What role does subframe design play in metal facade structural stability?

Subframe design is the structural backbone of a metal facade, dictating how loads—wind, seismic, thermal and gravity—are transferred to the primary structure and how panels align and move over time. A well-designed subframe ensures panels remain within allowable deflection limits, preventing visual distortion and connection failure. Key aspects include member sizing and spacing: larger spans or high-wind zones require stiffer rails and reduced clip spacing to limit panel rotation and oil-canning. Connector design (slotted holes, sliding clips) accommodates thermal expansion while maintaining alignment; improperly detailed fixed connections can induce thermal stress and cause buckling or paint cracking. Material compatibility is vital—use corrosion-compatible metals and isolate dissimilar metals with barriers to prevent galvanic action. Subframe attachments to the structure must be engineered for local substrate conditions (concrete anchors, embedded plates, or welded brackets) and account for building tolerances through adjustable brackets that allow fine alignment during installation. Drainage and fire breaking should be integrated; cavities must support ventilation and continuous insulation without compromising structural continuity. For curved or complex geometry, subframes may use tapered or segmented rails to support compound curvature while maintaining panel geometry. Early coordination between facade engineers and structural engineers ensures the subframe solves for load paths without overloading the primary structure. In short, subframe design is the controlling factor in facade stability, long-term performance and appearance; it must be engineered to the project’s load, movement and durability demands.