A roof is part of a building envelope. It is the covering on the uppermost part of a building or shelter which provides protection from animals and weather, notably rain or snow, but also heat, wind and sunlight. The word also denotes the framing or structure which supports that covering. The characteristics of a roof are dependent upon the purpose of the building that it covers, the available roofing materials and the local traditions of construction and wider concepts of architectural design and practice and may also be governed by local or national legislation. In most countries a roof protects primarily against rain. A verandah may be roofed with material that protects against sunlight but admits the other elements. The roof of a garden conservatory protects plants from cold, wind, and rain, but admits light.
A roof may also provide additional living space, for example a roof garden.
1 Etymology 2 Design elements 3 Form 4 Parts
4.1 Support 4.2 Outer layer
5.1 Insulation 5.2 Drainage 5.3 Solar roofs
6 Gallery of roof shapes 7 Gallery of significant roofs 8 References
Etymology Old English hrof "roof, ceiling, top, summit; heaven, sky," also figuratively, "highest point of something," from Proto-Germanic *khrofam (cf. Dutch roef "deckhouse, cabin, coffin-lid," Middle High German rof "penthouse," Old Norse hrof "boat shed"). There are no apparent connections outside the Germanic family. "English alone has retained the word in a general sense, for which the other languages use forms corresponding to OE. þæc thatch" [OED]. Design elements The elements in the design of a roof are:
the material the construction the durability
The material of a roof may range from banana leaves, wheaten straw or seagrass to laminated glass, copper (see: copper roofing), aluminium sheeting and pre-cast concrete. In many parts of the world ceramic tiles have been the predominant roofing material for centuries, if not millennia. Other roofing materials include asphalt, coal tar pitch, EPDM rubber, Hypalon, polyurethane foam, PVC, slate, Teflon fabric, TPO, and wood shakes and shingles. The construction of a roof is determined by its method of support and how the underneath space is bridged and whether or not the roof is pitched. The pitch is the angle at which the roof rises from its lowest to highest point. Most US domestic architecture, except in very dry regions, has roofs that are sloped, or pitched. Although modern construction elements such as drainpipes may remove the need for pitch, roofs are pitched for reasons of tradition and aesthetics. So the pitch is partly dependent upon stylistic factors, and partially to do with practicalities. Some types of roofing, for example thatch, require a steep pitch in order to be waterproof and durable. Other types of roofing, for example pantiles, are unstable on a steeply pitched roof but provide excellent weather protection at a relatively low angle. In regions where there is little rain, an almost flat roof with a slight run-off provides adequate protection against an occasional downpour. Drainpipes also remove the need for a sloping roof. A person that specializes in roof construction is called a roofer. The durability of a roof is a matter of concern because the roof is often the least accessible part of a building for purposes of repair and renewal, while its damage or destruction can have serious effects. Form
Terminology of some roof parts
Main article: List of roof shapes The shape of roofs differs greatly from region to region. The main factors which influence the shape of roofs are the climate and the materials available for roof structure and the outer covering. The basic shapes of roofs are flat, mono-pitched, gabled, hipped, butterfly, arched and domed. There are many variations on these types. Roofs constructed of flat sections that are sloped are referred to as pitched roofs (generally if the angle exceeds 10 degrees). Pitched roofs, including gabled, hipped and skillion roofs, make up the greatest number of domestic roofs. Some roofs follow organic shapes, either by architectural design or because a flexible material such as thatch has been used in the construction. Parts
Star-roof lifted into the
There are two parts to a roof, its supporting structure and its outer skin, or uppermost weatherproof layer. In a minority of buildings, the outer layer is also a self-supporting structure. The roof structure is generally supported upon walls, although some building styles, for example, geodesic and A-frame, blur the distinction between wall and roof. Support Main article: Domestic roof construction
The roof of a library in Sweden
The supporting structure of a roof usually comprises beams that are
long and of strong, fairly rigid material such as timber, and since
the mid-19th century, cast iron or steel. In countries that use bamboo
extensively, the flexibility of the material causes a distinctive
curving line to the roof, characteristic of Oriental architecture.
A bark roof in Korea. See also: Birch-bark roof
Main article: List of commercially available roofing material
This part of the roof shows great variation dependent upon
availability of material. In vernacular architecture, roofing material
is often vegetation, such as thatches, the most durable being sea
grass with a life of perhaps 40 years. In many Asian countries bamboo
is used both for the supporting structure and the outer layer where
split bamboo stems are laid turned alternately and overlapped. In
areas with an abundance of timber, wooden shingles and boards are
used, while in some countries the bark of certain trees can be peeled
off in thick, heavy sheets and used for roofing.
The 20th century saw the manufacture of composition asphalt shingles
which can last from a thin 20-year shingle to the thickest which are
limited lifetime shingles, the cost depending on the thickness and
durability of the shingle. When a layer of shingles wears out, they
are usually stripped, along with the underlay and roofing nails,
allowing a new layer to be installed. An alternative method is to
install another layer directly over the worn layer. While this method
is faster, it does not allow the roof sheathing to be inspected and
water damage, often associated with worn shingles, to be repaired.
