Hammer-type Anchor – Fixture will be non-removable
The hammer drive and nylon nail-it anchors are two fasteners that fall into the hammer type category. Neither of these anchors results in a stud protruding from the wall. Both of these anchors are basically non-removable. They are simple to use but should only be used in light duty applications because the only diameter available is 1/4″. The hammer drive anchor is produced with a low profile, mushroom head while the nylon nail-it anchor is available in three head styles – mushroom, round and flat countersunk.
Female-type Anchor – Fixture will be removable
There are a number of different female type anchors. The anchor chosen will depend on the type of bolt being inserted into the anchor as well as the quality of the base material. The sizes of these anchors are designated by the inside diameter of the anchor, which is the size of the bolt that will be inserted into it. The different female type anchors and their unique characteristics are listed below:
The machine screw anchor requires a machine threaded bolt with national coarse threads. For example, 1/4″-20 machine screws require a 1/4″ bolt with 20 threads per inch. This anchor also needs to be set in the base material using an appropriately sized setting tool. The 1/4″ and 5/16″ machine screw anchors should be considered for light duty applications and the 3/8″ and 1/2″ for medium duty. The 5/8″ and 3/4″ diameter machine screws are typically reserved for heavy duty use.
Lag shield anchors require the use of a lag screw. Lag shield anchors are available in short and long lengths. The length of the lag shield is generally determined by the quality of the base material. The long lag shield is usually used when the quality of the base material is suspect. The extra length of the long lag shield increases its ability to perform properly. The 1/4″ and 5/16″ lag shield anchors can be used in light duty applications, the 3/8″ and 1/2″ for medium duty and 5/8″ and 3/4″ for heavy duty.
The single expansion anchor and double expansion anchor require the use of a machine threaded fastener with national coarse threading. Both anchors work well in most base materials. The double expansion anchor should be used in applications with questionable base material quality. Both the single and double expansion anchors come in a variety of diameters to allow for usage in many different applications. The 1/4″ and 5/16″ should be used for light duty type loads, the 3/8″ and 1/2″ for medium loads and the 5/8″ and 3/4″ for heavier loading applications.
Leadwood screw anchors were originally made from lead. These concrete anchors are now produced from a material called Zamac – a softer, non-corrosive metal. This fastener is used in light duty applications since it is only available up to 5/16″ in diameter. The leadwood screw anchor requires the use of a sheet metal screw. Like sheet metal screws, these anchors are also designated by the gauge wire used to produce the screw – #6, #8 and so on. Different lengths are available in each diameter and can be used in applications with many embedment requirements.
Concrete Screw- Fixture will be removable
The concrete screw is designed to tap threads into base materials made of concrete, brick or block. They work well in mortar joints as well as in the solid and hollow sections of a block for light duty loads. They are availabe in a wide array of lengths in both 3/16″ and 1/4″ diameters. Two different head styles are available – hex head and flat philips for countersinking.
All of the fasteners described above are suitable for use in concrete block- whether it be the solid section of the block, the hollow section or the mortar joint. These fasteners may be used in light or medium load applications with a non vibratory, non-shock load.
Although some of the fasteners listed above may be appropriate for heavy duty loads, it is not recommended to fasten a heavy load to concrete block. The strength and integrity of the block will be limiting and will most likely fail with a load that is too heavy. Heavy duty, non-vibratory, non-shock loads would require a through-bolted fastening technique or a concrete epoxy type fastener. Vibratory and shock loads would also require a through-bolted fastening system, a concrete epoxy type anchor or a cast-in place fastener. An engineer should always be consulted if your application requires any of these fastening techniques.
Many construction projects and applications will require fastening to concrete block. Before getting started, it is essential to choose the correct type of concrete anchor as well as determine in what part of the block to fasten the load. Taking the time to make the right decisions will ensure safe and effective anchoring. There are anchors available for use in a wide range of applications. Load type will also be a determining factor during the installation of concrete anchors. With the right knowledge, research and a bit of patience, anchoring concrete fasteners to block can be a simple process.
As with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety googles, handle all tools with extra care and follow all technical specifications. This article is meant to serve as a basic overview of how to fasten concrete anchors into block. Always refer to the manufacturers’ instructions or consult a contracting expert during any anchoring project.