What is an Anchor?
Anytime you need to attach a fixture to a wall or even solid concrete, an anchor is essential to provide the stability and strength that is needed. Choosing the right type of anchor is important to ensure proper performance. Not only do you need to choose the type of anchor, but it’s also necessary to consider the size and application of how the anchor will be used.
There are many different types of anchors available, depending on the type of project and application:
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From light duty to heavy duty
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Some are self-drilling, while others require a pre-drilled hole
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Anchors that use a separate screw
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Anchors that are complete and pre-assembled
The more you learn about anchors, the better prepared you are to choose the ideal product for your needs. In this article, we are going to cover essential information that can help you choose the ideal anchors, including why anchors are important, how they work, and why anchors are so valuable in hardware.
How to Choose the Right Anchor Size
When choosing an anchor, several important factors will help you determine the ideal size:
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Base materials that will hold the anchor
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Material dimensions being anchored to the base
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Cost of the anchor and other materials
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Load level and type of load
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Installation requirements to place the anchor
Each situation is unique, which is why there isn’t a one-size-fits-all solution for every project.
How Anchors Work
An anchor is a seemingly small but effective element that links structural and non-structural items. This step is quick and easy but has an undeniable impact to improve the integrity of the construction.
When placing an anchor, the diameter of the drilled hole is slightly smaller than the diameter of the screw. This difference gives the anchor something to hold onto when it is placed.
Certain design factors can improve the strength and integrity of the anchor, such as adhesive bonding, threading, clamping, wedging friction, and self-threading. The anchors can be expanded into the location either through mechanical expanding or manual expanding.
Things To Consider When Choosing an Anchor
Various types of anchor bolts are also available to help with your build. In the next section, we will outline the various designs for anchor bolts. As you are making your selection, it’s important to consider different factors that will affect the performance of the anchor bolt, including fastener length, hole size, concrete thickness, weight of fastening, structural integrity, concrete pounds per square inch (PSI), anchor bolt positioning, professional assistance, and more.
What Are The Different Types of Anchor Bolts?
What type of anchor bolts are ideal for your needs? Consider these factors when comparing the different designs:
L-SHAPED ANCHOR BOLTS
The name describes the overall appearance and layout: L-shaped anchor bolts have a 90-degree angle and look like the letter “L.” These bolts are used in a variety of applications including light poles, sign structures, heavy equipment, and tooling.
DOUBLE-END RODS WITH PLATE ANCHOR BOLTS
This next design includes rods at both ends, with a plate washer added to one end. Depending on the design, the plate can either be welded to the anchor bolt itself or can be tack welded to a nut entrenched in concrete. This design is used primarily in constructing columns for buildings, highway signs, and other applications.
HEADED ANCHOR BOLTS
The feature that makes this anchor bolt design unique is that on the unthreaded end of the anchor bolt is a forged head (usually a hex, heavy hex, or square head). When anchor bolts are needed for different types of construction, then a headed design can be beneficial for embedding into the concrete to hold things like structural columns, bridge railings, and light poles.
SWEDGE ANCHOR BOLTS
If an anchor bolt is “swedged,” then it means that one end has multiple indentations so the concrete can flow in to hold the anchor in place. The design consists of round bar steel that is threaded on one end and “swedged” on the other. These anchors can also be made of other materials, such as stainless steel. Usually, swedge anchor bolts are 100% domestic since they are used for connecting piers and girders.
What Are The Common Types Of Anchors?
Understanding the common types of anchors can be helpful because you not only know the ideal application for each anchor, but you can also see the importance of the placement of these anchors in the project.
There are seven main categories that anchors fall into:
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Internally Threaded
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Externally Threaded
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Masonry Screw and Pin
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Screw
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Hollow Wall
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Sleeve
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Drive Anchors
Internally Threaded
Internally threaded anchors are often used with your machine screws, cap screws, or threaded rod. They are designed to be used with concrete, block, brick, and stone. Keep in mind that a setting tool might be required. Also, these anchors are not removable or reusable, so you need to be sure of the application before placing the anchor.
Drop-In Anchors
Drop-in anchors are commonly known as red-head multi-set drop-in anchors or multipurpose expansion anchors. They are most often used when anchoring concrete and require a setting tool to drive the cone so it can expand the anchor inside the hole. Choose an anchor with lips if you need the mount to be flush with the material's surface. If you want it to be below the surface, then select an anchor without a lip. These anchors are often used with cap screws, threaded rods, and other machine screw threaded fasteners. Or, shell-type anchors can be used for overhead anchoring.
Machine Screw Anchors
Machine Screw Anchors are also known as Calk-In Anchors. They are designed with a pre-assembled threaded expander cone inside, as well as a lead alloy caulking sleeve. These anchors are commonly used in concrete, block, brick, and stone. Since they are short in length, they are ideal for use in shallow holes, but can’t be used for overhead applications.
