Which type of aluminum is most often used in architectural sheet-metal work?

• A. Soft
• B. Half hard
• C. Annealed
• D. Alloyed

Answer: (B)

Architectural sheet metal needs a balance between formability and stiffness so panels and seams hold their shape under weather and wind. Half-hard is the right choice because it’s been work-hardened enough to increase strength and dent resistance, yet still flexible enough to form bends and seams without cracking. Soft or annealed aluminum is very easy to form but too soft to maintain shape and resist dents in exposed use. Alloyed describes the metal’s composition rather than its hardness or forming state, so it’s not addressing the practical need for a workable yet rigid sheet in architecture.