Stone anchor testing employed as a method of confirming an engineered design or a prescriptive, non-engineered system is critical in the increasingly complex construction market where many different subcontractors are responsible for fragments of a given wall. Project specific stone anchor testing not only provides a documented measurement of performance, but also can give some peace-of-mind to the installer, as well as the design and development teams.

For purposes of this discussion, it is important to first establish a logical definition for a stone anchor.

Webster defines an anchor as “Something that provides a rigid point of support…” or “Something that provides stability or security.”Anchorage is “A means of stabilizing and securing.”

The 2006 International Building Code (IBC) defines anchored masonry veneer as “Veneer secured with approved mechanical fasteners to an approved backing.”

All these definitions are vague and subjective, but there is a one common theme: security.

Security is defined as “Freedom from risk or danger; safety.”

Secure is defined as “Safe; not likely to fail or give way; stable; firmly fastened.”

These definitions help clarify the intent of the building code and provide qualitative criteria for design and installation. The idea of security is what stone testing is all about.

The big question

With regard to slab-type stone veneer, what are anchors? The qualitative criteria provided in the very definition of “secure” can be used as a basis to assess different materials and methods used in the installation of stone veneer:

  • Safe
  • Not likely to fail or give way
  • Stable
  • Firmly fastened.

Take a short drive in most U.S. cities and many of the following devices will be found on both residential and commercial jobsites used as anchors for slab-type stone veneer. Are all these devices appropriate for dimensional or slab-type stone anchorage?

Let's weigh the pros and cons of each and then answer the important question: “Does it meet the ‘secure' criteria?”

Corrugated wall tie

Pros: Easy to install; intended for modular brick.

Cons: No mechanical engagement to stone; ability to accommodate imposed loads dependent on bond strength of mortar to stone; typically minimal capacity to transfer loads from the veneer to the substrate; corrosion resistance; not appropriate for slab-type veneer.

This product does not meet current building code minimum requirements for slab-type veneer (2006 IBC, Section 1405.7).

Material and installation cost: $

Secure: No, loss or lack of development of mortar bond to stone effectively allows stone units to move independently without a restraint in any direction. No redundancy of support or restraint.

Adjustable wall tie

Pros: Adjustable; can accommodate vertical movement; triangle or vee available in varying sizes, diameters, and finishes; intended for modular brick.

Cons: No mechanical engagement to stone; ability to accommodate imposed loads dependent on bond strength of mortar to stone; corrosion resistance; not appropriate for slab-type veneer.

This type of anchor does not meet current building code minimum requirements for slab-type veneer (2006 IBC, Section 1405.7).

Material and installation cost: $

Secure: No, loss or lack of development of mortar bond to stone effectively allows stone units to move independently without a restraint in any direction. No redundancy of support or restraint.