Double Expansion Shields
There are several common names for Double Expansion Shields, including Machine Bolt Double Expansion Shields and Two-Way Expansion Anchors. This dual expansion system is commonly used in solid concrete, block, brick, and stone. When the screw or bolt is tightened, the internal machine screw threads and expands. This anchor shouldn’t be used for overhead applications.
Single Expansion Shields
Other names for Single Expansion Shields include Machine Bolt Single Expansion Shields or Single Expansion Anchors. These anchors are popular for dual expansion systems and they are commonly used in concrete, block, brick, and stone. The design has a threaded expander cone inside, as well as a set of expansion shields. When the screw is tightened, it causes the wedge-shaped cone to expand the shields inside of the hole. It can be used with cap screws and other machine screw threaded fasteners, but shouldn’t be used in overhead applications.
Externally Threaded
Externally Threaded anchors are made for concrete anchoring and are designed with an exposed threaded stud. The benefit is that a setting is not necessary. But keep in mind that this type of anchor is not designed to be removed or reused.
Chemical Anchors
Chemical Anchors are sometimes known as Chemical Capsule Anchors or Chisel Stud Assembly. There is a chemical capsule inside that contains a "synthetic mortar" that bonds the machine screw threaded stud to the concrete. The most common uses include lightweight and soft masonry substrates. Since the anchor uses chemical bonding, it resists loosening from shock and vibration. One benefit is that no stress is created because there is no requirement for setting or other forms of expansion.
Stud Anchors B
Also known as Red Head Stud Anchors, these anchors are common in concrete applications. They are designed with a bolt body and an expander end plug. To use this anchor, they require a pre-drilled hole sized the same diameter as the anchor. When the anchor is hammered, it causes the expander plug to expand the anchor, which eliminates torquing requirements. This design is common for leveling and jacking applications.
Wedge Anchors A
Wedge Anchors are often used for concrete. The design is heavy-duty and includes machine screw threading. You will need a pre-drilled hole cut to the same diameter as the anchor. When the nut is tightened, it results in a tapered expansion end that expands the anchor.
Wedge Anchors B
Wedge Anchors B are also known as Red Head Wedge Anchors. They are often used for concrete applications and come in diameters ranging from 1/4" to 1 1/4." These anchors are heavy-duty, but they are not bottom bearing. So it can be used in hole depths greater than the length of the anchor.
Wedge Anchors C
The third type of Wedge Anchor is also often used for concrete. These Wedge Anchors are fully assembled and require a pre-drilled hole with the same diameter as the anchor. One of the unique features of this anchor is that it minimizes vibration-induced wedge loosening.
Concrete/ Masonry Screw and Pin Anchors
One-piece anchors are commonly used for concrete, brick, and block. When you have Concrete/Masonry Screws, you will need a pre-drilled hole and these screws are removable. On the other hand, pins do not require a hole and are considered permanent because they cannot be removed.
Concrete/Masonry Screws (Tapcon)
Also known as Tapcon Masonry Screws or Concrete Screws, these screws are often used as fasteners in concrete, brick, and block. The masonry anchor cuts its own threads in a pre-drilled pilot hole. It’s essential to use a Condrive tool which is sold separately. They are available in Slotted Hex Washer and Phillips Flat heads.
Drive Pins
Drive pins, sometimes known as Hammer Drive Pins, are commonly used for light-duty, static load applications. If holding strength is not an important factor, then you might consider these pins. They permanently attach fixtures to concrete and other types of concrete blocks. You don’t need a powder-actuated tool – a standard hand tool is sufficient for installation.
Drive Pins/ Powder Actuated
These pins are also known as Ramset Pins or Ramset Drive Pins. They are often used to permanently attach a fixture to concrete or structural steel. You can choose from different shank lengths, as well as designs with and without a washer. The benefit of the washer is that it increases the bearing surface area against the material you are fastening. The pin has a plastic flute located near the point, which retains and guides the pin during installation.
Screw Anchors
Screw anchors expand when another screw is installed, such as a sheet metal screw, wood screw, or lag screw. They are light-duty anchors often used in concrete, brick, block, stone, mortar joints, wallboard, wood, ceramic tile, and stucco.
Lag Screw Shields
Also known as Long Lag Expansion Shields, Short Lag Expansion Shields, or Lag Screw Anchors, Lag Screw Shields are designed for concrete and the mortar joints of block and brick. The shields are not internally threaded, so you will need to use lag screws. Reduce drilling time in harder masonry using a short style. Or, a long style is a better strength for soft or weak masonry.
