Wedge Anchors. Selection and Installation

Wedge anchors are one of the most common mechanical fasteners for anchoring into solid concrete. They provide a strong, permanent connection and are widely used in structural, commercial, and industrial applications. This guide covers how wedge anchors work, how to choose the right size and material for your project, and how to install them correctly. Use the reference tables below to find drill bit sizes, embedment depths, and installation torque values for every standard wedge anchor diameter.

In This Guide:

• How Does a Wedge Anchor Work?
• Choosing the Right Wedge Anchor
• Installation Data by Diameter
• Step-by-Step Installation
• Common Installation Mistakes
• Materials and Finishes
• Common Applications
• Frequently Asked Questions

How Does a Wedge Anchor Work?

A wedge anchor consists of a threaded bolt body with an expansion clip (wedge) at the base. The anchor is inserted into a hole drilled in solid concrete, and as the nut is tightened, the bolt is drawn upward while the clip remains in place. This pulls the tapered end of the bolt through the clip, forcing it outward against the walls of the hole. The resulting friction and mechanical interlock creates a secure hold in the concrete.

Because the holding force depends on this expansion mechanism, wedge anchors are designed for use in solid concrete and are considered a permanent anchoring solution. Once set, a wedge anchor cannot be removed and reused. If you need a removable concrete fastener, consider a screw anchor instead.

Choosing the Right Wedge Anchor

Selecting the correct wedge anchor involves matching four factors to your application: diameter, length, material, and load requirements.

Diameter

Wedge anchors are available in standard fractional diameters from 1/4" through 1". The diameter you need depends on the load the anchor must carry and the size of the holes in the fixture being attached. Larger diameters provide higher tension and shear capacity but require thicker concrete and greater edge distances.

• 1/4" to 3/8" — Light duty: electrical panels, conduit, small brackets, cable trays
• 1/2" to 5/8" — Medium duty: equipment pads, HVAC units, handrails, racking systems
• 3/4" to 1" — Heavy duty: structural base plates, crane rails, seismic bracing, heavy equipment

Length

The overall length of a wedge anchor must account for three measurements added together: the thickness of the material being fastened (the fixture, base plate, bracket, etc.), plus the minimum embedment depth into the concrete, plus enough thread above the surface for the nut and washer. A common rule of thumb is to embed at least 4 to 6 bolt diameters into the concrete. For example, a 1/2" diameter anchor should embed at least 2" to 3" into the concrete. Always check the manufacturer’s minimum embedment requirements — they vary by diameter and are listed in the installation data table below.

Load Requirements

Every wedge anchor has published tension (pullout) and shear (lateral) load capacities. These values depend on the anchor diameter, embedment depth, concrete strength, and whether the concrete is cracked or uncracked. For applications where the anchor will experience both tension and shear simultaneously, the loads must be combined using an interaction equation. Always consult the manufacturer’s load tables and engineering data for your specific installation.

For seismic applications, use anchors that are qualified for seismic design categories A through F, such as the Simpson Strong-Tie Strong-Bolt 2 (ICC-ES ESR-3037).

Wedge Anchor Installation Data by Diameter

The table below provides the key installation specifications for standard wedge anchors across all common diameters. Use this as a quick reference when selecting your drill bit, determining hole depth, and setting your torque wrench.

*Minimum embedment depths shown are general guidelines. Always verify against the specific manufacturer’s requirements for your anchor. Values shown above are representative of carbon steel anchors in concrete. Stainless steel torque values may differ.

Drill Bit Quick Reference

The drill bit diameter for a wedge anchor always matches the nominal anchor diameter. Use a carbide-tipped drill bit rated for concrete. An SDS-plus or SDS-max rotary hammer drill bit is recommended for best results, especially in harder concrete and larger diameters.

How to Install a Wedge Anchor

Follow these steps for a proper wedge anchor installation. The same general process applies regardless of diameter or manufacturer.

Step 1: Drill the Hole

Using a carbide-tipped drill bit that matches the anchor diameter (see the table above), drill a hole into the solid concrete. The hole depth must be at least as deep as the minimum embedment depth listed for your anchor size. Tip: Drill the hole 1/2" deeper than the minimum embedment depth to leave space for concrete dust at the bottom of the hole.

Step 2: Clean the Hole

Blow the hole clean using compressed air to remove concrete dust and debris. For non-overhead installations, use a nylon hole-cleaning brush to loosen dust from the walls before blowing it out. Dust left in the hole can prevent the anchor from reaching full depth and will reduce its holding capacity. Overhead installations do not need to be blown clean, as gravity will help clear loose material.

Step 3: Assemble and Insert the Anchor

Thread the nut onto the anchor so the top of the nut is flush with the top of the bolt. This protects the threads during installation. Place the washer under the nut. Position the anchor through the hole in the fixture (base plate, bracket, angle, etc.) and into the drilled hole. Drive the anchor into the hole using a hammer until the washer and nut are snug against the fixture surface.

Step 4: Tighten to Required Torque

Using a torque wrench set to the specified installation torque (see the installation data table), tighten the nut. As the nut turns, the bolt body is drawn upward through the expansion clip, forcing the clip outward against the concrete. Once the specified torque is reached, the anchor is fully set.

