Pure copper. Unlike other metals, copper is frequently used in its pure (99.9% Cu) unalloyed form for sheet and strip applications in roofing, exterior cladding, and flashing.
Tempering is a heat treatment technique used to increase the toughness of metals. Tempers determine the ductility of the metal, and therefore how well it forms and will hold its shape without additional support. In the U.S., copper is available in six tempers: 060 soft,  hard cold rolled,  cold rolled high yield, half hard, three quarter hard, and hard. In the U.K., only three designations exist: soft, half-hard, and hard. Copper and its alloys are defined in the U.S. in Standard Designations for Copper and Copper Alloys by ASTM; in Europe by BS EN 1172: 1997 - Copper and Copper Alloys in Europe; and in the U.K. by the British Standard Code of Practice CP143: Part12: 1970.
Cold rolled copper temper is by far the most popular in building construction in the U.S. It is less malleable than soft copper but is far stronger. Cold rolled  hard tempered copper is often recommended for roofing and flashing installations. Roof sheets with higher tempers may be specified for certain applications.
Soft tempered copper is extremely malleable and offers far less resistance than cold rolled copper to the stresses induced by expansion and contraction. It is used for intricate ornamental work and where extreme forming is required, such as in complicated thru-wall flashing conditions.
The major use for high-yield copper is in flashing products, where malleability and strength are both important.
The thickness of sheet and strip copper is measured in the U.S. by its weight in ounces per square foot. Thicknesses commonly used in construction in the U.S. are between  and . Since the industry often uses gauge numbers or actual thicknesses for sheet metal or other building materials, it is necessary to convert between the different measurement systems.
In Europe, phosphorus de-oxidized non-arsenical copper is used with the designation C106. The copper is rolled to thicknesses ranging between  ( for curtain walling) but a  thickness is usually used for roofing.
Alloyed copper. Copper alloys, such as brass and bronze, are also used in residential and commercial building structures. Variations in color stem primarily from differences in the alloy chemical composition.
Some of the more popular copper alloys and their associated Unified Numbering System (UNS) numbers developed by ASTM and SAE are as follows:
In practice, the term bronze may be used for a variety of copper alloys with little or no tin if they resemble true bronzes in color.
Further information on architectural copper alloys is available.