Why is it that the Brick Institute of America recommends 22-gauge corrugated steel ties to attach brick to wood stud backup, but states that corrugated metal veneer ties should not be used with steel stud backup?
Brick veneer over wood stud backups as described in BIA Technical Notes 28 applies only to buildings limited to three stories in height. This generally would apply to residential buildings, particularly single-family homes. Walls built using these recommendations have performed successfully in residential construction for many years. In taller buildings and those with large expanses of walls, however, wind loads are greater, and masonry walls using flexible anchors are more likely to crack. Corrugated ties are weaker and more flexible than other types of masonry anchors. They are particularly flexible under suction wind loads because the attaching screw or nail generally is offset somewhat from the bend in the tie. This creates an eccentricity that increases the tie's flexibility. In BIA Technical Notes 28B, corrugated ties are not recommended for walls with steel stud backup. Steel stud backup systems are used in commercial structures, and often in buildings taller than three stories. Anchors for these systems should have minimal mechanical play and be relatively stiff. BIA recommends that mechanical play be restricted to between 0.02 and 0.05 inch. The anchors should not deflect more than 0.05 inch under a load of 100 pounds in tension or compression.