Hidden from View: Investigating Masonry Veneer Anchorage

Hidden from View: Investigating Masonry Veneer Anchorage


Read this: https://www.seattle.gov/dpd/codes/dr/DR%206%202023.pdf

Stewart M. Verhulst, M.S., P.E., RRC, M. ASCE

V.P. and Executive Technical Director, Nelson Forensics, 9701 Brodie Lane, Suite 201, Austin, Texas 78748; email: sverhulst@nelsonforensics.com; phone: 877-850-8765

J. Daniel Bosley, M.S., P.E., M. ASCE

Regional Manager, Nelson Forensics, 9701 Brodie Lane, Suite 201, Austin, Texas 78748; email: dbosley@nelsonforensics.com; phone: 877-850-8765

Alan Pettingale, Restoration Consultant

President, Specialized Masonry Restoration, 3318 County Road 275, Melissa, Texas 75454, website: www.alanpettingale.com; phone: 469-766-1167


Deficiencies in masonry veneer attachment can result in sudden or premature failures. Such failures can result in safety hazards due to falling veneer, especially in areas where the veneer is overhead adjacent to common walkways or locations of ingress/egress. However, the veneer attachment is not typically visible and; therefore, attachment issues, whether they are from defects in the original veneer installation or related to deterioration over time, may not be readily apparent until a failure has occurred. This paper addresses anchored masonry veneers, such as brick and natural stone, and discusses investigation methods varying from non-destructive evaluation, to minimally-destructive observation, to localized veneer removal. Non-destructive determination of anchorage locations can be used to identify as-built deficiencies and to highlight areas for further (destructive) testing and detailed observation. Examples of such non-destructive wall tie location surveys are presented, and the evaluation of deteriorated anchorages (i.e., wall tie corrosion) is also discussed.


Masonry veneer systems typically consist of a single layer of brick, concrete, artificial stone, or natural stone units attached to the walls and other elements of a structure. Modern masonry veneer systems are most commonly attached with metal veneer anchors (wall ties) or adhered with mortar to the underlying structure.

The discussion presented herein focuses on the attachment of anchored masonry veneer systems used in modern cavity wall construction. The typical components of a cavity wall are shown in Figure 1, and consist of: cladding (e.g., masonry veneer), air space (drainage cavity), air and moisture barrier (drainage plane), exterior sheathing, framing and insulation, and interior wall finishes.

Figure 1: Typical Cavity Wall Components

Masonry veneers utilized in cavity wall construction must be supported by, and mechanically attached to, the building structural elements in order to transmit vertical loads from the weight of the veneer and lateral loads from forces applied to the veneer (e.g., wind and seismic loads) to the underlying structure.

Lateral loads on masonry veneer systems utilized in cavity wall construction are transmitted to the underlying structure primarily through the masonry veneer anchors. These anchors may consist of a single element (i.e., “box” ties, “Z” ties, and corrugated ties) commonly referred to as “unit ties”, continuous horizontal joint reinforcement, and adjustable ties with multiple components. There are a multitude of veneer anchor types for various applications. Common examples of veneer anchors are shown in Figure 2 for illustrative purposes.

Figure 2: Common Masonry Veneer Anchors.

For a veneer anchor system to properly serve its intended function, the anchors must be appropriate for the particular application, properly distributed within the veneer system, correctly attached to the veneer and the underlying supporting structural system, and in sound condition. The veneer anchor system must also have sufficient stiffness to transfer lateral loads with minimal deformations, to limit deflection and associated damage to the veneer.

A detailed discussion of building code requirements for masonry veneer installation is beyond the scope of this document; however, such requirements can be found in contemporary building codes, such as the International Building Code (ICC 2017) and The Masonry Society publication Building Code Requirements and Specifications for Masonry Structures (TMS 402/602-16) (TMS 2016). Any veneer system evaluation should consider the relevant portions of these documents.


