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cmu-wallAnchoring and reinforcement are used on every project, whether restoration or new construction. The types of anchors generally are based on the veneer being anchored, the weight of that veneer, the condition of the substrate and challenges that are present when installing the anchors.

Years ago, before the cavity wall, multi-wythe walls were successfully constructed with two to 11 courses of brick, with 11 being the most I have ever seen. While many of them still stand, a header brick used as a wythe tie isn’t recommended. This is due to thermal movement that occurs within the wall. The movement between the wythes of brick can cause some of the header brick to snap, resulting in a wythe-to-wythe tie that takes on different characteristics from when it was constructed.

Though common among older walls, these characteristics demonstrate the importance of selecting the correct wall anchoring and reinforcing for your project. What we have learned from repairing this type of wall has assisted in the development of different types of masonry reinforcing and anchoring.

Wall reinforcing wire has two basic configurations when embedded within a concrete masonry unit (CMU) wall, truss and ladder wire, which have become the standard. Wall wire typically is comprised of a three-wire system. The outer wires usually are larger than the interior wires.

Ladder wire generally is used with vertically reinforced walls. Truss wire normally is not used with walls that are vertically reinforced and grouted, unless specifically specified. Reinforcing wire is available in several commercial types. In locations where moisture is an extreme constant, such as a natatorium, stainless steel wall wire is available.

In exterior walls, hot-dipped galvanized or fusion-bonded epoxy is available. Standard mil-galvanized wall wire is available for interior walls. The use of wall wire with the hook-and-eye pintles allows the contractor who is constructing both the inner and outer masonry to use wythes to reinforce and anchor them in a simple set of steps.

The hook-and-eye design allows for proper veneer anchoring, regardless of whether the bed joints of each wythe align in the same plane. The hook-and-eye allows for differential movement between the different wythes of materials, such as the shrinkage of CMU and the expansive characteristics of brick. This ability to self-adjust stabilizes the cavity wall system for a safe installation, while controlling lateral forces on the veneer. This is an economical use of wall wire, and it hooks to properly support the wall and veneer to provide quality reinforcement for standard construction.

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