- Question: How should shelf angles be treated at outside corners? Is it necessary to extend the shelf angles around the corner, and if so, should they be mitered or coped?
Answer: Shelf angles supporting the masonry wall should extend around the corner. If this is not done the horizontal expansion joint below the shelf angle may be bridged at these locations. If the expansion joint is bridged at the corner, cracking or spalling of the brick units in the corner immediately above or below this angle can result.
Extending the shelf angle to the corner provides support not only for the masonry units, but also for the flashing. This approach facilitates the installation of the flashing at the corners. Many flashing problems occur as a result of poorly formed flashings at corners.
Shelf angles are coped or mitered. Coping the back leg of the shelf angle so that the outstanding leg can be extended to the corner is probably the most common approach to dealing with this condition. The angles on either side of the corner must be adjusted properly so that the projecting legs at this intersection are lined up and are both perpendicular to the face of the wall so that the flashing and units will lie on them properly.