Background. Non-destructive surveys can be used to determine the locations of veneer anchors within a masonry veneer system with a high degree of accuracy. The data obtained in the non- destructive surveys provides information regarding the locations of individual veneer anchors, which can then be used to assess the distribution/spacing of the anchors. This survey data can be compared to project and building code requirements to assess the adequacy of the anchor distribution, and can facilitate the identification of potential safety issues due to a lack of proper veneer anchorage. Such surveys can also be used to identify locations where destructive testing can be performed to gather additional or more specific information regarding the anchor installation or the condition of the anchorages.

Survey Methodology. The non-destructive veneer anchor survey process is similar to methodologies utilized to determine the locations of reinforcing bars in concrete. The surveys discussed herein were performed using an Imp Wall-Tie Locator, manufactured by Protovale®; however, various similar devices are available. The Imp Wall-Tie Locator uses magnetic pulse induction from a wire coil to detect metal veneer anchors embedded in the mortar beds of the veneer. The device includes a hand-held search coil that attaches to a control unit carried by the operator (Figure 3). The sensitivity of the device can be adjusted on the control unit to detect anchors at a range of depths. The operator receives an auditory alert when the presence of a veneer anchor (or other metallic object) is detected.

The survey methodology consists of selecting survey areas at accessible portions of the veneer, determining the veneer anchor locations by traversing all mortar joints within the survey area with the search coil, and marking the locations of detected anchors with tape, chalk, or other means (Figure 4 and Figure 5). The size of each survey area, the number of veneer anchors detected, and the locations of the detected veneer anchors is then documented.

Figure 3: Overview of the Imp Wall-Tie Locator.

Figure 4: Overview of non-destructive survey in progress.

Figure 5: Wall tie locations marked within survey area.

In the authors’ experience, traversing the mortar joints with the Wall-Tie Locator set to a higher sensitivity provides a good initial indication of the general location of the veneer anchors; more precise locations for the anchors can then be determined by reducing the sensitivity of the instrument. The authors find that heavy-duty tape (duct tape, or similar) applied to the veneer is an effective method for recording the locations of the detected veneer anchors, because the tape does not mar or stain the veneer surface and the tape locations can be moved to accommodate the increased precision of anchor locations during the survey. Additionally, various colors of tape are available to allow for good contrast/visibility in photographic documentation, and removal of the tape without causing residual surface damage is easily accomplished after completion of the survey.

Wall Tie Locations Identified

Once a survey has been performed, the anchor distribution can be analyzed considering the overall density of anchors (i.e., wall area per anchor) and the distribution/spacing of the anchors within the surveyed areas. Some areas of a veneer system may exhibit significantly higher or lower anchor densities. For example, the authors have found that anchor density is commonly higher directly above steel lintels spanning doors and windows, while adjacent areas in the field of the wall will commonly have lower anchorage density, and some areas may have little to no veneer anchorage (Figures 6 and 7). In such cases, analysis of the veneer anchorage may be best performed by considering the density of anchorage directly above the openings separately from the anchorage at the remainder (field) of the wall area.

Figure 6: Overview of typical survey area at stone masonry veneer.

Figure 7: Overview of typical survey area at stone masonry veneer.

The authors have achieved a high degree of accuracy in determining the locations of veneer anchors via non-destructive surveys for cavity wall systems anchored to wood framing, steel framing, and concrete masonry superstructures. Accuracy of the survey method was verified by performing non-destructive veneer anchor surveys at areas where some destructive testing was scheduled to take place. Therefore, the locations of detected anchors could be compared with conditions actually observed within the wall cavity.

In one such example of survey verification, the authors detected 413 suspected anchors. Seven (1.7%) of the suspected anchors were metallic debris (such as soda cans) behind the stone veneer, five (1.2%) were anchors that were not fully engaged with the veneer, and three (0.7%) were false positives where no anchor was present at the suspected location. Therefore, approximately 96.4% of the suspected locations of fully engaged veneer anchors were confirmed by destructive testing. However, the authors observed twelve fully engaged anchors at areas of stone veneer removal that were not individually located by the veneer anchor surveys. Of these anchors that were not detected, four were located in close proximity to other anchors or metal objects, and therefore were not individually detected. Therefore, 398 of the 410 (97.1%) fully engaged anchors that existed within the areas evaluated were detected in the surveys.

