Soffit

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 30 cm wide and made from center lanced U groove perforated sections of vinyl in a return fashion and fixed to a truss roofing system.

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 an arch or architrave (whether supported by piers or columns),
• 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.

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.

In recording studios, historically, monitor speakers were either soffit mounted, i.e. attached to the wall, tight to the underside of the ceiling, or free standing. Mounted to the ceiling, the speaker radiates into quarter-space (π/2 steradians), and so achieves greater efficiency than its free-standing equivalent. The nomenclature has since been habitually used to denote any arrangement where the loudspeaker radiates into less than full space, most notably including flush mounting the speaker into a false wall constructed specifically for the purpose,to radiate into half-space (π steradians). The term 'speaker walls', or, as these walls are invariably built at an angle, simply 'flares' is preferable, particularly when discussing their construction with a builder, who will assume, when one says 'soffit' one means the ceiling, or the lower face of a beam.

References

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.