From Sigmat

Design Life Prediction: For light steel framing in a ‘warm frame’ environment, design life predictions are in excess of 250 years.
NHBC: NHBC and other housing warranty providers require a design life in excess of 60 years, and accept the use of light gauge steel construction. 
Protection: Light steel sections are protected from corrosion by continuous hot-dip zinc coating. 
Shape: Steel does not shrink, warp or change shape.
Usage: Light steel construction can be used for walls, floors, roofs, suspended ground floors. 
Deterioration: Galvanized steel does not suffer from fungal or biological deterioration and is not susceptible to insect infestation.
Roof Constructions: Even in un-insulated roof constructions, light steel sections provide a design life in excess of 100 years.