facade material
The primary material(s) of a structure's exterior surface, except for windows.
The facade material of any built object is any substance which forms a significant portion (at least 10%) of its outward-facing surface, not including windows, doorways, or openings. More than one facade material may be assigned, as long as each one constitutes at least ten percent of the facade surface area.
Facade materials do not include any underlying or hidden material such as insulation or structural walls, unless those are exposed to the outside. They may, however, be covered by paint, varnish, or very thin protective coatings. Very thin coatings on a facade are not considered facade materials themselves, although thick coatings like stucco are.
Glass is only considered a facade material if it covers something opaque, such as a column, spandrel, or wall. Windows are not considered part of the facade for purposes of this definition.
The actual arrangement or form of facade materials is described separately by the facade system. Built objects can also be classified according to facade color.
