Defensive walls in fortification
Walls in buildings that form a fundamental part of the superstructure or separate interior sections, sometimes for fire safety
Retaining walls, which hold back dirt, stone, water, or noise sound
Walls that protect from oceans (seawalls or rivers levees)
Permanent, solid fences
Border barriers between countries
Glass wall (only when most of the wall, in smaller amounts it is called a window)
Doors are mobile walls on hinges which open to form a gateway.
Wall comes from Latin vallum meaning "...an earthen wall or rampart set with palisades, a row or line of stakes, a wall, a rampart, fortification..." while the Latin word murus means a defensive stone wall. English uses the same word to mean an external wall and the internal sides of a room, but this is not universal. Many languages distinguish between the two. In German, some of this distinction can be seen between Wand and Mauer, in Spanish between pared and muro.
The purposes of the walls in buildings are to support roofs, floors and ceilings; to enclose a space as part of the building envelope along with a roof to give buildings form; and to provide shelter and security. In addition, the wall may house various types of utilities such as electrical wiring or plumbing. Wall construction falls into two basic categories: framed walls or mass-walls. In framed walls the load is transferred to the foundation through posts, columns or studs. Framed walls most often have three or more separate components: the structural elements (such as 24 studs in a house wall), insulation, and finish elements or surfaces (such as drywall or panelling). Mass-walls are of a solid material including masonry, concrete including slipform stonemasonry, log building, cordwood construction, adobe, rammed earth, cob, earthbag construction, bottles, tin cans, straw-bale construction, and ice.
There are three basic methods walls control water intrusion: moisture storage, drained cladding, or face-sealed cladding. Moisture storage is typical of stone and brick mass-wall buildings where moisture is absorbed and released by the walls of the structure itself. Drained cladding also known as screened walls acknowledges moisture will penetrate the cladding so a moisture barrier such as housewrap or felt paper inside the cladding provides a second line of defense and sometimes a drainage plane or air gap allows a path for the moisture to drain down through and exit the wall. Sometimes ventilation is provided in addition to the drainage plane such as in rainscreen construction. Face-sealed also called barrier wall or perfect barrier cladding relies on maintaining a leak-free surface of the cladding. Examples of face sealed cladding are the early exterior insulation finishing systems, structural glazing, metal clad panels, and corrugated metal.
Building walls frequently become works of art, externally and internally, such as when featuring mosaic work or when murals are painted on them; or as design foci when they exhibit textures or painted finishes for effect.