At another property, veneer anchor surveys were performed at multiple buildings, including areas with both stone veneer and brick veneer, and the findings were verified with follow-up destructive testing. For these surveys, the authors achieved an accuracy of approximately 95.7% (i.e., approximately 95.7% of the veneer anchors observed during destructive testing were identified by non-destructive surveys prior to veneer removal).

The surveys at this property also indicated a distinct difference in the anchor densities based on veneer type: less than 60% of the required anchors were installed at the surveyed stone veneer, while approximately 94% of the required anchors were installed at the surveyed brick veneer. The anchors for the brick veneer were also more evenly distributed, and more closely complied with code-prescribed spacing requirements (Figures 8 and 9).

Figure 8: Overview of typical survey area at brick masonry veneer (anchors chalk “x” markings).

Figure 9: Overview of typical survey area at stone masonry veneer.

The coursing of stone veneer is somewhat irregular when compared to the consistent coursing typical of brick veneer. This is particularly true when considering stone veneer with a rubble masonry configuration. Irregular coursing makes it inherently more difficult to install veneer anchors at regular intervals, and this may affect the density of the installed anchors. This is an example of an issue that, while not visibly apparent at the face of a veneer wall, can be studied using non-destructive veneer anchor surveys.

In some cases, veneer anchors that are not properly embedded within the veneer (Figure 10) can be identified based on the difference in auditory feedback on different sensitivity settings.

Alan Pettingale

Figure 10: Veneer anchor that was detected during a survey but not anchored into the veneer.

Because the Wall-Tie Locator detects the presence of metal within the wall/veneer system, care must be taken in adjusting the sensitivity of the Wall-Tie Locator when performing surveys over steel framing, due to the potential for interference caused by the framing system. Other factors that the authors have found to contribute to interference during the veneer anchor surveys include metallic appurtenances (such as gutter downspouts, metallic lights, metal fences, metal flashings/accessories, and utility penetrations), metal lath lapped behind the veneer (such as from an adjacent stucco or adhered veneer system), foil-faced sheathing, and metallic debris within the wall cavity. Care should be taken to avoid potential sources of interference and to eliminate or significantly mitigate the effect of such interference on the results of the survey. If erratic soundings by the Wall-Tie Locator are prevalent, destructive testing may be prudent to determine the cause of the interference and to develop strategies to minimize its effect on the accuracy of the veneer anchor surveys.


Determining veneer anchor locations non-destructively provides valuable information regarding the location of the veneer anchors, but does not establish the condition of the veneer anchor (e.g. if it is corroded/deteriorated) or the adequacy of the veneer anchor attachment to the structure or veneer. However, the ability to accurately determine the locations of the veneer anchors in a non-destructive manner can facilitate a focused approach to destructive testing, thereby limiting the invasiveness of the veneer evaluation.

The distribution of veneer anchors detected by non-destructive surveys can be used to identify irregular patterns of anchor installation and anchors that are likely not properly attached to the underlying framing members. Detection of veneer anchors that are randomly placed and not aligned vertically at regular intervals, provides an indication that a portion of the veneer anchors are not installed into framing members and are instead connected only to the sheathing. Placement of veneer anchors into sheathing (rather than framing) reduces the withdrawal resistance of the veneer anchor. Therefore, although the veneer anchor surveys verify the existence of these anchors and the anchors are engaged with the veneer, the anchors may be providing insufficient lateral support for the veneer.

Minimally-Invasive Destructive Testing. Minimally-invasive testing to visually assess veneer anchor conditions can be performed with a borescope or by removing individual masonry units. Non-destructive surveys (such as those discussed in the preceding section) can help to determine the locations for minimally-invasive testing, in conjunction with the specific requirements of the project. In some cases, locations targeted for destructive testing may be informed by the pattern/distribution of the veneer anchors detected in the survey and/or by conditions on the surface of the veneer (such as cracking, spalling, or discoloration) that indicate the potential for an underlying issue. Destructive testing locations may also be based on a random sampling chosen to assess the general condition of the veneer attachment. The specific testing protocol utilized should be determined based on the unique characteristics of a given project.