Ribbed Plastic Anchors
Ribbed Plastic Anchors are also known as Polysets, commonly used for light-duty applications, including concrete, hollow block and brick, solid brick, and wallboard applications. When you tighten a wood or sheet metal screw, it expands the anchor to grip the wall.
Conical Plastic Anchors
Also known as Plastic Screw Anchors, Conical Plastic Anchors are commonly used for lightweight anchoring in concrete, hollow block and brick, solid brick, and wallboard applications. It is designed with fins on the ridged body, which prevents the anchors from turning during installation.
Tubular Plastic Anchors
Also known as Plastic Plug Screw Anchors or Plastic Plugs, Tubular Plastic Anchors are often used in concrete, block, brick, and stone. This light-duty anchor is ideally used with sheet metal and wood screws. When the screw is installed, then the anchor expands. These anchors are not for overhead usage.
Plug Anchors
Plug Anchors are often used for solid concrete and solid concrete blocks, and are also suitable for brick and drywall. These plugs are generally used with a screw, to help secure the screw in place when the screw can't hold within the material on its own. Plug anchors are often made from plastic or a stronger plastic known as nylon. A drill is required to create a pilot hole, then the blog is placed in the hole and the screw is fastened into the plug anchor using a screwdriver or screw gun. Mungo plug anchors are a trusted brand preferred by many contractors.
Plastic Toggles
Also known as Rawl Long Poly Toggles, Rawl Medium Poly Toggles, or Rawl Short Poly Toggles, Plastic Toggles are often designed for paneling, wallboard, and solid masonry. The application must be screw actuated. If plastic toggles are installed in solid base materials, then it’s necessary to break off the outer wings.
Hollow Wall Anchors
Hollow Wall Anchors are rated for light to medium to heavy-duty loads, and they have either screw or spring actuated tabs, wings or body, or a gravity-operated plate. The design expands behind the wall to lock the anchor in place. Most require a pre-drilled hole, but some are self-drilling.
Hollow Wall Anchors
There are various types of Hollow Wall Anchors, including Drill Style Hollow Wall Anchors, Molly (TAnchors, and Molly Bolts Drive Style Hollow Wall Anchors. These anchors are commonly used for mounting fixtures to hollow walls such as drywall and wood paneling. They offer superior holding power compared to nails and screws. When using these anchors, the prongs under the flange pierce the mounting surface, preventing anchor rotation as the screw is tightened. Inside the wall, metal strips flare to securely lock the anchor in place.
Self Drilling Wallboard Anchors
E-Z Anchor Self-Drilling Drywall Anchors, also known as One Step Wallboard Anchors, are popular for their convenience and ease of use. These anchors are designed for 3/8", 1/2", and 5/8" gypsum wallboards. They are one-step, one-piece anchors that eliminate the need for pre-drilling. Available in metal and nylon versions, they feature a tri-cut point that drills a small hole as the anchor is driven into the wallboard. A notable advantage is that E-Z Ancor Self-Drilling Drywall Anchors are removable, providing flexibility for future changes or replacements.
T-Anchors
Hollow Wall Anchors, also referred to as "T" style anchors, are widely used for their gravity-operated design. The anchor itself features a distinctive "T" shape, with the "T" bar positioned to fit through a hole in the hollow wall. Once inserted, the anchor is rotated until the "T" bar flips, securely locking the anchor in place. This mechanism provides reliable support and stability for fixtures mounted on hollow walls, making the hollow wall anchors a popular choice in construction and DIY projects.
Strap Toggles
Toggler Toggle Bolt Anchors, Strap Toggles, also called Never-Drop Toggle Anchors, are versatile anchors suitable for a wide range of hollow wall applications. They can be used in various surfaces such as hollow brick, hollow and concrete block, cement and gypsum board, drywall, plaster, and paneling.
Unlike traditional toggle bolts, Toggler Toggle Bolt Anchors are installed without a screw. The wall is clamped securely between the wing inside the wall and a cap outside the wall, connected by durable straps. Furthermore, these anchors require a smaller hole size compared to comparable toggle bolts.
Toggle Bolts
Toggle Bolts, also known as Slotted Mushroom Head Toggle Bolts or Slotted Round Head Toggle Bolts, are popular for their applications in hollow walls such as drywall and concrete blocks. These anchors are two-piece assemblies consisting of a machine screw and a spring wing toggle. During installation, the wings are folded back and inserted through a pre-drilled hole in the wall. Once inside the wall and clear of the entrance hole, the spring action causes the wings to open, providing a secure hold.
Toggle Wings
Toggle Wings, also referred to as Spring Toggle Wings, are commonly used in conjunction with round and mushroom-head toggle bolts. If the original toggle wings supplied with the toggle bolts are misplaced or lost within the wall, the Spring Toggle Wings can be used as replacements. Additionally, if there is a desire to select a different type or size of screw for the anchor, these wings provide the flexibility to do so. Toggle Wings are designed to provide secure and reliable support for fixtures mounted in hollow wall applications.
