Shelf Angles for Masonry Veneer

Abstract

Inadequacies of design, construction, and maintenance associated with shelf angles supporting masonry veneer on structural frames often cause spalling, cracking, and staining of masonry veneer; yielding and slipping of shelf angles; and leakage of wind‐driven rain, which in turn causes corrosion; volume change of materials; freeze‐thaw damage; destructive cryptofluorescence; increased heat transmission; deterioration of interior finishes and building contents; tenant inconvenience; and litigation. In the absence of an expansion joint between the horizontal leg of the shelf angle and the top of the masonry below the angle, differential movement between the building frame and the masonry veneer may lift the shelf angle vertically in a wedge insert in a concrete frame. Mortar rather than sealant in the joint at the toe of the shelf angle and improper shimming of the angle often result in spalled masonry. Shelf angle corrosion may be accelerated by inadequacies in masonry construction, condensation due to exfiltration of interior air, and improper angle protection. Dimension of masonry overhang beyond the toe of the shelf angle is critical.