Parapet
From Wikipedia, the free encyclopedia
A parapet consists of a barrier at the edge of a structure employed to prevent persons or vehicles from falling over the edge.
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[edit] Building parapets
A building parapet consists of a dwarf wall along the edge of a roof, or round a lead flat, terrace walk, etc., to prevent persons from falling over, and as a protection to the defenders in case of a siege. The word comes from the Italian parapetto and/or the French parapet, from Italian para, imperative of Italian parare (to cover, defend) and petto (breast), ultimately from the Latin pectus (breast); the Germans use the term Brustwehr (lit. chest protection), and in Norwegian brystvern which means the same, probably just a translation of the German term.
Parapets are either plain, embattled, perforated or panelled. The last two are found in all styles except the Romanesque.
- Plain parapets are simply portions of the wall generally overhanging a little, with a coping at the top and corbel table below.
- Embattled parapets are sometimes panelled, but more often pierced for the discharge of arrows, etc.
- Perforated parapets are pierced in various devices as circles, trefoils, quatrefoils and other designs so that the light is seen through.
- Panelled parapets are those 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.
[edit] Parapet roofs
Parapets surrounding roofs are extremely common in London. This dates from the Building Act of 1707 which banned projecting wooden eaves in the cities of Westminster and London as they were considered 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.
[edit] Bridge parapets
Parapets are used on bridges and other highway structures (such as retaining walls) to prevent vehicles, and other users such as pedestrians, cyclists and horse riders, from falling where there is a vertical or near-vertical drop. In addition, parapets may be designed to restrict views, prevent debris passing onto traffic below, and 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".
[edit] References
- This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
