2. The general subject of sheet-metal work for roof coverings, flashings, etc., has been treated in the section on Roofing, and the application of sheet-metal work for ventilating purposes is dealt with in the section on Heating and Ventilation ; consequently this portion of the subject will not be considered in this section.

3. The kind and class of exterior sheet-metal work required, will of course depend upon the character and purpose of the building. Mills, factories, workshops, warehouses, etc. are often covered with galvanized sheet iron in the plainest possible manner, with no pretensions to artistic treatment, while store and office fronts are often covered with sheet metal bent and formed into elaborate moldings, or pressed and stamped into ornamental details, which are grouped so as to form decorative features. Generally speaking, sheet-metal coverings for buildings are imitations of brickwork or masonry, and when properly arranged and attached to a good solid backing and carefully painted, they make, for some time, successful deceptions.

Sheet-metal fronts and other wall coverings are employed only when the desire for ornamentation exceeds the owner's willingness or capability to pay for the genuine article. From a speculative point of view they may be paying investments, providing the metal is protected against corrosion; but from an architectural or engineering standpoint, they are utter failures.