A Guide to Wedge Anchors in Brick Applications
Securing anything to a brick wall used to require time-consuming drilling and masonry screws. But with wedge anchors, you can firmly fasten building materials, fixtures, equipment, and more to brick quickly and easily.
Keep reading to learn all about using wedge anchors in brick wall applications.
What Are Wedge Anchors and How Do They Work?
Wedge anchors, also called clip anchors or expansion anchors, are steel fasteners designed to provide solid holding power in concrete, brick, and other masonry materials.
They consist of two pieces - a threaded stud or bolt, and a separate expansion clip. The clip is forced outward by the tapered end of the bolt as it's driven into a pre-drilled hole. This creates tremendous gripping power and friction against the sides of the hole.
Types of Wedge Anchors
Wedge anchors come in a variety of sizes and materials:
- Zinc-plated carbon steel - for general indoor use
- Galvanized carbon steel - for outdoor applications
- Stainless steel (304 or 316 grade) - for highly corrosive environments like coastal areas
The type of steel used impacts an anchor's durability and corrosion resistance. For example, a hot-dipped galvanized carbon steel wedge anchor will stand up better to outdoor exposure than a standard zinc-plated anchor. Stainless steel offers maximum rust and oxidation resistance.
Advantages of Wedge Anchors
Compared to other concrete and masonry fasteners, wedge anchors offer several benefits:
- Can support both dynamic and static loads
- Resist tension, shear, and vibration forces
- Quick and easy installation without epoxy or grout
- Reusable by backing off nut to remove anchor
Wedge anchors can handle multi-directional and tension loads better than many alternatives. Their push-through installation is also faster than torque-controlled or epoxy anchors.
How Wedge Anchors Expand
The wedging action that creates holding power occurs in three stages as the anchor is tightened:
- The conical bolt end contacts the expansion clip legs, forcing them outward.
- The legs drag against the hole walls, creating friction.
- At full torque, the legs reach maximum outward expansion.
The pressure exerted by the tapered bolt end pushes the clip legs into the hole walls. As the legs try to expand, friction builds until the anchor wedges tight. Anchors should be designed and tested so that the base material fails before the anchor does in a pullout situation.
When To Use Wedge Anchors in Brick
While poured concrete is an ideal base material for wedge anchors, they can also provide plenty of gripping power in brick walls.
Hollow and Solid Brick
Wedge anchors are effective in both hollow and solid fired clay bricks. Just ensure bricks are hard-burnt and not underfired. Anchor capacity depends on brick compressive strength.
Hollow bricks provide less gripping surface than solid bricks, so a larger diameter anchor may be required to achieve the same load capacity. Always test a sample of the bricks being used to quantify strength.
Mortared Brick
Mortar helps disperse loads across full bricks. But mortar strength and thickness impact gripping capacity. Test torque required to turn anchored bolts before use.
The mortar should be fully cured to reach designed strength. Weak or brittle mortar can crack when anchors expand. Match mortar type to anchor material so corrosion does not undermine bond over time.
Brick Wall Applications
Common uses for wedge anchors in brick include:
- Securing railings, equipment, machinery
- Fastening concrete forms and masonry ties
- Hanging signs, gates, pipes, lights
- Anchoring window frames or door jambs
Wedge anchors are a versatile solution for these applications because they can handle tension loads imposed by equipment as well as the shear loads of wall-mounted objects. Always check manufacturer load ratings.
Installing Wedge Anchors in Brick
Follow these steps to properly install wedge anchors in brick walls:
Drilling Anchor Holes
- Use a hammer drill and carbide-tipped masonry bit per ANSI B212.15
- Hole diameter should match wedge anchor size
- Drill depth is 1/4" to 1/2" deeper than required embedment
- Don't drill into mortar joints - only set anchors in full bricks
The hole must be slightly deeper than the minimum embedment depth to allow space for any dust in the hole. Using an improperly sized bit or drilling too shallow reduces holding values.
Preparing the Hole
- Clean hole thoroughly using compressed air or a wire brush
- Remove all loose dust and debris
- Make sure hole depth meets requirements
Proper hole cleaning prevents reduced friction due to dust interference between the wedge and hole wall. A depth gauge ensures proper embedment will be achieved.
Placing the Anchor
- Slide washer over threaded stud
- Thread on nut with 3-4 turns
- Drive anchor into hole by hand initially
- Use wrench or socket wrench to fully set the anchor
The washer distributes load to help prevent stud pullout. Only partially threading the nut prevents binding before the anchor sets. Never bottom out the anchor when driving it in.
Setting Proper Torque
- Tighten nut with torque wrench to required torque value
- Do not over torque - this can cause anchor or brick failure
- Recommended torque range is typically 15-25 ft-lbs
Torque directly controls the wedge anchor's expansion pressure. Too little torque provides inadequate anchorage, while too much can damage the anchor or base material.
Once installed, test anchors by hand for proper set and load capacity before relying on them in service.
Choosing the Right Wedge Anchor Size
Wedge anchor size selection depends on several factors:
- Load - Dead, live, wind, seismic loads
- Safety factor - ASD typically uses safety factor of 4x
- Brick thickness and compressive strength
- Minimum embedment - Up to 10x anchor diameter
The required embedment depth accounts for potential cracking and spalling stresses in the brittle brick medium. Testing brick strength beforehand provides crucial data for proper sizing.
Use published load tables or consult an engineer for proper wedge anchor sizing. Rules of thumb:
- Minimum anchor diameter is 1/4"
- Maximum anchor diameter in brick is 3/8"
- Edge distance is 10x anchor diameter
Staying within these general guidelines ensures suitable anchor capacity relative to the brick's strength properties.
Alternatives to Wedge Anchors in Brick
While wedge anchors work well in most brick walls, here are two alternatives to consider: