Eaves or Soffit lining on a house in Northern Australia. The flat section (underside) would be referred to as a soffit. In this example the soffit is fixed to the slope of the rafters. The fascias form the outer edge and have a groove in them to receive the soffit lining sheets.
Soffit lining a house in Northern Florida, USA. In this example the soffit is 12 inches wide and made from center lanced U groove perforated sections of vinyl in a return fashion and fixed to a truss roofing system.
Soffit box providing a level mounting plane for kitchen ventilation hoods.
Soffit (from French: soffite, formed as a ceiling; directly from suffictus for suffixus, Latin: suffigere, to fix underneath), in architecture, describes the underside of any construction element. Examples of soffits include:
the underside of a flight of stairs, under the classical entablature,
the underside of a projecting cornice, or side of chimney
the underside of a ceiling to fill the space above the kitchen cabinets, at the corner of the ceiling and wall,
the exposed undersurface of any exterior overhanging section of a roof eave.
the wall into which loudspeakers are mounted in a recording studio.
a drop-down box used to mount a kitchen ventilation hood under a sloped or high ceiling.
In popular use, soffit most often refers to the material forming a ceiling from the top of an exterior house wall to the outer edge of the roof, i.e., bridging the gap between a home's siding and the roofline, otherwise known as the eaves. When so constructed, the soffit material is typically screwed or nailed to rafters known as lookout rafters or lookouts for short.
Soffit exposure profile (from wall to fascia) on a building's exterior can vary from a few centimetres (2-3 inches) to 3 feet or more, depending on construction. It can be non-ventilated or ventilated for cooling non livable attic space.