Wall Ties and Anchors: What’s the Difference?

Words: Patrick Morrissey, Jeff Scarpelli, Michelle Nobel
Photos: ConSpec Associates, Inc., PROSOCO,

The terms wall tie, veneer tie, and anchor are often used interchangeably throughout the masonry industry, but each term has a distinct meaning. To help clarify the terminology, the latest edition of the TMS 402/602-22, Building Code Requirements and Specifications for Masonry Structures, updated the formal definitions for each of the various connectors.

Anchor: metal rod, wire, or strap that secures masonry to its structural support.
Wall Tie: Metal connector that connects wythes of masonry walls together.
Veneer Tie: Metal connector that attaches masonry veneer to backing.

While the differences are small, they are important when discussing masonry design and restoration.

An anchor is the broadest term and refers to any component that transfers loads between the masonry and the supporting structure.

Within a multi-wythe masonry wall, Wall ties specifically connect two wythes of masonry, providing lateral stability and, where designed, allowing the wythes to act together as a composite assembly. Before metal wall ties became common, multi-wythe walls were frequently tied together using header bricks, where the short end (header face) is laid exposed, extending lengthwise into the inner portion of the wall to physically bond the wythes together.

Figure 1 Example of a traditional header brick wall tie construction.

Veneer ties connect a non-structural masonry veneer to its structural backup, transferring wind and out-of-plane loads while permitting the differential movement that naturally occurs between dissimilar materials. For example, when a new brick veneer is built attached to a wood or metal stud backup wall. In a sense, veneer ties can be seen as a subcategory of anchors, since they are used to attach the veneer to the structural backup support. The difference is that veneer ties are specifically designed for masonry veneer systems, while masonry anchors may include a wider range of connections used for restoration, repair, and structural stabilization.

Figure 2 Example of an adjustable veneer tie cavity wall construction.

In new construction, veneer ties, wall ties, and embedded anchors are designed as part of the wall assembly from the start of the project. These connectors are installed as construction progresses, becoming embedded within fresh mortar, grout, or concrete, where they provide the lateral connection between the building materials and supporting structure.

In restoration, engineers, architects, building envelope consultants, and restoration contractors must work with existing structures where distress has occurred over time. This deterioration could have resulted from original design or construction deficiencies, corrosion of embedded steel or ties, material aging, moisture intrusion, increased loading requirements, or other environmental factors.

Unlike new construction, existing masonry presents unknown conditions that cannot be fully evaluated until an in-depth investigation process is performed. These conditions could present themselves during the distress investigation, or afterwards while the repair work is being performed. Hidden voids, deteriorated mortar, and varying substrate strength could affect the selection and performance of a repair system. These challenges have driven the development of a wide variety of retrofit anchoring technologies over the past several decades.

Retrofit anchors are designed to be installed through the existing masonry structure, as part of a repair, restoration, rehabilitation, or structural strengthening project. Their purpose may include reconnecting separated wythes, re-attaching masonry veneer to its backup, stabilizing cracked masonry, securing stone or terra cotta elements, or addressing other structural deficiencies within the existing wall systems.

Originally, restoration anchoring systems were primarily installed using fully grouted cementitious anchors. In the early 1970s, resin-based adhesive anchors gained popularity as manufacturers introduced cartridge-dispensing systems that simplified installation and improved jobsite efficiency. These systems were quickly adopted throughout the industry due to their ease of use and reduced handling requirements compared with traditional grouting methods.

However, the performance of resin-based adhesive anchors is highly dependent on proper installation procedures, particularly hole preparation. Resin adhesives rely on chemical adhesion and bond transfer between the cured resin and the masonry substrate. As a result, drilled holes must be thoroughly cleaned to remove dust and debris that could interfere with bond development. Many resin systems require specific cleaning procedures, including brushing and compressed air cleaning, to achieve published performance values.

Figure 3 View of an epoxy screen tube anchor.

