What are Wedge Anchors?
Wedge anchors, also called concrete stud anchors and wedge bolts, are mechanical expansion anchors used to fasten into solid, cured concrete (often called “cement” in searches). They’re frequently chosen for concrete slabs, walls, and filled masonry. Use sleeve or toggle anchors unless the hollow blocks have been completely filled solid with grout.
What parts are in a wedge anchor assembly
- Threaded anchor body with a tapered section at the tip
- Expansion clip (wedge) that locks against the hole wall during tightening
- Flat washer sized to the anchor diameter
- Hex nut used to draw the clip into expansion and clamp the fixture
The washer and nut are included with most wedge anchors so the assembly is ready to install.
Why use wedge anchors in concrete and block
- High, consistent load capacity in solid concrete and filled masonry
- Fast installation with standard carbide masonry bits and hand tools
- Clean hardware stack above the surface for plates, rails, and brackets
- Broad diameter and length range to match fixture thickness and embedment needs
Where are concrete wedge anchor fasteners used regularly
- Base plates, post and sign supports, guardrails, and safety barriers
- Equipment pads, racks, machines, and material handling
- Pipe supports, strut framing, electrical and HVAC mounts
- Structural steel connections where drawings specify wedge anchors
Types of wedge anchors
- Zinc plated carbon steel for dry interior conditions
- Hot dip galvanized for outdoor or wet exposure
- 304 stainless steel for general corrosion resistance
- 316 stainless steel for coastal and chemical environments
How wedge anchors work
The anchor is driven into a drilled hole in concrete. Tightening the nut pulls the anchor body upward so the expansion clip rides the taper and wedges firmly against the hole wall, creating friction and mechanical interlock that resist pull-out and shear.
How to install wedge anchors in concrete
- Drill the hole
- Use a carbide tipped bit that matches the anchor diameter; drill perpendicular to the surface.
- Drill deeper than the minimum embedment so dust has room at the tip.
- Clean the hole
- Brush and blow out dust with a wire brush and compressed air or vacuum to ensure full expansion.
- Insert the wedge anchor
- Thread the nut a few turns to protect the threads, then tap the anchor until the washer and nut seat on the fixture.
- Expand the anchor
- Snug the nut to draw the clip into expansion so the anchor grips the concrete.
- Tighten the nut
- Use a wrench to reach the recommended torque for the anchor size.
Tips for successful installation
- Wear proper PPE; install only in sound, cured concrete
- Maintain required spacing and edge distance to prevent cracking or breakout
- Avoid under- or over-tightening; verify torque after set
Choosing wedge anchors for your project
Which length should the anchor be
- Concrete thickness at the install point
- Fixture thickness plus nut and washer thickness
- Minimum embedment for the chosen diameter
- Any extra clearance you prefer
Total Anchor Length = Minimum Embedment Depth + Fixture Thickness + Nut Thickness + Additional Clearance
Minimum Embedment Depth For Wedge Anchors
| Diameter | 1/4" | 5/16" | 3/8" | 1/2" | 5/8" | 3/4" | 7/8" | 1" | 1-1/4" |
| Minimum Embedment Depth | 1-1/8" | 1-1/8" | 1-1/2" | 2-1/4" | 2-3/4" | 3-1/4" | 3-7/8" | 4-1/2" | 5-1/2" |
Which material is best for your purpose
- 316 stainless for coastal or chemical exposure
- 304 stainless or hot dip galvanized for exterior and wet areas
- Zinc plated for dry interior spaces
What size wedge anchor do I need (inch and metric)
- Select diameter by load and fixture hole (1/4 in, 3/8 in, 1/2 in, 5/8 in, 3/4 in; M8, M10, M12)
- Length equals required embedment plus fixture and hardware stack
- Follow edge distance and spacing rules for full capacity
Troubleshooting and common issues
- Insufficient embedment reduces strength
- Over-tightening can crush concrete or damage hardware
- Under-tightening may allow movement and loss of preload
- Wrong hole size prevents proper expansion
- Near edges or weak concrete may cause cracking; respect distances
- Poor hole cleaning leaves dust that limits holding power
- Incorrect material choice can lead to corrosion or staining
Sleeve anchor vs wedge anchor
- Sleeve anchors work across more substrates (including some hollow block)
- Wedge anchors typically deliver higher shear and tensile values in solid concrete
- Choose sleeve for versatility; choose wedge for strength in concrete
FAQs about Wedge Anchors
Key answers for selection, sizing, installation, and materials in concrete, “cement,” and filled block.
- Do wedge anchors work in concrete, cement, and block?
They are intended for solid, cured concrete (often searched as “cement”) and filled masonry. For hollow block, use sleeve or toggling anchors unless the cell is fully grouted.
- What drill bit size should I use?
Use a carbide tipped bit equal to the anchor diameter unless the product specifies otherwise.
- How deep should the hole be?
Deeper than the minimum embedment so dust has room at the tip. Follow the embedment requirement for your anchor size.
- What parts come with a wedge anchor?
Threaded anchor body, expansion clip, flat washer, and hex nut.
- Can wedge anchors be removed and reused?
They can be removed but are not reusable once set. If removal is needed, unthread the nut and drive the anchor flush or out.
- Do wedge anchors work in cracked concrete?
Some models are qualified for cracked concrete. Verify the rating and follow the installation instructions.
- Which finish should I choose for outdoor use?
Hot dip galvanized for most exterior work; 304 or 316 stainless where corrosion exposure is high, with 316 preferred near saltwater.
- Why is hole cleaning important?
Dust left in the hole can reduce expansion and holding power. Brush and blow the hole clean before setting the anchor.
- What if the hole is oversized?
Do not install the wedge anchor. Drill a new hole to the correct diameter for proper expansion and capacity.