The borescope destructive testing method involves drilling a hole into the mortar joint or masonry unit at the area(s) to be evaluated and inserting a scope into the drilled hole in order to observe the conditions within the veneer cavity. Evaluations with a borescope are generally limited to a visual assessment. A camera attachment can be used on the scope to document the conditions observed (Figure 11).

Figure 11: Evaluation of veneer anchor with borescope.

Removal of individual masonry units involves saw-cutting or chipping away the mortar around the perimeter of the masonry unit (or units) to facilitate removal. Removal of individual masonry units may provide better visibility of the veneer anchorage conditions, when compared to the borescope method. Additionally, removal of individual masonry units may facilitate the evaluation of the veneer anchor attachment to the structure and veneer, such as by measuring the depth of anchor embedment into the veneer mortar joints, determining the location of attachment of the veneer anchor fastener to the structure (i.e., determining if the anchor is correctly attached to the structural framing), and/or determining the strength of the veneer anchor attachment to the structure such as by pull testing.

Figure 12 shows an example of an anchor exposed with limited veneer removal. This revealed that the stainless steel anchor had been installed with a mild steel fastener (which had started to corrode) and that the installation was such that the anchor was restraining further vertical movement of the veneer.

Figure 12. Tie installed such that it restrains vertical movement of the veneer.

Large-Scale Veneer Removal. Larger-scale removal of a veneer system may be warranted depending on the specific parameters of a given veneer system evaluation. Non-destructive veneer anchor surveys may provide minimal additional information in the case of larger-scale veneer removal; however, these surveys may assist in determining the locations where larger-scale removal would be most informative. Additionally, by performing a non-destructive survey prior to the veneer removal, the accuracy of the non-destructive method can be assessed, which may be beneficial to other aspects of a given project.


The corrosion deterioration of veneer anchors, or of the framing supporting the veneer (such as steel stud framing), is a topic worthy of extensive and detailed discussion beyond the scope of this document. However, a brief discussion is warranted herein due to the severity of the problems that can result from veneer anchor corrosion. The corrosion deterioration of veneer anchors within a cavity wall is typically not visible and often goes unrecognized until a failure occurs. Figures 13 and 14 depict conditions observed after a portion of a veneer wall collapsed at a school campus building. Veneer anchors had corroded through their cross section within the wall cavity. However, the deteriorated condition of the anchors was not known prior to the collapse, which occurred suddenly. It should be noted that this structure was not located in a coastal area.

Figure 13. Corroded and failed veneer anchors at a collapsed veneer wall.

Figure 14. Corroded and failed veneer anchor at a portion of the wall that had not yet collapsed.

Awareness of the potential for veneer anchor corrosion has increased over time and with changing construction methods related to veneer walls (BIA 2003). The authors have observed veneer anchor corrosion to varying degrees and have observed the beginning stages of base steel corrosion in veneer anchors very early in their service lives, even in non-coastal locations. The authors have also observed base steel corrosion at galvanized veneer anchors in buildings one-year of age and less (Figure 15).

Prolonged or severe exposure to moisture or other deleterious elements (such as chlorides or acids) may compromise the veneer attachment over time due to deterioration of the veneer anchors or structural system to which the anchors are attached. The potential for corrosion of veneer anchorage is a function of exposure conditions for a given building (dependent on geographic location); construction material selection and compatibility; and detailing, workmanship, and maintenance.

Alan Pettingale

Figure 15. Veneer anchor corrosion at a structure less than one-year of age.

Deficiencies in the veneer anchors themselves can also affect the integrity of an anchored veneer. Some common deficiencies include the use of the wrong anchor type or material (such as galvanized instead of stainless steel), improper installation of the anchor, and improper anchor placement.

Deficient or deteriorated masonry veneer attachments have the potential to result in sudden or premature veneer failures, and associated safety hazards and damage to property. Due to the concealed nature of the veneer anchorage, non-destructive and destructive methodologies may be required to evaluate a masonry veneer system. Over the course of multiple evaluations of masonry veneer systems, the authors have determined that a combination of the evaluation methodologies described above can be reliably used to determine the characteristics, distribution, and condition of masonry veneer anchors.


