Masonry & Concrete Anchors

Unlike wood and drywall, stone, brick and concrete surfaces are a little less likely to give way with ease when you try to drive in a fastener. Fortunately, there is a whole range of anchors specially made for working with these surfaces, and the good news is that with the help of a few basic tools, they' re pretty easy to work with. Choosing the appropriate anchor from a wide variety of available options, including sleeve anchors, toggle bolts, concrete screws and more, can be overwhelming. With a little bit of knowledge, however, you'll be sure to find what you need. Consider the following questions as you try to find the right type of anchor for your next project:

• What types of masonry and concrete anchors are available?
• What applications can they be used for?
• How do you insert different types of anchors?
• What tools will you need for the job?
• How obtrusive can the anchors be?

Applications, Usage, Types and Insertion

Whether you're securing a set of shelves to a basement wall, installing a new light fixture in the brick façade on the front of your house or hanging tool storage in your garage, masonry and concrete anchors will come in handy. Understanding the different types of loads they are able to bear and what kind of loads different objects create is key to choosing the best type of anchor to use. Once you've selected the right anchor for the job, you'll need to make sure you have the necessary tools on hand for installation. In some cases, a hammer drill may provide more utility than a standard cordless drill.

Applications and Loads: Anchors are used in situations where it's either impossible or impractical to insert a screw directly into a wall, such as when working with concrete or drywall. Once the anchor has been secured, a screw is inserted to hang a variety of different objects ranging from shelves and cabinets to paintings and mirrors. Anchors are subject to pull in two different directions. The shear load describes the amount of downward force gravity and the weight an object exerts on an anchor. Tensile load refers to the amount of force required to pull the anchor straight out of the hole. Both of these loads must be taken into consideration when installing an anchor. In order to make sure your anchors can safely hold the weight of the object you're attaching, a good rule of thumb is to assume that they can hold 1/4 of their stated load. For example, if an anchor is rated to hold 100 lbs., assume it can safely handle 25 lbs. Then, simply use a number of anchors whose total load when added up and divided by four is equal to or greater than the weight of the object being hung.

• Anchors can only hold as much weight as the wall they're attached to can bear
• Other types of loads anchors may bear are static, dynamic and impact
• Static loads are created by objects that never move and constantly exert the same force
• Dynamic loads are created by objects that move or vibrate, such as machines
• Impact loads are created when weight is increased suddenly, such as when a heavy book is placed on a shelf

Types: Masonry and concrete anchors are available in many different varieties. Generally, anchors function either by expanding once they're in place to provide a strong hold or by friction. The chart below lists some of the more commonly used types, the applications they're best suited for and a few points of consideration.

Anchor Type	Applications	Points to Consider
Concrete Screws	Used for various applications in concrete, brick or block, such as attaching furring strips, doors and electrical boxes.	Feature alternating high and low threads with diamond-cut notches that provide extra holding power May be sealed to provide protection against corrosion May be packaged with appropriately sized drill bits Can be removed with a screwdriver
Hammer-In Anchors	Various applications in concrete, concrete block, mortar and brick, such as hanging furring strips and metal brackets.	Easy to install Must be hammered into place Avoid using in crumbly surfaces Don’t require a separate screw
Lag Shields	Longer shields are best for use in hard masonry while shorter shields are better for softer materials.	Used in conjunction with lag bolts Short shields work well on shallow surfaces Long shields provide greater strength Drill the hole size specified by the embossing on the anchor
Lead Screw Anchors	Securing light to medium loads in brick, concrete block and masonry.	Require a pilot hole Expand once inserted to prevent turning and pullout
Plastic Wall Plug	Light-duty applications in masonry, such as towel bars, tool brackets and shower doors.	Tapered ribs prevent twisting
Sleeve Anchors	Medium-duty applications in concrete block, such as anchoring handrails, decks, machinery and shelves.	Length is measured from the washer to the end of the anchor Sleeves pinch the side of the pilot hole and get tighter as the screw is driven into place
Toggle Bolts	Light to medium loads in hollow block.	Feature a set of wings that spring open once bolt has been placed in hole and screw has been tightened Wings provide a brace against the backside of the wall for a secure hold
Wedge Anchors	Heavy-duty load applications in concrete blocks and thin-wall or solid concrete, such as anchoring machinery and attaching framing members.	Length is measured from end to end Stainless-steel expansion clip offers resistance to corrosion Extremely strong Once they have been inserted, they are nearly impossible to remove

Insertion Tips and Tools: Regardless of which type of anchor you select, you're going to need to drill a pilot hole. Masonry and concrete are tough surfaces to drill through, so make sure you have plenty of extra bits on hand. Some anchors will require spotting prior to insertion. Spotting involves positioning the fixture to ensure the fasteners will be secured in the correct spot prior to drilling a pilot hole. Others, referred to as one-step anchors, do not need to be spotted. Once you've drilled your pilot hole, use a can of compressed air or a blower to clean out the hole. Excess debris can prevent the anchor from being properly secured. Avoid placing anchors too close to each other or the edge of the surface you're working with, as the stress may cause it to fracture.

• Drills, hammer drills, screwdrivers and hammers may be needed for insertion
• Masonry drill bits are specially designed for cutting through stone and include self-cleaning spiral flutes that lift cuttings out of the hole as it's drilled
• Some anchors come with drill bits specially sized for the pilot holes they require
• Always wear safety goggles and a dust mask when drilling

Features

Chemical and Powder-Actuated Anchors: All of the anchors discussed above are mechanical anchors. If you're working with an extremely heavy object that requires an industrial-strength hold, you may want to consider using a chemical or powder-actuated anchor. These anchors use chemicals such as epoxy to strengthen the bond. They are not required for most household applications, however, and you'll need special training and possibly a license before being able to use them.

Antirotation Fins: This feature prevents anchors from spinning while they are being inserted, which strengthens their hold once inside the wall.

Hammer Drill: Regular drills work well for installing anchors in wood and drywall. Stone, concrete and brick, however, can prove to be tough customers. Hammer drills combine the driving force of a drill with the pounding action of a hammer, making it easier to bore into hard surfaces. If you don't plan to undertake a lot of projects involving masonry and concrete, consider renting a hammer drill from The Home Depot.