A quick overview of the types of concrete wedge anchors, the correct depth to drill, and steps for installation.
Different types of concrete wedge anchors are manufactured for use in different applications. The only differences between the types of concrete wedge anchors are the material that they are made from and the plating or coating that is used for improving the corrosive resistance of the steel. 12mm Flange Nut
Rule of Thumb: The larger the diameter, the better the holding value.
Concrete wedge anchors are made from a single bar of steel that is threaded on one end, and the other end is necked down with a permanently attached clip. They are packaged with the correct-sized nut and washer and come in nine different diameters ranging from 1/4 in. to 1-1/4 in. Each diameter of concrete wedge anchor is available in different lengths from 1-3/4 in. in the 1/4 in. diameter to 12-in. long in all diameters larger than 1/2 in.
Read about anchor bolt tolerances at ForConstructionPros.com/12281002.
The diameter of concrete wedge anchor to use for any particular application depends on the weight of the object being fastened, on the diameter of the hole size in the object being fastened, and on any specifications of diameter recommended by an engineer. The rule of thumb is that the larger the diameter than the better the holding values. Concrete Fastening Systems Inc. provides a table for holding values and technical specifications for wedge anchors online.
The length of concrete wedge anchor to use is based on the thickness of the material being fastened plus the embedment depth of the concrete wedge anchor into the concrete. Each diameter of a concrete wedge anchor has a minimum embedment depth that the anchor must be inserted into the concrete for it to obtain minimum holding values. Adding the minimum embedment of the diameter of concrete wedge anchor being used to the thickness of the material being fastened plus the thickness of the nut and washer will give the minimum length of concrete wedge anchor that should be used.
The diameter of the hole to drill for a concrete wedge anchor is equal to the diameter of the concrete wedge anchor being installed. A 5/8” concrete wedge anchor requires a 5/8” hole to be drilled into the concrete.
The hole in the concrete needs to be drilled a minimum of 1/2” deeper than the concrete wedge anchor will penetrate into the concrete. This extra space is required to make sure that the concrete wedge anchor does not bottom out in the hole before reaching the intended embedment depth, and also allows for any dust that may be created during the installation to fall out of the way.
12mm Expansion Bolt Bob Carlisle has been president of Concrete Fastening Systems, Inc. for 29 years, and has been involved in the concrete anchor business since 1981.