Soffit

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 trusses over the exterior of supporting walls, is the underside of eaves (to connect a supporting wall to projecting edge(s) of the roof).

The term soffit is from Italian: soffitto, formed as a ceiling; and directly from suffictus for suffixus, Latin: suffigere, to fix underneath).

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).

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.

Eaves of a house in Northern Australia . The white underside would be referred to as a soffit. In this example the soffit is fixed to the slope of the rafters . The dark grey fascia boards form the outer edge and have a groove to receive the soffit lining sheets which cover the rafter tails.
Boxed in soffit on a house in Northern Florida , United States. In this example the soffit material is 12 inches wide and made from center lanced U groove perforated sections of vinyl in a return fashion and fixed to the bottom chord of a truss roofing system extending beyond the exterior wall.