Having multiple layers of old shingles under a new layer causes
roofing nails to be located further from the sheathing, weakening
their hold. The greatest concern with this method is that the weight
of the extra material could exceed the dead load capacity of the roof
structure and cause collapse. Because of this, jurisdictions which use
Tiled roof, Kannur, India.
Terracotta tiles, Hungary
Thatch, using rice straw, Japan
Metal sheeting, Namibia
repairing thatch, Gassho-zukuri farmhouse, Japan
Stone used as roofing material in Himachal Pradesh, India
Turf roof in Norway
Because the purpose of a roof is to protect people and their
possessions from climatic elements, the insulating properties of a
roof are a consideration in its structure and the choice of roofing
Some roofing materials, particularly those of natural fibrous
material, such as thatch, have excellent insulating properties. For
those that do not, extra insulation is often installed under the outer
layer. In developed countries, the majority of dwellings have a
ceiling installed under the structural members of the roof. The
purpose of a ceiling is to insulate against heat and cold, noise, dirt
and often from the droppings and lice of birds who frequently choose
roofs as nesting places.
Concrete tiles can be used as insulation. When installed leaving a
space between the tiles and the roof surface, it can reduce heating
caused by the sun.
Forms of insulation are felt or plastic sheeting, sometimes with a
reflective surface, installed directly below the tiles or other
material; synthetic foam batting laid above the ceiling and recycled
paper products and other such materials that can be inserted or
sprayed into roof cavities. So called Cool roofs are becoming
increasingly popular, and in some cases are mandated by local codes.
Cool roofs are defined as roofs with both high reflectivity and high
Poorly insulated and ventilated roofing can suffer from problems such
as the formation of ice dams around the overhanging eaves in cold
weather, causing water from melted snow on upper parts of the roof to
penetrate the roofing material. Ice dams occur when heat escapes
through the uppermost part of the roof, and the snow at those points
melts, refreezing as it drips along the shingles, and collecting in
the form of ice at the lower points. This can result in structural
damage from stress, including the destruction of gutter and drainage
The primary job of most roofs is to keep out water. The large area of
a roof repels a lot of water, which must be directed in some suitable
way, so that it does not cause damage or inconvenience.
Insulation, drainage and solar roofing
The flat roofs of the Middle East, Israel
Steeply pitched, gabled roofs in Northern Europe
The overhanging eaves of China
Solar roofs Newer systems include solar shingles which generate electricity as well as cover the roof. There are also solar systems available that generate hot water or hot air and which can also act as a roof covering. More complex systems may carry out all of these functions: generate electricity, recover thermal energy, and also act as a roof covering. Solar systems can be integrated with roofs by:
integration in the covering of pitched roofs, e.g. solar shingles. mounting on an existing roof, e.g. solar panel on a tile roof. integration in a flat roof membrane using heat welding, e.g. PVC. mounting on a flat roof with a construction and additional weight to prevent uplift from wind.
Gallery of roof shapes
Sateri roof (with vertical break in pitch), Sweden
Mansard roof, county jail, Mount Gilead, Ohio
Flat roof, house, Western Australia
Round flat roof with overhang, Münster, Germany
Graded roof with a spared spot used as a roof garden, Münster
Gallery of significant roofs
The polychrome tiles of the Hospices de Beaune, France.
The glazed ceramic tiles of the Sydney Opera House.
The dome over the mihrab of the Great Mosque of Kairoun, Tunisia
Imbrex and tegula
The marble dome of the Taj Mahal.
The copper roof of Speyer Cathedral, Germany.
The lead roof of King's College Chapel, England.
The glass roof of the Grand Palais, Paris.
Automobile roof Bituminous waterproofing Roofing felt Tensile architecture Tented roof Thin-shell structure
List of Greco-Roman roofs
^ Whitney, William Dwight, and Benjamin E. Smith. The Century
dictionary and cyclopedia, vol 6. New York: Century Co., 1901. 5,221.
^ C.M.Harris,Dictionary of Architecture & Construction
Wikimedia Commons has media related to Roofs.
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Rooms and spaces of a house
Shared residential rooms
Dirty kitchen Kitchenette
Living room Man cave Recreation room Shrine Study Sunroom
Atrium Balcony Breezeway Catio Conversation pit Deck Elevator Entryway / Genkan Foyer Hallway Lanai Loft Loggia Overhang Patio Porch
Ramp Secret passage Stairs Terrace Veranda Vestibule
Utility and storage
Antechamber Ballroom Butler's pantry Buttery Conservatory Courtyard Drawing room Fainting room Great chamber Great hall Long gallery Lumber room Parlour Porte-cochère Saucery Sauna Scullery Servants' hall Servants' quarters Smoking room Solar Spicery State room Still room Swimming pool Undercroft
Arch Baluster Ceiling Colonnade Column Floor Gate Lighting Medallion Ornament Portico Roof Vault
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