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{{For|automobile roofs|Sunroof}} |
{{For|automobile roofs|Sunroof}} |
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[[Image:Churches in Olomouc.jpg|thumb|The roofs of Olomouc, [[Czech Republic]].]][[Image:Vietnam roof.jpg|thumb|The roofs of [[Vietnam]].]] |
[[Image:Churches in Olomouc.jpg|thumb|The roofs of Olomouc, [[Czech Republic]].]] |
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[[Image:Vietnam roof.jpg|thumb|The roofs of [[Vietnam]].]] |
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[[Image:San Cristobal de las Casas.jpg|thumb|The roofs of San Cristobal de las Casas, [[Mexico]].]] |
[[Image:San Cristobal de las Casas.jpg|thumb|The roofs of San Cristobal de las Casas, [[Mexico]].]] |
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A '''roof''' is the covering on the uppermost part of a [[building]]. A roof protects the building and its contents from the effects of [[weather]]. Structures that require roofs range from a [[letter box]] to a [[cathedral]] or [[stadium]], [[dwelling]]s being the most numerous. |
A '''roof''' is the covering on the uppermost part of a [[building]]. A roof protects the building and its contents from the effects of [[weather]]. Structures that require roofs range from a [[letter box]] to a [[cathedral]] or [[stadium]], [[dwelling]]s being the most numerous. |
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In most countries a roof protects primarily against [[rain]]. Depending upon the nature of the building, the roof may also protect against heat, against sunlight, against cold and against wind. Other types of structure, for example, a garden [[Conservatory (greenhouse)|conservatory]], might use roofing that protects against cold, wind and rain but admits light. A [[verandah]] may be roofed with material that protects against sunlight but admits the other elements. |
In most countries a roof protects primarily against [[rain]]. Depending upon the nature of the building, the roof may also protect against heat, against sunlight, against cold and against wind. Other types of structure, for example, a garden [[Conservatory (greenhouse)|conservatory]], might use roofing that protects against cold, wind and rain but admits light. A [[verandah]] may be roofed with material that protects against sunlight but admits the other elements. |
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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]]. |
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]]. |
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The elements in the design of a roof |
The elements in the design of a roof are: |
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* the [[material]] |
* the [[material]] |
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* the [[construction]] |
* the [[construction]] |
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* the [[durability]] |
* the [[durability]] |
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The '''[[material]]''' of a roof may range from [[banana]] leaves, wheaten [[straw]] or [[seagrass]] to [[Architectural glass|lamininated glass]], [[aluminium]] sheeting and [[precast concrete]]. In many parts of the world ceramic [[tiles]] have been the predominant roofing material for centuries. |
The '''[[material]]''' of a roof may range from [[banana]] leaves, wheaten [[straw]] or [[seagrass]] to [[Architectural glass|lamininated glass]], [[aluminium]] sheeting and [[precast concrete]]. In many parts of the world ceramic [[tiles]] have been the predominant roofing material for centuries. |
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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 [[house|domestic architecture]], except in very dry regions, has roofs that are sloped, or ''pitched''. The pitch is partly dependent upon stylistic factors, but has more to do with practicalities. Some types of roofing, for example [[thatch]], require a steep pitch in order to be waterproof and durable.<ref> |
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 [[house|domestic architecture]], except in very dry regions, has roofs that are sloped, or ''pitched''. The pitch is partly dependent upon stylistic factors, but has more to do with practicalities. Some types of roofing, for example [[thatch]], require a steep pitch in order to be waterproof and durable.<ref>[http://thatch.org/spec.htm Thatching specifications]</ref> 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. |
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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. |
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. |
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==Parts of a roof== |
==Parts of a roof== |
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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. |
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. |
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The roof structure is generally supported upon walls, although some building styles, for example, [[geodesic dome|geodesic]] and [[A-frame]], blur the distinction between wall and roof. |
