Technically classed as a masonry-bonded hollow wall, utility walls are a regional specialty. Although seldom seen elsewhere, utility walls have been used to construct buildings in North Carolina for more than 30 years. Utility walls are built with nominal 4x4x12 brick, commonly known as utility, jumbo 12, or jumbo utility brick. The major difference between a utility wall and a typical brick cavity wall, however, is the bonding method employed. Most brick cavity walls use metal ties to bond brick wythes, but utility walls are bonded with masonry headers. The most common bond pattern used in utility walls is a variation of Flemish bond, where headers are placed in every sixth course. Utility walls provide a finished surface on both sides; a cavity to contain plumbing, electrical wiring, and insulation; a 4-hour fire rating; excellent moisture resistance; and good acoustical performance. WHY A UTILITY WALL? Why build a utility wall when cavity walls with metal ties seem to fill the same needs? There are several reasons: 1. To avoid the rust and corrosion problems sometimes associated with metal wall ties. 2. Because the wythes of a utility wall are joined by a solid masonry bond, the wall is assumed to act compositely and has greater strength in bending. 3. Building codes often allow utility walls a higher ratio of unsupported height (or length) to thickness than brick cavity walls using metal ties. UTILITY WALL LIMITATIONS Though they're economical when used appropriately, utility walls, like everything else, have their limitations: 1. Utility walls perform best when used as load-bearing walls or as curtain walls. 2. Expansion joints must be closely spaced to accommodate differential movement between the inner and outer wythes. 3. Headers are vulnerable to impact damage in some applications. 4. Architects accustomed to standard brick are sometimes reluctant to use utility brick because of its size. 5. Brick laying speed is reduced because the two wythes must remain parallel during construction.