While masonry veneer anchors are hidden, non-destructive testing can be used to accurately determine the anchor locations. Data from non-destructive surveys of masonry veneers can be used to evaluate the distribution of the veneer anchors and to identify locations for further testing and detailed observation.

Non-destructive surveys to determine veneer anchor locations, followed by minimally-invasive destructive evaluation of the cavity or localized veneer removal, is an effective method to evaluate the condition of veneer anchors within cavity wall systems, including the identification of veneer anchor deficiencies or deterioration.

While this paper is presented to a primarily American audience, the authors would like to highlight some resources from outside the United States that may be useful to the reader. The Building Research Establishment (BRE) in the United Kingdom has published multiple documents related to the assessment of masonry veneer anchors, the corrosion of anchors (wall ties), and the repair of anchored veneer. These documents include BRE Digest 329 (Installing wall ties in existing construction), BRE Digest 401 (Replacing wall ties), and BRE Information Paper 13/90 (Corrosion of steel wall ties: recognition and inspection).


International Code Council, Inc. (ICC). 2017. 2018 International Building Code, ICC: Country Club Hills, IL.

The Brick Industry Association (BIA). 2003. “Technical Notes 44B – Wall Ties for Brick Masonry,” Technical Notes of Brick Construction. BIA: Reston, VA.

The Masonry Society (TMS). 2016. TMS 402/602-16 Building Code Requirements and Specifications for Masonry Structures. TMS: Longmont, Co.

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Alan Pettingale

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I help Engineers, Architects, and Contractors to fix, to educate and remediate with masonry restoration techniques using both historic and cutting edge technology, including drones for observation.

I help Engineers, Architects, and Contractors to fix, to educate and remediate with masonry restoration techniques using both historic and cutting edge technology, including drones for observation.





Anchor systems in masonry walls have been used for centuries, with the earliest dating back to the Romans and Greeks who used wrought iron to supplement conventional masonry. Other cultures and countries have used variations of metal anchors and straps in the construction of masonry, as well as for retrofit or repair applications to supplement and strengthen masonry systems after natural disasters such as earthquakes. There are numerous modern applications where lateral restraint anchors can be utilized to remediate masonry walls that are in service to accommodate additional applied forces or to strengthen masonry weakened by deterioration or excessive load. Often, lateral restraint anchors can utilize the existing interior framing of a building to re-establish a point of support at an intermediate height of the wall. This is accomplished through a combination of fasteners or anchors that secure straps, rods, or other tension elements to the masonry wall to resist lateral displacement. Many of these applications merge the basic premises of historic methods with techniques and modern materials of the twentieth century to provide a cost effective, aesthetically appealing, and preservation oriented method for remediating masonry. This merger of old and new techniques allows us to stabilize historic walls for modern service conditions allowing them to continue serving their intended function.

Keywords: Masonry, Repair, Restoration, Anchor, Lateral Restraint

1 Owner, Specialized Masonry Restoration, 3318 County Road, Melissa, TX 75454, USA alan@specializedmasonryrestoration.com

2 Senior Associate, Whitlock Dalrymple Poston & Associates, P.C., 10621 Gateway Boulevard Suite 200, Manassas, VA 20110, USA, epeterson@wdpa.com


Many multiwythe masonry walls never have an opportunity to attain historic status. They are subjected to the elements as they carry the loads intended by their designers and constructors, and slowly, they weather and degrade. For the exterior walls of these buildings, often maintenance is forgone, and the damage sustained to the exterior surfaces over time, coupled with eccentric gravity loads from floor and roof systems of the building, will result in lateral displacement of the walls. As the movement progresses, it eventually reaches a point where it compromises the integrity of the structure. Other times, lateral loads from earthquakes, soil pressure, or other imposed loads can result in damage to a wall system that can equally compromise the structure. The typical repair options for multiwythe walls with significant damage or displacement entail partial reconstruction or other prohibitively expensive programs. Without more cost effective alternatives, many of these buildings remain unrepaired and continue to degrade until they become unstable or derelict, running a rapid path to demolition.

