A wedge anchor is a type of fastener designed to be installed into solid concrete.
Types
Wedge anchors are manufactured out of different materials and plated differently for added rust resistance. The standard materials from which wedge anchors are manufactured are carbon steel, 303, 304 or 316 stainless steel. The carbon steel is plated with a zinc plating, hot-dipped galvanized or mechanically galvanized.
Description
The wedge anchor is described in two parts, with the first number describing the diameter of the wedge anchor and the second number notating its length. For example, the description of a 5/8” diameter wedge anchor that is 8-1/2” long would be 5/8” x 8-1/2”.
Diameters
Wedge anchors are available in nine diameters: 1/4”, 5/16”, 3/8”, 1/2”, 5/8”, 3/4”, 7/8”, 1” and 1-1/4”. Not all companies carry the full range of diameters. For example, Hilti, Inc does not have a 5/16” or a 7/8” kwik-bolt wedge anchor. However, Concrete Fastening Systems, Inc. has all diameters in all materials available in stock.
The diameter of wedge anchor chosen is based on the holding values required and the hole diameter in the item being fastened.
Lengths
Each diameter of wedge anchor comes in different lengths ranging from 1-3/4” length in the 1/4” diameter to 12” lengths in the 1/2”, 5/8”, 3/4”, 7/8”, 1” and 1-1/4” diameterss. Adding the minimum embedment for the diameter of wedge anchor being used plus the thickness of the material, plus space for the nut and washer determines the minimum length of wedge anchor used for any particular application.
Spacing
As a rule of thumb, wedge anchors need to be spaced a minimum of 10 anchor diameters from each other. For example, a 1/2” wedge anchor needs to be at a minimum of 5” from each other.
Edge Distance
Wedge anchors need to be placed no closer than 5 anchor diameters to an unsupported edge of concrete as a minimum. For example, the 1/2” diameter wedge anchor should be minimally 2-1/2” close to an unsupported edge from which it is installed.
Hole Size
The diameter of the hole that is drilled into the concrete is equal to the diameter of wedge anchor being installed; a 3/4” diameter wedge anchor requires a 3/4” hole.
Hole in Fixture
If the wedge anchor is going to be inserted through the fixture and into the concrete with the fixture in place, then the hole in the fixture needs to be larger than the designated diameter of the wedge anchor being installed. Below is a chart showing the diameter of hole required for each diameter of wedge anchor. The fixture is referred to as the item that is being fastened to the concrete with the wedge anchor.
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Wedge Anchor Diameter
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Hole in Fixture
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1/4”
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5/16”
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5/16”
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3/8”
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3/8”
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1/2”
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1/2”
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5/8”
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5/8”
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3/4”
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3/4”
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7/8”
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7/8”
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1”
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1”
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1-1/4”
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1-1/4”
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1-3/8”
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Drilling Concrete
Drilling a hole in concrete for a wedge anchor must be done using a hammer drill set in the hammer and rotation mode. Hole size and shape are critical to obtaining holding values when installing wedge anchors. The only way to insure this is through the use of a hammer drill.
Bit
The bit that must be used in the hammer drill must be carbide tipped and meet ANSI standards. The ANSI standard carbide bit will insure proper tolerance between hole diameter and wedge anchor and diameter.
Manufacturers
Concrete Fastening Systems, Inc. has a complete line of wedge anchors in all diameters, material types and plating.
For more information, click on the links below:
Purchase Wedge Anchors
Technical Information
Please remember with all fastening jobs to keep safety in mind. Always follow safety instructions on all tools, and refer to manufacturer's installation instructions when available and always remember to wear safety goggles!
Article written by: Michael Pistorino, Concrete Fastener Specialist