The roof structure is generally supported upon walls, although some building styles, for example, [[geodesic dome|geodesic]] and [[A-frame]], blur the distinction between wall and roof. |
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===Support=== |
===Support=== |
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{{main|Roof construction}} |
{{main|Roof construction}} |
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[[Image:Linkopings stadsbibliotek roof2.jpg|thumb|The roof of a library, [[Sweden]].]] |
[[Image:Linkopings stadsbibliotek roof2.jpg|thumb|The roof of a library, [[Sweden]].]] |
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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 [[Japanese architecture|Oriental architecture]]. |
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 [[Japanese architecture|Oriental architecture]]. |
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Timber lends itself to a great variety of roof shapes. Moreover, because timber can be worked in a variety of ways, the timber structure can fulfil an aesthetic as well as practical function, when left exposed to view. |
Timber lends itself to a great variety of roof shapes. Moreover, because timber can be worked in a variety of ways, the timber structure can fulfil an aesthetic as well as practical function, when left exposed to view. |
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Stone [[Post and lintel|lintel]]s have been used to support roofs since [[Prehistory|prehistoric times]], but cannot bridge large distances. The stone arch came into extensive use in the [[Ancient Rome|Ancient Roman]] period and in variant forms could be used to span spaces up to 140 feet across. The stone arch or [[vault]], with or without ribs, dominated the roof structures of major architectural works for about 2,000 years, only giving way to iron beams with the [[Industrial Revolution]] and the designing of such buildings as [[Paxton]]'s [[The Crystal Palace|Crystal Palace]], completed 1851. |
Stone [[Post and lintel|lintel]]s have been used to support roofs since [[Prehistory|prehistoric times]], but cannot bridge large distances. The stone arch came into extensive use in the [[Ancient Rome|Ancient Roman]] period and in variant forms could be used to span spaces up to 140 feet across. The stone arch or [[vault]], with or without ribs, dominated the roof structures of major architectural works for about 2,000 years, only giving way to iron beams with the [[Industrial Revolution]] and the designing of such buildings as [[Paxton]]'s [[The Crystal Palace|Crystal Palace]], completed 1851. |
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With continual improvements in [[steel girder]]s, these became the major structural support for large roofs, and eventually for ordinary houses as well. Another form of [[girder]] is the [[reinforced concrete]] beam, in which metal rods are encased in concrete, giving it greater strength under [[tension]]. |
With continual improvements in [[steel girder]]s, these became the major structural support for large roofs, and eventually for ordinary houses as well. Another form of [[girder]] is the [[reinforced concrete]] beam, in which metal rods are encased in concrete, giving it greater strength under [[tension]]. |
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===Outer layer=== |
===Outer layer=== |
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[[Image:Njem house in Cameroon.jpg|thumb|[[Cameroon]], a wattle and daub house, roofed with banana leaves.]] |
[[Image:Njem house in Cameroon.jpg|thumb|[[Cameroon]], a wattle and daub house, roofed with banana leaves.]] |
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[[Image:Niigata NCM Peasant Rice Farmers House.jpg|thumb|[[Japan]], rice straw thatch]] |
[[Image:Niigata NCM Peasant Rice Farmers House.jpg|thumb|[[Japan]], rice straw thatch.]] |
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[[Image:The Elms Jersey.jpg|thumb|[[England]], slate]] |
[[Image:The Elms Jersey.jpg|thumb|[[England]], slate.]] |
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[[Image:Miskolc omassa peasant house.jpg|thumb|[[Hungary]], terracotta tiles]] |
[[Image:Miskolc omassa peasant house.jpg|thumb|[[Hungary]], terracotta tiles.]] |
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[[Image:Minenverwalter Kolmannskuppe.jpg|thumb|[[Namibia]], metal roof.]] |
[[Image:Minenverwalter Kolmannskuppe.jpg|thumb|[[Namibia]], metal roof.]] |
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This part of the roof shows great variation dependent upon availability of material. In simple [[vernacular architecture]], roofing material is often vegetation, such as thatches of different materials, the most durable being [[sea grass]] with a life of perhaps 40 years. In areas with an abundance of timber, wooden shingles are used, while in some countries the bark of certain trees can be peeled off in thick, heavy sheets and used for roofing. |
