Furring

Furring - Strips of wood or metal applied to a wall or other surface to even it, to form an air space, or to give an appearance of greater thickness.
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furring walls - "Furring Out, " means setting off a new wall in front of one already built. This provides for dead air space the extra protection of the surface of the ":furred out" wall.

See also: Scale, Masonry, Bond, Frame, Foundation