Recent studies show that horizontal joint reinforcement can perform as structural reinforcement too. When properly placed and bonded in a mortar joint it can: carry loads in the horizontal direction; replace intermediate bond beams; and increase the load capacity of a shear wall. Joint reinforcement also can reinforce stack bond masonry, tie masonry wythes together in composite and cavity walls, and connect intersecting walls. PREFABRICATED JOINT REINFORCEMENT Joint reinforcement is prefabricated in ladder and truss configuration. Either plain or deformed cold-drawn steel wire is used to make the ready-to-use reinforcement. The longitudinal wires of the reinforcement should be at least 9 gauge but not more than one-half the thickness of the bed joint. Most manufacturers classify joint reinforcement as standard, medium, and heavy according to the diameter of the longitudinal wires. MULTIWYTHE WALLS For cavity or composite walls, prefabricated joint reinforcement can be made with integral wall ties. Such reinforcement performs two functions: It reinforces the backup wythes of the cavity or composite wall and it ties the two wythes together. Only ladder-type joint reinforcement should be used in cavity walls. Truss-type reinforcement used in most projects is made of galvanized steel wire, but stainless or fusion-bonded, epoxy-coated steel wires are available for walls subject to corrosive environments. INSTALLING THE REINFORCEMENT Joint reinforcement should be laid on the bare masonry, before placing mortar, with the longitudinal wires centered over each face shell. Then place mortar over the face shells and the reinforcement.
