Which type of masonry wall typically does not require a backup wall?

A single-wythe wall is constructed using a single layer of masonry units, which means it does not have a backup or supporting wall behind it. This design can be employed for both structural support and aesthetic purposes, as the wall itself is built thick enough to provide adequate stability without needing an additional wall for support.

In contrast, a double-wythe wall consists of two layers of masonry units, which usually includes an air space or insulation in between the two layers. This design inherently requires a backup wall to provide structural integrity and support. Retaining walls, designed to hold back soil or other materials, often require substantial engineering and reinforcement, which typically necessitates a backup structure to manage the lateral pressure exerted by the retained earth. Brick veneer walls are a cladding system that uses a single layer of brick as a façade over a structural frame, thus requiring a backup wall to bear the loads and provide structural support for the entire assembly.

The distinction with single-wythe walls highlights their unique construction method, allowing them to stand independently without the need for additional backing.