From en.wikipedia.org:
[Barrier extending upward a wall at the edge of a roof] A PARAPET is a barrier
that is an upward extension of a wall at the edge of a roof,<ref
name=EB1911>[wstitle=Parapet ] 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.[1] 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,[2] and to prevent the spread of fires.
** Parapet types
Parapets may be plain, embattled, perforated or panelled,<ref name=EB1911/>
which are not mutually exclusive terms.
- Plain parapets are upward extensions of the wall, sometimes with a coping at the top and corbel below. <ref name=EB1911/>
- 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 circle s, trefoil s, or quatrefoil s. <ref name=EB1911/>
- 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. <ref name=EB1911/>
<gallery mode=packed> File:Rooftop pool NYC.jpg|A parapet surrounds a New York
City 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 </gallery>
** Historic parapet walls
The Mirror Wall at Sigiriya, Sri Lanka 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 [250] and
provided protection from inclement weather. Only about [100] 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.[3]
** Parapet roofs
Parapets surrounding roofs are common in London. This dates from the Building
Act 1707 which banned projecting wooden eaves in the cities of Westminster and
London as a fire risk.[date=October 2015] 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.[4] 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 < !-- this section is linked from many pages on Wikipedia & Commons, do not change name without leaving an anchor -->
Parapets on bridges and other highway structures (such as retaining walls)
prevent users from falling off where there is a drop.<ref
name=flickr>[url=https://www.flickr.com/photos/tlehman/340735047/in/photostream/]
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.<ref name=flickr/>
In European standards, parapets are defined as a sub-category of "vehicle
restraint systems" or "pedestrian restraint systems".
** Parapets in fortification
[parapet_parts.svg] 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.[5][6] In medieval castles, 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_.[7]
** See also
- Attic style
- Baluster
- Merlon
- Redoubt
** References
[Reflist]
** Bibliography
- Senani Ponnamperuma (2013). _The Story of Sigiriya_ . Panique Pty Ltd. pp. 124–127, 179.. [978-0987345141] .
** External links
[Wiktionary] [Parapets]
- Victorian Forts glossary (see http://www.victorianforts.co.uk/gloss.htm) [url=https://web.archive.org/web/20160304024157/http://www.victorianforts.co.uk/gloss.htm ]
- Parapet (see https://web.archive.org/web/20070124061217/http://freenet.buffalo.edu/bah/a/DCTNRY/p/parapet.html)
- What is a Parapet? (see http://architecture.about.com/library/blgloss-parapet.htm) [url=https://web.archive.org/web/20090201005917/http://architecture.about.com/library/blgloss-parapet.htm ]
[Authority control]
Category:Castle architecture Category:Architectural elements Category:Bridge
components Category:Protective barriers