If these wall systems can be stabilized at intermediate points of support prior to becoming unstable, the rate of decay can be considerably reduced and the lifespan of many of these buildings can be extended. Over the years, the most effective method of providing lateral stability has been the installation of lateral restraint anchors. A lateral restraint anchor is a combination of anchors, bars, ties, cementations, grouts, and resins used to remediate and stabilize masonry or stone walls against lateral movement. These elements can arrest the natural tendency of exterior walls to bulge at floor lines, and when installed in conjunction with an aggressive tuck pointing program to reduce the natural weathering of the masonry, can prolong the service life of the building.

Historic Perspective

Stone and masonry anchors have been noted in history as far back as the Romans and Greeks for masonry repair. The anchors of ancient times were plain bars made of wrought iron, using metal straps to anchor buildings and ensure their stability. But it was the Dutch, as early as the 1550s, who used them the most. These Dutch iron anchors originated in the lowlands, on barns, houses, and mercantile buildings and were called Muurankers.

Muurankers were inserted during construction and were not intended for remediation. They served as part of the building’s primary frame to associate each transverse beam with the wall to resist lateral loads. As time went on, they became architectural features on the buildings, taking the form of the initials of the builder, the owner, or the marks of merchants to advertise their work. In the 1800s, Dutch foundries began making shorter anchors out of cast iron to create decorative symbols like rosettes and Fleur-de-lis to improve the aesthetic of the anchor. This system of anchoring exterior walls to the frame spread over Europe.

Patress plates and bars (patress derived from the Latin ‘pateras’, meaning a shallow bowl or plate) were anchors used extensively in Great Britain to provide lateral support to masonry walls. The iron patress bar was inserted through an exterior wall on one side of the building and threaded through the joists and framing and then returned through the opposite wall where plates were attached to the ends of the bars by a bolt. A turnbuckle attachment on the interior was used to apply tension to the bar in order to stabilize the building (Figure 1). These elements fell out of favor over time because the plates on the outside of the buildings corroded, leaving stains on the stone and brick masonry, detracting from the buildings’ aesthetic appeal.

Figure 1. Patress plates on a façade parapet

In North America, settlers utilized permutations of several building techniques in the construction of their houses and mercantile structures, but were influenced primarily by the European building techniques. Plates and anchor rods were used primarily for remediation of masonry failures and damage during storms or earthquakes. The star anchor was favored in eighteenth and nineteenth century brick construction and can still be seen throughout the southeast, particularly in areas like Charleston, South Carolina, where seismic activity is most prevalent. These anchors were commonly called earthquake washers and were used to stabilize structures weakened over time due to shifting soil conditions or earth movements.

Modern Applications

There are many modern applications where lateral restraint anchors can be utilized to remediate masonry walls in service in order to accommodate applied loads or to strengthen masonry walls weakened by deterioration or excessive load (such as an earthquake). Many of these applications merge the basic premises of the above mentioned historic methods with techniques and modern materials of the twentieth century to provide a cost effective, aesthetically appealing, and preservation oriented method for remediating masonry.

The most common structures that may benefit from these techniques are nineteenth century two and three story mercantile structures commonly found in the small town centers of the United States. Many of these structures share common walls between buildings with variable roof heights and eccentric loads on each side of the wall (Figure 2).

Figure 2. Separation and displacement of common wall.

Uneven weathering and the lateral thrust of roof and floor systems can result in lateral displacements and distress at building perimeters. This lateral movement can become visible at interior walls where plaster and molding begin separating at ceilings (Figure 3). Many of these buildings utilize large rough hewn non-dimensional timbers set in fire cut sockets of the masonry or on timber framing elements with mortise and tennon joinery. This type of horizontal framing can provide a robust diaphragm when the framing elements are tied together and confined or restrained laterally. For these applications, lateral restraint anchors can be installed to utilize the existing interior framing system as a point of support at an intermediate height of the wall. The reduction in unbraced length serves to re-establish the stability of the wall and resist further displacement.