This part of the roof shows great variation dependent upon availability of material. In simple [[vernacular architecture]], roofing material is often vegetation, such as thatches of different materials, the most durable being [[sea grass]] with a life of perhaps 40 years. In areas with an abundance of timber, wooden shingles are used, while in some countries the bark of certain trees can be peeled off in thick, heavy sheets and used for roofing. |
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The 20th century saw the manufacture of composition 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. |
The 20th century saw the manufacture of composition 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. |
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[[Slate]] is an ideal, and durable material, while in the [[Swiss Alps]] roofs are made from huge slabs of stone, several inches thick. The slate roof is often considered the best type of roofing. A slate roof may last 75 to 150 years, and even longer. However, slate roofs are often expensive to install |
[[Slate]] is an ideal, and durable material, while in the [[Swiss Alps]] roofs are made from huge slabs of stone, several inches thick. The slate roof is often considered the best type of roofing. A slate roof may last 75 to 150 years, and even longer. However, slate roofs are often expensive to install – in the USA, for example, a slate roof may have the same cost as the rest of the house. Often, the first part of a slate roof to fail is the fixing nails; they corrode, allowing the slates to slip. In the UK, this condition is known as "nail sickness". Because of this problem, fixing nails made of [[stainless steel]] or [[copper]] are recommended, and even these must be protected from the weather. |
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Roofs made of cut turf (known as [[Green roofs]]) have good insulating properties and are increasingly encouraged as a way of "greening" the Earth. Adobe roofs are roofs of clay, mixed with binding material such as straw or animal hair, and plastered on lathes to form a flat or gently sloped roof, usually in areas of low rainfall. |
Roofs made of cut turf (known as [[Green roofs]]) have good insulating properties and are increasingly encouraged as a way of "greening" the Earth. Adobe roofs are roofs of clay, mixed with binding material such as straw or animal hair, and plastered on lathes to form a flat or gently sloped roof, usually in areas of low rainfall. |
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In areas where clay is plentiful, roofs of baked tiles have been the major form of roof. The casting and firing of roof tiles is an industry that is often associated with [[brickworks]]. While the shape and colour of tiles was once regionally distinctive, now tiles of many shapes and colours are produced commercially, to suit the taste of the purchaser. |
In areas where clay is plentiful, roofs of baked tiles have been the major form of roof. The casting and firing of roof tiles is an industry that is often associated with [[brickworks]]. While the shape and colour of tiles was once regionally distinctive, now tiles of many shapes and colours are produced commercially, to suit the taste of the purchaser. |
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Sheet metal in the form of [[copper]] and [[lead]] has also been used for many hundreds of years. Both are expensive but durable, the vast copper roof of [[Chartres Cathedral]], oxidised to a pale green colour, having been in place for hundreds of years. Lead, which is sometimes used for church roofs, was most commonly used as flashing in valleys and around chimneys on domestic roofs, particularly those of slate. Copper was used for the same purpose. |
Sheet metal in the form of [[copper]] and [[lead]] has also been used for many hundreds of years. Both are expensive but durable, the vast copper roof of [[Chartres Cathedral]], oxidised to a pale green colour, having been in place for hundreds of years. Lead, which is sometimes used for church roofs, was most commonly used as flashing in valleys and around chimneys on domestic roofs, particularly those of slate. Copper was used for the same purpose. |
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In the 19th century, iron, electroplated with [[zinc]] to improve its resistance to rust, became a light-weight, easily-transported, waterproofing material. While its insulating properties were poor, its low cost and easy application made it the most accessible commercial roofing, world wide. Since then, many types of metal roofing have been developed. Steel shingle or standing-seam roofs last about 50 years or more depending on both the method of installation and the moisture barrier (underlayment) used and are between the cost of shingle roofs and slate roofs. |
