Architectural copper is a living material. Its bright, reddish surface reacts immediately to its environment, turning first dark brown and finally the characteristic blue-green (patina).
Oxidation is not a defect but the material's self-protection mechanism. On contact with oxygen, a layer of copper oxide forms first (brown/anthracite colour). Over time, sulphur dioxide and air humidity transform the oxide into basic copper sulphates and carbonates (brochantite and malachite). In an urban atmosphere this process takes about 10–15 years, while in a marine environment the timescale roughly halves.
Owing to its high thermal expansion, copper roofing must be installed using standing-seam techniques with sliding clips. Moreover, copper is an extremely noble (cathodic) metal: rainwater running across it becomes enriched with copper ions and can trigger lethal galvanic corrosion if it drips onto zinc, galvanised steel or aluminium elements positioned lower down.
Copper surfaces have intrinsic bactericidal and virucidal properties (contact killing), eliminating pathogens within a few hours. This makes them ideal for handles, handrails and high-touch details in healthcare or public settings.
Standards
European and international references applicable.
Physical properties
Usage environment
In urban atmospheres full patination takes 10-15 years; in marine environments the timescale is halved. The surface has an intrinsic bactericidal action (Contact Killing), ideal for healthcare and public settings. The high thermal conductivity requires insulating copper in construction details to avoid thermal bridges towards the building interior.