Figure 3. Separation of common wall floor system on interior of building. Repair Strategies

The selection of the proper lateral restraint system depends on several factors, including the existing construction of the floor and wall systems, the condition of the masonry and timber, the access to the interior and exterior sides of the wall, and the extent or severity of the existing displacement. While there are a number of different lateral restraint anchor configurations that may be employed, this paper focuses on the overriding principals of the repair strategies.

As with any retrofit lateral restraint system, the first step in the repair design is the development of the design loads. Lateral loads from seismic and wind forces can be developed directly from the applicable local code provisions. Additionally, the gravity loads resisted by the wall system including dead, live and snow loads must be generated, combined appropriately with other loads, and applied taking into account the appropriate eccentricities that generate internal moments and shears in the masonry. The joist seat details must be evaluated to determine distance from the centroid of the wall system to the line of action from the bearing seat. It is also important to incorporate any observed out of plane displacement in the wall, which will often times increase the thrust at the lateral restraint anchor due to the increase in the internal moment in the wall.

After the static forces in the wall are resolved, the lateral restraint is modeled as a new support element at an intermediate point in the wall. The type of lateral restraint system used is often based on the magnitude of the lateral thrust to be resolved and the construction or configuration of intermediate floor and roof systems. If the lateral restraining force to be resolved by the anchor system is relatively low, (on the order of 200-250 lbs per foot) it is often suitable to utilize the existing interior framing system to provide the necessary restraint. However, depending on the construction of the floor system, more flexible framing configurations may require more complex computations by modeling the support as a lateral spring versus a point of fixity in order to accurately resolve the resisting force generated.

As the lateral restraining force increases, it becomes more difficult to resolve the stresses generated by adhesive or expansion anchors in the existing brick masonry and shear fasteners in members of the framing system. Depending on the configuration of the building, higher loads may require the resolution of the forces by anchoring to opposite or interior walls independent of the floor system and the use of patress plate type elements to distribute anchor forces in the existing masonry walls.

Generally, it is advantageous to configure lateral restraint anchors to resist both tension and compression. A reversal of displacement is possible after repairs are performed. Also, the installation of noggings or blocking between framing elements and shims or wedges between the flooring and wall system allows an even transfer of forces into the framing.

For walls running perpendicular to the primary framing joists, the joists can be utilized in direct tension as a strut between opposite walls. Joists must be continuous to employ this strategy. Otherwise, modification of splices and joints must be performed to transfer load across the joists. In one configuration, an anchor plate or angle is affixed to the masonry wall, using either anchors fixed in an epoxy resin or a mechanical anchor, midway between each of the joists. If the floor system is accessible from the underside, a stainless or galvanized tension strap can be affixed to each side of the joists with a series of shear fasteners to transfer the load from the wall into the joists (Figure 4). Spaces between joists and walls can be filled with mortar or resin to engage the joists in compression. Fastener spacing, stagger and interaction with plates on opposite sides of the joist must be taken into account to insure the maximum tensile force can be obtained in the tension straps.

Figure 4. Retrofitting of masonry walls using straps and anchors (Top – utilizing straps between joists, Bottom – straps secured to top of joist under flooring)

Conversely, if access to the sides of the joists is limited, more substantial strapping plates, similar to earlier muuranker style connections, can be affixed to an angle on the top side of the joist and then fastened to the masonry wall using a similar masonry anchor. The area of the upturned strap leg should be sized to serve as a bearing surface against the masonry (Figure 5).

Figure 5. Muuranker style of retrofit wall repair utilizing straps along the top of the joist

When the primary framing joists are running parallel to the wall, it is more difficult to develop a reliable tensile force to resist the tendency for outward displacement of the masonry. Much like with the patress plates and earthquake washers of earlier years, if access can be obtained to opposite walls of a building, a threaded rod can be fed through the wall and into the floor framing to secure opposite walls to one another. Either decorative, non-corrosive patress plates can be installed on the exterior, or to minimize the impact to the appearance of the building, the threaded rod can be affixed with an epoxy resin within the masonry walls. The hole in the masonry is then filled with a tinted mortar or resin plug to match the exterior. This repair approach is particularly useful in the event the rigidity of the floor system is inadequate in tension to utilize as bracing, but can be supplemented with blocking and wedges to provide compressive restraint (Figure 6).

