A soffit is an exterior architectural feature, generally the horizontal, aloft underside of the roof edge. Its archetypal form, sometimes incorporating or implying the projection of
rafters or
truss
A truss is an assembly of ''members'' such as Beam (structure), beams, connected by ''nodes'', that creates a rigid structure.
In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so ...
es over the exterior of supporting walls, is the underside of
eaves (to connect a supporting wall to projecting edge(s) of the
roof
A roof (: roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of tempera ...
). The vertical band at the edge of the roof is called a
fascia. A soffit of an
arch
An arch is a curved vertical structure spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC, but stru ...
is frequently called an
intrados.
Etymology
The term ''soffit'' is from , formed as a ceiling; and directly from ''suffictus'' for ''suffixus'', , to fix underneath).
Soffits in homes and offices
In
architecture
Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and construction, constructi ...
, soffit is the underside (but not base) of any construction element.
Examples include:
Under the eaves of a roof
In foremost use ''soffit'' is the first definition in the table above. In spatial analysis, it is one of the two necessary planes of any (3-dimensional) optionally built area,
eaves, which projects, for such area to be within the building's space.
In two-dimensional face analysis it is a discrete face almost always parallel with the ground that bridges the gap(s) between a building's
siding (walls) and either: their parallel extraneous plane (
fascia) where such exists; or where no such plane, a point along (or the abrupt end of) the roof's outer projection (overhang). Soffits and fascias are archetypally screwed or nailed to rafters known as
lookout rafters or ''lookouts'' for short, their repair being often undertaken simultaneously. A parapet wall or cornice tend to preclude eaves, as an alternate design, both favouring flat roofs and weather-proof walls. Very pronounced overhangs (eaves) are characteristic to European architecture to shield the walls from rain, sleet and snow such as
Swiss chalet style,
Dutch,
Romanian, and
Tudor architecture
The Tudor architectural style is the final development of medieval architecture in England and Wales, during the Tudor period (1485–1603) and even beyond, and also the tentative introduction of Renaissance architecture to Britain. It fo ...
.
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, to prevent condensation. A grill that covers the venting opening on the bottom of the soffit is called a soffit vent. A soffit joist can be added to the framework instead of or in addition to lookouts.
References
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{{Authority control
Ceilings
Roofs