Alligator Anchors (Toggler)
Alligator Anchors, also known as Toggler Alligator Solid/Hollow Wall Nylon Anchors, are versatile anchors suitable for a wide range of materials. These general-purpose anchors can be used in concrete, wood, plaster, masonry, stone, ceramic tile, stucco, and drywall. When installing an Alligator Anchor, a lag, wood, or sheet metal screw is used. As the screw is tightened, it expands and compresses the anchor, causing it to conform to the surface of the hole. This ensures a secure and reliable hold in the chosen material.
Sleeve Anchor
Sleeve Anchors, known by various names such as Acorn Nut Sleeve Anchors, Flat Head Sleeve Anchors, Hex Nut Sleeve Anchors, Round Head Sleeve Anchors, One Step Anchors, or Bolt Anchors, are widely used in concrete and masonry applications. These anchors require a pre-drilled hole that matches the diameter of the anchor. As the nut or screw is tightened, an internal expander activates, causing the expansion sleeve to expand and tightly grip the hole.
Drive Anchor
Drive anchors are sturdy and dependable fasteners designed to offer excellent security and resistance against tampering. With their distinctive design, these anchors utilize a pin to expand after being placed in the desired position. Widely used in construction projects, such as concrete, block, brick, and stone installations, they meet specific requirements for stability and durability.
Drive Pin Rivets (Masonry)
Drive Pin Rivets, also known as Masonry Pin Grip Drive Rivets or Masonry Rivets, are commonly used for fastening into masonry and brick blocks, offering a convenient solution without the need for special installation tools. These rivets are designed to be tamper-resistant, providing added security. When driving the pin flush with the rivet head, the prongs of the rivet expand inside the masonry, creating a robust riveted joint.
Hammer Drive Anchors
Hammer Drive Anchors, also referred to as Hammer Drive Nail-In Anchors, Drive Nail Anchors, or Nail-Ins, are commonly used for permanent mounting applications in concrete, block, brick, and stone. These anchors are designed for light-duty applications and provide tamper-resistant fastening. To install a Hammer Drive Anchor, the center pin is driven flush, which expands the body of the anchor and securely locks it in place.
Fastening Base Materials & Anchor Finishes
Fastening base materials need to be considered when choosing the ideal anchor for a project. The base materials might include solid concrete, solid brick, hollow brick, stone, tile, drywall, plaster, plywood, and hollow concrete block. Not only do many contractors consider the design of the anchor, but environmental considerations also must be addressed.
Material Finishes
Plug anchors and screws come in a variety of different materials, and are often coated with unique finishes to ensure durability and longevity. These finishes hold up against weather conditions and other types of wear and tear. The recommended type of material finish depends on your project and materials being used in the application.
The most common material finishes include:
Steel zinc
Steel zinc is a preferred choice for a material finish because of the exceptional corrosion resistance and durability benefits. The zinc coating acts as a protective layer, shielding the steel below from rust and damage. Additionally, it looks nice with a sleek, glossy appearance, making it a great solution for various industries, such as construction, automotive, and manufacturing.
Zinc alloy
Zinc alloy is often used as a material finish due to its versatility and aesthetic appeal. It is made with zinc mixed with other metals, to improve overall strength and durability. A variety of finishes are available (polished, brushed, or matte), and it is often used for furniture, hardware, and other applications.
Lead alloy
Lead alloy was popular in the past, but isn't used as often now due to its toxicity. If lead alloy is used, then additional materials finishes are likely recommended to minimize safety concerns.
Steel Zinc Polymer
Steel zinc polymer is a modern material finish that combines the strength and corrosion resistance of steel with a polymer coating for weather resistance and a sleek appearance. Steel zinc polymer holds up well against rust and wear, and is often used for outdoor furniture, automotive components, and architectural structures.
Galvanized Steel
Galvanized steel is a material finish that uses a layer of zinc over the top of regular steel. The silver-gray appearance is modern and stylish. The zinc is added to improve corrosion resistance, which is why galvanized steel is often used for outdoor applications, such as construction, automotive, and agricultural industries.
Stainless Steel
Stainless steel is versatile when used as material finish, and often preferred because it is strong, durable, and resistant to corrosion. It is often used in architecture, kitchenware, and medical equipment. In addition to the functional benefits, it offers a sleek and lustrous appearance while holding up well in even the harshest environments.
Conclusion
As you can see, there are many different types and styles of anchors to choose from. These products can be used in a variety of applications, helping to add the anchoring and strength you need to ensure durability.