Common Wedge Anchor Installation Mistakes

Most wedge anchor failures in the field are caused by installation errors, not product defects. Avoid these common mistakes:

Oversized Holes

If the drilled hole is even slightly larger than the anchor diameter, the expansion clip cannot grip the concrete properly. This happens when a worn drill bit is used or when the installer drills at an angle, widening the hole. Always use a sharp, properly sized carbide bit and drill straight into the concrete.

Insufficient Hole Depth

If the hole is not deep enough, the anchor cannot reach the required embedment depth. The expansion clip will sit too high in the hole, reducing pullout strength. Always measure your required embedment depth before drilling, and add an extra 1/2" for dust clearance at the bottom.

Dirty Holes

Concrete dust left in the hole acts as a lubricant that prevents the expansion clip from gripping. Blow the hole clean with compressed air after drilling. On critical installations, use a nylon brush followed by compressed air for best results.

Installing in Cracked or Weak Concrete

Standard wedge anchors are designed for solid concrete with a minimum compressive strength of 2,500 psi. If the concrete has visible cracks at the anchor location, use an anchor that is code-listed for cracked concrete. The Simpson Strong-Tie Strong-Bolt 2 is tested per ACI 355.2 for both cracked and uncracked concrete (ICC-ES ESR-3037). Do not install wedge anchors in brick, block, or hollow masonry without grout fill.

Insufficient Edge Distance

Installing too close to the edge of a concrete slab or wall can cause the concrete to break out under load. Every anchor diameter has a minimum edge distance and a critical edge distance. As a general rule, maintain at least 5 anchor diameters from any free edge and 10 anchor diameters between adjacent anchors. Consult the anchor manufacturer’s data for exact values.

Using an Impact Wrench

Impact wrenches deliver torque in short, high-energy bursts that can damage the expansion mechanism, mushroom the threads, or crack the surrounding concrete. Always hand-tighten with a calibrated torque wrench to the values shown in the installation data table.

Wedge Anchor Materials and Finishes

Wedge anchors are available in several material and coating options. The right choice depends on the environment, exposure, and any applicable code requirements.

For more detail on fastener materials and corrosion resistance, see our Fastener Materials and Coatings Guide.

Common Wedge Anchor Applications

Wedge Anchor vs. Other Concrete Anchors

Wedge anchors are one of several concrete anchor types. The right choice depends on whether the installation is permanent or temporary, the base material, and the load.

Browse all options in our Anchor Bolts & Concrete Anchors category.

Frequently Asked Questions

What size drill bit do I need for a wedge anchor?

The drill bit diameter is the same as the wedge anchor diameter. A 1/2" wedge anchor requires a 1/2" carbide-tipped concrete drill bit. Use an SDS-plus or SDS-max rotary hammer drill for best results. See the drill bit chart above for recommendations by size.

Can I use wedge anchors in block or brick?

Standard wedge anchors are not recommended for hollow block or brick. They are designed for solid concrete. For block or brick, use a sleeve anchor or a screw anchor, both of which are tested for masonry substrates. Wedge anchors can be used in grout-filled concrete masonry units (CMU) — check the manufacturer’s load tables for masonry-specific ratings.

Can wedge anchors be removed and reused?

No. Wedge anchors are permanent fasteners. Once the expansion clip is set, it cannot be retracted. You can remove the nut to release the fixture, but the clip stays embedded in the concrete. If you need a removable anchor, use a concrete screw anchor instead.

What is the minimum concrete thickness for wedge anchors?

Minimum concrete thickness varies by diameter. For a 1/2" wedge anchor, the minimum is approximately 4". For a 3/4" anchor, approximately 6". See the installation data table for exact values by diameter.

What is the difference between a wedge anchor and a sleeve anchor?

Both are expansion anchors, but they use different mechanisms. A wedge anchor has a solid bolt body with a small clip at the bottom — it provides higher load capacity but only works in solid concrete. A sleeve anchor has an expandable sleeve around the full length — it provides lower load capacity but works in concrete, block, and brick. See the comparison table above.

Are wedge anchors approved for seismic zones?

Yes, but not all wedge anchors carry seismic qualifications. Look for anchors tested per ACI 355.2 and qualified for seismic design categories A through F. The Simpson Strong-Tie Strong-Bolt 2 carries ICC-ES ESR-3037 and is qualified for static and seismic loading in both cracked and uncracked concrete. Eugene Fastener stocks seismic-rated wedge anchors in multiple diameters — contact Sales@eugenefast.com for availability.

How much weight can a wedge anchor hold?

Load capacity depends on diameter, embedment depth, concrete strength, and whether the concrete is cracked or uncracked. As an example, a single 1/2" carbon steel wedge anchor at standard embedment in 2,500 psi uncracked concrete has an ultimate tensile capacity of approximately 5,200 lbs and an ultimate shear capacity of approximately 7,200 lbs. Always apply appropriate safety factors when calculating working loads. Consult the manufacturer’s engineering data for design-level calculations.

Related Resources

• Fastener Materials and Coatings Guide — Carbon steel, stainless, zinc, HDG, and more
• Anchor Bolts & Concrete Anchors — Shop all concrete anchor types
• Wedge Anchors — Browse in-stock wedge anchors by size and material
• Technical Resource Center — All guides and reference articles

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