-wall holes, and this cap directly addresses that by sealing the hole opening while still allowing rod or rebar insertion.
• Improves placement accuracy without extra effort - the centering function is built into the cap itself, so installers automatically achieve better-centered anchors on every hole without additional tools or adjustments, which matters most in applications requiring precise anchor layout.
• Broad application versatility from one accessory - because the cap handles overhead, inclined, horizontal, and deep-embedment conditions and works with any Simpson anchoring adhesive, a single product covers the range of challenging orientations a crew is likely to encounter on a given job.
• Backed by a trusted structural connector and anchor brand - Simpson is a widely recognized name in structural fastening and anchoring systems, and this cap is purpose-built to complement the adhesive anchor products in that same lineup, supporting a consistent, coordinated installation system.

Specifications

• Manufacturer Part Number (MPN): ARC50-RP25
• Brand: Simpson Strong-Tie
• Hole Diameter: 5/8 in.
• Drill Bit Diameter: 5/8 in.
• Bolt/Rod Diameter: 1/2 in. / #4 rebar
• Material: Plastic
• Packaging: Packs of 25 and Cartons of 200
• Country of Origin: United States

Approved Applications

• Overhead adhesive anchor installations where adhesive containment is required
• Horizontal adhesive anchor installations
• Upwardly inclined anchor orientations
• Deep embedment applications requiring precise anchor placement
• Applications using the Simpson Strong-Tie Piston Plug Delivery System
• Installations with 1/2 in. threaded rod anchors or #4 rebar dowels

Frequently Asked Questions

What is the purpose of the slit in the Simpson ARC50 adhesive retaining cap?

The slit in the cap is specifically designed to allow the threaded rod or rebar dowel to pass through during insertion while simultaneously containing the anchoring adhesive inside the drilled hole. This ensures the adhesive stays in place rather than running out, which is especially important in overhead and horizontal installations.

Can the ARC50 retaining cap support the weight of the anchor during overhead installations?

No. Adhesive retaining caps are not designed to support the weight of the anchor. In overhead installations, it is advisable to provide an adequate means of anchor support during the adhesive cure time to ensure a safe and proper installation.

Which anchoring adhesives are compatible with the Simpson ARC50-RP25 retaining cap?

The ARC50-RP25 works with any Simpson Strong-Tie anchoring adhesive, offering broad compatibility across the Simpson Strong-Tie adhesive anchor product line. It may also be used in conjunction with the Simpson Strong-Tie Piston Plug Delivery System.

What anchor and hole sizes is the ARC50-RP25 designed to fit?

The ARC50-RP25 is designed for use with a 5/8 in. drilled hole diameter (requiring a 5/8 in. drill bit) and is sized for a 1/2 in. threaded rod anchor or a #4 rebar dowel. The cap centers the rod or rebar within the hole to ensure precise anchor placement.

Note: Adhesive retaining caps are not designed to support the weight of the anchor in overhead installations. In overhead applications, provide an adequate means of anchor support during cure time.