Composite masonry walls combine multiple wythes of the same or different masonry materials to create a unified structure. These walls feature wythes that are bonded together either through mortar-filled collar joints, grouted spaces, or more commonly, with rigid metal ties and reinforcements, with the use of masonry header units being rare. Metal ties are preferred because they effectively minimize water penetration, as these walls primarily absorb moisture and then release it into the atmosphere.
Traditionally, composite walls might mix various materials, such as terra cotta, stone, or facing brick, with internal wythes made of bricks or hollow clay tile, aiming to achieve an optimal balance of appearance, durability, and cost-effectiveness. A classic example is a wall that combines a durable and aesthetically pleasing stone facade with an economical brick inner wythe, using metal ties for bonding. However, modern practices lean towards using uniform masonry types and metal ties over masonry headers for bonding wythes, particularly in load-bearing structures, to ensure consistent structural behavior throughout the wall. An example of this approach is a wall constructed from concrete masonry units for both wythes, bonded with reinforcements, mortar-filled collar joints, and metal ties.
