EngineeringExpansion, Flatness & Thermal Conductivity

Thermal Expansion

While the concept of thermal expansion is well understood among architects and engineers, occasionally there are problems relating to insufficient thermal expansion allowances.

If expansion joints are not properly located or fastening points for metal panels do not allow linear expansion, permanent damage can occur to the panel work that otherwise has nowhere to go as it expands. This damage comes in the form of buckled and undulated surfaces that are the result of panel sections colliding with each other.

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Thermal Conductivity

Thermal conductivity of architectural metals used to clad the exteriors of buildings is a significant factor in energy efficiency. The purpose of insulating materials is to limit the transfer of heat in or out of the structures, so as to maintain a comfortable temperature at a reasonable cost. 

Popular cladding materials like aluminum, copper and carbon steel are very efficient conductors of heat. They depend upon insulation to create an energy efficient system, be it a roof or an exterior wall. However, if less thermally conductive metals are used, the insulation layer has less work to do, and the energy efficiency of the building system will be improved.

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Flatness of Sheet Metal

Metal flatness is a big issue in architectural panel work. If the incoming material has errant shape, the panel manufacturer or fabricator cannot avoid producing a panel that exhibits oil canning (repeating undulations in the panel surface), concave or convex profiles or buckles at the corners. 

Architects and building owners have been more or less forced to accept these conditions since ASTM standards allow sufficient shape deviation to create these visual disturbances. Most sheet metal applications do not require superb flatness (stamped parts, welded tubes, industrial equipment, ect.) Therefore, most commercial products available on the market have enough shape deviation to result in visually unattractive panels. However, the the extent possible, Contrarian Metal Resources supplies shape corrected material, which has been coil stretched. This gives fabricators the flattest possible incoming material.

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