Often with older buildings, the floor system will have rough hewn timbers possessing sufficient lateral bending strength to provide resistance to the outward thrust. If so, discrete threaded anchors can be installed passing through multiple joists and affixed to the timbers with washers and nuts to secure the rod in place. The rod is then affixed in the masonry with epoxy and wedges or noggings installed between the joists to distribute the loads into the flooring system. Alternatively, a strapping system with associated blocking can be secured above or below the joists with shear screws to develop the lateral resistance (Figure 7). Of critical importance with this design is establishing a load/deflection relationship between the flooring system and the wall to determine how much lateral support can be derived from the flooring. Also, connections in the wood framing must be analyzed to ensure that the load transfer from the anchors into the framing does not exceed dowel or tendon capacities. Figures 6 and 7 depict the design and construction of such a strengthening technique.

Figure 6. Alternatives for lateral wall ties utilizing existing transverse floor elements.

Bryan Hindle (Brick-Tie)U.K.

Figure 7. Installation of tension straps in joists parallel to wall.

Material selection of the elements utilized for the masonry anchors is of critical importance with regard to exterior wall systems. Most multiwythe masonry walls are constructed as mass walls that do not manage water through the use of water resistive barriers and flashings, and as such, when exposed to the environment would be expected to take on significant volumes of water within the section of the wall. Therefore lateral restraint systems utilized in exterior walls must have some method of corrosion protection to provide a durable and lasting repair. Normally, steel components embedded in either epoxy resin or cementitious grout would be adequately protected from corrosion. However, it is often very difficult to ensure complete encasement of the embedded wall elements because they are installed either “blind” or with single sided access. Inadequate coverage and localized exposure of these elements to moisture can then result in corrosion and the expansion of the iron oxides can disrupt the integrity of the wall around the anchor. It is the recommendation of this author that either hot-dipped galvanized or stainless steel elements be utilized for exterior wall applications to reduce the potential for localized corrosion. Since most repairs of this type are labor intensive, the additional material cost for utilizing such materials is most often negligible with respect to the overall project costs.

A fundamentally important component of any such repair program involves the verification of the design assumptions in the exisiting materials through quality assurance testing of the repairs. Depending on the repair approach and the condition of the existing wall and framing system, it is normally recommended that initial material testing of the masonry (brick and mortar) be performed to estimate the anticipated anchor capacity. Additionally, in-situ tensile pull-out tests should be performed on anchors, fasteners and adhesives to verify the capacity as installed is consistent with the design. This is particularly true of epoxy resins that rely on the bond to the in-place materials to achieve the necessary tensile capacity. Tests should be performed in multiple locations with varying existing conditions. Load capacities should be conservatively estimated to account for future weathering of the masonry systems.


The use of lateral anchors to stabilize exterior masonry walls is a relatively inexpensive method of repair if it can be applied before masonry displacement becomes excessive and the walls become unstable. The materials used and the methods employed are easily utilized by most specialty repair contractors. Structurally, the addition of intermediate support conditions is one of the most efficient methods for providing supplemental lateral restraint in a masonry wall, and the existing framing system often provides more than enough support to restrain further movement. By using corrosion resistant components and by performing required maintenance on the floor framing systems and the masonry walls (such as pointing or mortar joints), the repairs can easily extend the service life of a building without the need for major reconstruction or modification of the load bearing systems of the building. Utilizing such an approach is both cost effective and provides a sustainable design methodology for the repairs. By minimizing the removal of the existing masonry, the historic character of the building is preserved, while insuring that such valuable structures stay in service for many years to come.


Reynolds, P., Muurankers – Wall Anchors, Reproduced at http://www.lowlands-l.net/history/reynolds_muurankers.php

Hillman-Crouch, Barry, Historic Ironwork Repairs in Timber Framed Buildings, http://www.dowsingarchaeology.org.uk/Ironwork/iron-index.htm

“Technical Information Note 8 – Installation of Lateral Restraint to External Walls at Pitched Roof Level”, Cheshire West and Chester Building Control Consultancy, March 2009