I have been told that a minimum of 18 gauge should be used for steel studs in a brick veneer system. In many cases, however, a 20 gauge or 22 gauge stud may work structurally.
Is this 18 gauge figure the industry standard? If so, what is the reason for this recommendation?
The Brick Industry Association provides this recommendation in Technical Note 28B, which states "Steel studs should be a minimum of 0.043 in. (1.1 mm) thick steel or 18 gauge to provide sufficient thickness to engage the threads of the screw."
Screw pull-out strength is typically the weak structural link in these veneer systems. The screws are an essential part of the connection between the brick veneer and the structural backup. The pull-out strength of the screws is a function of the steel stud’s gauge. Using a heavier gauge stud increases the capacity of the pull out of the screws and increases the strength of the whole tie assembly.
I have investigated projects where studs as thin as 22 or 24 gauge have been used. In at least one of these projects, nearly half of the screws installed into the studs were stripped upon installation. The pull-out strength in studs thinner than 18 gauge is not only much lower than 18 gauge, but the values are highly variable.
The stud should be a minimum of 18 gauge and should be coated with a minimum protection of G90/Z275 hot dip galvanized per ASTM A 653/A 653M, or with comparable zinc iron or zinc aluminum alloy coatings. The G60 coatings commonly provided in steel studs do not provide sufficient long-term protection against corrosion and should not be used in brick veneer systems over steel stud backups.