Cement-based adhesive grouted anchors also require proper hole cleaning to achieve consistent performance; however, their load transfer mechanism differs from resin adhesives. Cementitious grouts rely primarily on mechanical interlock and a cementitious bond between the grout, anchor, and surrounding masonry. Because the grout fills irregularities and encapsulates the anchor, these systems are generally less sensitive to minor variations in hole cleanliness compared with resin-based adhesives.

Resin-based adhesives may also have more restrictive installation requirements related to temperature, moisture, and weather conditions, as curing and bond development can be affected by environmental conditions. Cementitious grouts typically provide greater tolerance to variable field conditions when installed in accordance with manufacturer requirements.

As restoration projects increasingly involve challenging existing conditions, including variable substrates, moisture exposure, and limited access for quality control, cement-based grouted anchoring systems have seen renewed interest due to their durability and installation tolerance.

Other common anchoring styles include:

Mechanical Expansion Anchors (friction-based restraint)
Mechanical expansion anchors rely on expansion mechanisms to develop a connection within the masonry substrate. These anchors are typically torque-controlled, where expansion components are activated within the drilled hole to engage the surrounding masonry.

Unlike concrete expansion anchors, which are often designed to develop capacity through expansion pressure and clamping forces within a single structural element, masonry restoration expansion anchors are commonly designed to create a tension-free connection between separate wythes or components. The veneer and backup fastening components expand independently, allowing the anchor to transfer lateral loads without relying on clamping action between the masonry layers.

Mechanical expansion anchors gained popularity in the 1970s and 1980s due to their ease of installation, requiring no adhesives, mixing, curing time, or extensive hole-cleaning procedures.

Figure 4 View of a brass expanding mechanical fastener engaging a brick veneer and CMU backup wall.

Stainless Steel Helical Anchors (keying-based restraint)
Stainless steel helical anchors were developed in Europe in the 1980’s, where they were introduced into the US market in the early 1990’s. These anchors consist of a stainless steel shaft with helical fins formed along their length. Installation is typically performed by driving the anchor through a small-diameter pilot hole using an SDS+ rotary hammer set to hammer-only mode.

During installation, the helical fins cut a path through the masonry substrate and engage the surrounding material through a combination of mechanical interlock, friction, and bearing resistance. Because the anchor can extend through multiple wythes or components, it provides a continuous connection across the wall assembly and can accommodate variable existing conditions commonly found in restoration projects.

Figure 5 View of helical anchors

Impediment (Pattress) Plates (bearing-based restraint)
Pattress plate systems rely on surface-mounted bearing components to restrain and redistribute loads across the face of the masonry wall. Typically, these are used in conjunction with threaded rods connected to the framing systems: pattress plates provide a visible anchorage point that transfers the out-of-plane loads from the masonry wall into the building’s structural system through bearing action.

Figure 6 View of star-shaped pattress plates.

Injection Grout Sock Anchors (hybrid bearing-based, friction-based, and adhesive-based restraint)
Injection grout sock anchors consist of a cementitious grout system surrounding stainless steel reinforcement and contained within a porous fabric sleeve or “sock.” During installation, the unfilled sock is positioned within a drilled cavity or existing void within the masonry assembly. Grout is then injected into the anchor assembly, filling the sleeve and conforming to irregularities within the surrounding masonry.

As the sock is filled, a small amount of grout may migrate through the porous sleeve, creating a limited adhesive bond with the surrounding masonry. However, the primary load transfer mechanisms are developed through mechanical interlock with the irregularities of the surrounding substrate, bearing resistance of the cured grout, and friction developed along the length of the anchor assembly.

These systems are particularly useful in restoration applications where the existing masonry contains large voids, is rubble fill, or has deteriorated internal conditions that make traditional drilled and bonded anchors less predictable. The injection sock anchors are typically used in cases where supplemental shear or flexural strengthening of the masonry is required.

Figure 7 View of a sock anchor expanding within the voids of a mass masonry wall.

Figure 8 View of an expanded sock anchor within a hollow cavity.

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