The eaves are the edges 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 temper ...

which overhang the face of a wall and, normally, project beyond the side of a building. The eaves form an overhang to throw water clear of the walls and may be highly decorated as part of an architectural style, such as the Chinese

dougong ''Dougong'' () is a structural element of interlocking wooden brackets, one of the most important in traditional Chinese architecture. The use of dougong first appeared in buildings of the late centuries BC and evolved into a structural net ...

bracket systems.

Etymology and usage

According to the ''

Oxford English Dictionary The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...

'', ''eaves'' is derived from the

Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...

(singular), meaning "edge", and consequently forms both the singular and plural of the word. This Old English word is itself of Germanic origin, related to the German dialect ''Obsen'', and also probably to ''over''. The

Merriam-Webster Merriam-Webster, Inc. is an American company that publishes reference books and is especially known for its dictionaries. It is the oldest dictionary publisher in the United States. In 1831, George and Charles Merriam founded the company as ...

dictionary lists the word as ''eave'' but notes that it is "usually used in plural".

Function

The primary function of the eaves is to keep rain water off the walls and to prevent the ingress of water at the junction where the roof meets the wall. The eaves may also protect a pathway around the building from the rain, prevent erosion of the footings, and reduce splatter on the wall from rain as it hits the ground. The secondary function is to control solar penetration as a form of

passive solar building design In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy, in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unli ...

; the eaves overhang can be designed to adjust the building's

solar gain Solar gain (also known as solar heat gain or passive solar gain) is the increase in thermal energy of a space, object or structure as it absorbs incident solar radiation. The amount of solar gain a space experiences is a function of the total in ...

to suit the local climate, the latitude and orientation of the building. The eaves overhang may also shelter openings to ventilate the roof space.

Design

Aesthetic, traditional or purely decorative considerations may prevail over the strictly functional requirements of the eaves. The Arts and Crafts Movement influenced the

American Craftsman American Craftsman is an American domestic architectural style, inspired by the Arts and Crafts movement, which included interior design, landscape design, applied arts, and decorative arts, beginning in the last years of the 19th century. Its ...

tradition, which has very wide eaves with decorative

brackets A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings. Typically deployed in symmetric pairs, an individual bracket may be identified as a 'left' or 'r ...

technically called

modillon A modillion is an ornate bracket, more horizontal in shape and less imposing than a corbel. They are often seen underneath a Cornice (architecture), cornice which it helps to support. Modillions are more elaborate than dentils (literally translat ...

s, for which there is not necessarily a real functional need; likewise the Italian-style eaves. The eaves may terminate in a

fascia A fascia (; plural fasciae or fascias; adjective fascial; from Latin: "band") is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches to, stabilizes, encloses, and separates muscles and other internal organs. ...

, a board running the length of the eaves under the tiles or roof sheets to cap off and protect the exposed rafter ends and to provide grounds on which to fix gutters. At the

gable A gable is the generally triangular portion of a wall between the edges of intersecting roof pitches. The shape of the gable and how it is detailed depends on the structural system used, which reflects climate, material availability, and aesth ...

s the eaves may extend beyond the gable end wall by projecting the

purlin A purlin (or historically purline, purloyne, purling, perling) is a longitudinal, horizontal, structural member in a roof. In traditional timber framing there are three basic types of purlin: purlin plate, principal purlin, and common purlin. Pu ...

s and are usually capped off by

bargeboard Bargeboard (probably from Medieval Latin ''bargus'', or ''barcus'', a scaffold, and not from the now obsolete synonym "vergeboard") or rake fascia is a board fastened to each projecting gable of a roof to give it strength and protection, and to ...

s to protect the wall and the purlin ends. The underside of the eaves may be filled with a horizontal

soffit A soffit is an exterior or interior architectural feature, generally the horizontal, aloft underside of any construction element. Its archetypal form, sometimes incorporating or implying the projection of beams, is the underside of eaves (to ...

fixed at right angles to the wall, the soffit may be decorative but it also has the function of sealing the gap between the rafters from vermin and weather. Eaves must be designed for local wind speeds as the overhang can significantly increase the wind loading on the roof. The line on the ground under the outer edge of the eaves is the

eavesdrip The eavesdrop or eavesdrip is the width of ground around a house or building which receives the rain water dropping from the eaves. By an ancient Anglo-Saxon law Anglo-Saxon law (Old English ''ǣ'', later ''lagu'' "law"; dōm "decree, judgment ...

, or dripline, and in typical building planning regulations defines the extent of the building and cannot oversail the property boundary.

References

External links

* {{Use dmy dates, date=March 2017 Architectural elements Roofs es:Cornisa

Etymology and usage

Function

Design

See also

References

External links