A parapet is a barrier that is an upward extension of a wall at the edge of a

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 ...

, terrace, balcony, walkway or other structure. The word comes ultimately from the Italian ''parapetto'' (''parare'' 'to cover/defend' and ''petto'' 'chest/breast'). Where extending above a roof, a parapet may simply be the portion of an exterior wall that continues above the edge line of the roof surface, or may be a continuation of a vertical feature beneath the roof such as a fire wall or party wall. Parapets were originally used to defend buildings from military attack, but today they are primarily used as guard rails, to conceal rooftop equipment, reduce wind loads on the roof, and to prevent the spread of fires.

Parapet types

Parapets may be plain, embattled, perforated or panelled, which are not mutually exclusive terms. *Plain parapets are upward extensions of the wall, sometimes with a coping at the top and corbel below. *Embattled parapets may be panelled, but are pierced, if not purely as stylistic device, for the discharge of defensive projectiles. *Perforated parapets are pierced in various designs such as circles, trefoils, or quatrefoils. *Panelled parapets are ornamented by a series of panels, either oblong or square, and more or less enriched, but not perforated. These are common in the Decorated and Perpendicular periods. File:Rooftop pool NYC.jpg, A parapet surrounds a

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

rooftop, shielding the HVAC and water tank and supporting the glass guardrails. File:Kings chapel roof.jpg, Elaborate parapets flank the roof of King's College Chapel, Cambridge. File:BP Bridge (no railing).jpg, A modern parapet with integrated lighting functions as a guard rail along the BP Pedestrian Bridge in Chicago

Historic parapet walls

The Mirror Wall at Sigiriya,

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

built between 477 and 495 AD is one of the few surviving protective parapet walls from antiquity. Built onto the side of Sigiriya Rock it ran for a distance of approximately and provided protection from inclement weather. Only about of this wall exists today, but brick debris and grooves on the rock face along the western side of the rock clearly show where the rest of this wall once stood.

Parapet roofs

Parapets surrounding roofs are common in

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

. This dates from the Building Act 1707 which banned projecting wooden eaves in the cities of Westminster and

as a fire risk. Instead an 18-inch brick parapet was required, with the roof set behind. This was continued in many Georgian houses, as it gave the appearance of a flat roof which accorded with the desire for classical proportions. In Shilpa Shastras, the ancient Indian science of sculpture, a parapet is known as ''hāra''. It is optionally added while constructing a temple. The ''hāra'' can be decorated with various miniature pavilions, according to the Kāmikāgama. In the Bible the Hebrews are obligated to build a parapet on the roof of their houses to prevent people falling (Deuteronomy 22:8).

Firewall parapets

Many firewalls are required to have a parapet, a portion of the wall extending above the roof. The parapet is required to be as fire resistant as the lower wall, and extend a distance prescribed by building code.

Bridge parapets

Parapets on bridges and other

highway A highway is any public or private road or other public way on land. It includes not just major roads, but also other public roads and rights of way. In the United States, it is also used as an equivalent term to controlled-access highway, or ...

structures (such as retaining walls) prevent users from falling off where there is a drop. They may also be meant to restrict views, to prevent rubbish passing below, and to act as noise barriers. Bridge parapets may be made from any material, but structural steel, aluminium, timber and reinforced concrete are common. They may be of solid or framed construction. In European standards, parapets are defined as a sub-category of "vehicle restraint systems" or "pedestrian restraint systems".

Parapets in fortification

A parapet fortification (known as a breastwork when temporary) is a wall of stone, wood or earth on the outer edge of a defensive wall or trench, which shelters the defenders. In medieval

castle A castle is a type of fortification, fortified structure built during the Middle Ages predominantly by the nobility or royalty and by Military order (monastic society), military orders. Scholars usually consider a ''castle'' to be the private ...

s, they were often crenellated. In later artillery forts, parapets tend to be higher and thicker. They could be provided with embrasures for the fort's guns to fire through, and a banquette or fire-step so that defending infantry could shoot over the top. The top of the parapet often slopes towards the enemy to enable the defenders to shoot downwards; this incline is called the ''superior talus''.''A New and Enlarged Military Dictionary'', Charles James, Egerton Military Library 1810.

References

Bibliography

* Senani Ponnamperuma (2013). ''The Story of Sigiriya''. Panique Pty Ltd. pp. 124–127, 179. .

External links

Victorian Forts glossary
{{Authority control Castle architecture Architectural elements Bridge components Protective barriers