In the 19th century, iron, electroplated with [[zinc]] to improve its resistance to rust, became a light-weight, easily-transported, waterproofing material. While its insulating properties were poor, its low cost and easy application made it the most accessible commercial roofing, world wide. Since then, many types of metal roofing have been developed. Steel shingle or standing-seam roofs last about 50 years or more depending on both the method of installation and the moisture barrier (underlayment) used and are between the cost of shingle roofs and slate roofs. |
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In the 20th century a large number of roofing materials were developed, including roofs based on bitumen (already used in previous centuries), on rubber and on a range of synthetics such as [[thermoplastic]] and on [[fibreglass]]. |
In the 20th century a large number of roofing materials were developed, including roofs based on bitumen (already used in previous centuries), on rubber and on a range of synthetics such as [[thermoplastic]] and on [[fibreglass]]. |
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===Insulation=== |
===Insulation=== |
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[[Image:Snow on the roof.jpg|thumb|[[Snow]] on the roof of houses in [[Poland]].]] |
[[Image:Snow on the roof.jpg|thumb|[[Snow]] on the roof of houses in [[Poland]].]] |
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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 member of the roof. The purpose 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. |
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 member of the roof. The purpose 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. |
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Other 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. |
Other 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. |
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So called [[Cool roof]]s 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 [[emissivity]]. |
So called [[Cool roof]]s 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 [[emissivity]]. |
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===Drainage=== |
===Drainage=== |
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[[Image:Ashdod 2005, rooftop view p2.JPG|thumb|The flat roofs of the Middle East, [[Israel]].]] |
[[Image:Ashdod 2005, rooftop view p2.JPG|thumb|The flat roofs of the Middle East, [[Israel]].]] |
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[[Image:Jakriborg, juni 2005 x.jpg|thumb|The steeply pitched, gabled roofs of [[Scandinavia]].]] |
[[Image:Jakriborg, juni 2005 x.jpg|thumb|The steeply pitched, gabled roofs of [[Scandinavia]].]] |
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[[Image:Chinese-roof.jpg|thumb|thumb|The overhanging eaves of [[China]].]] |
[[Image:Chinese-roof.jpg|thumb|thumb|The overhanging eaves of [[China]].]] |
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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. |
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. |
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Flat roof of adobe dwellings generally have a very slight slope. In a Middle Eastern country, where the roof may be used for recreation, it is often walled, and drainage holes must be provided to stop water from pooling and seeping through the porous roofing material. |
Flat roof of adobe dwellings generally have a very slight slope. In a Middle Eastern country, where the roof may be used for recreation, it is often walled, and drainage holes must be provided to stop water from pooling and seeping through the porous roofing material. |
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Similar problems, although on a very much larger scale, confront the builders of modern commercial properties which often have flat roofs. Because of the very large nature of such roofs, it is essential that the outer skin is of a highly impermiable material. Most industrial and commercial structures have conventional roofs of low pitch. |
Similar problems, although on a very much larger scale, confront the builders of modern commercial properties which often have flat roofs. Because of the very large nature of such roofs, it is essential that the outer skin is of a highly impermiable material. Most industrial and commercial structures have conventional roofs of low pitch. |
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In general, the pitch of the roof is proportional to the amount of precipitation. Houses in areas of low rainfall frequently have roofs of low pitch while those in areas of high rainfall and snow, have steep roofs. The [[longhouse]]s of [[Papua New Guinea]], for example, being roof-dominated architecture, the high roofs sweeping almost to the ground. The high steeply-pitched roofs of Germany and Holland are typical in regions of snowfall. In parts of the North America such as [[Buffalo, New York|Buffalo]] USA or [[Montreal]] Canada, there is a required minimum slope of 6 inches in 12 inches, a pitch of 30 degrees. |
In general, the pitch of the roof is proportional to the amount of precipitation. Houses in areas of low rainfall frequently have roofs of low pitch while those in areas of high rainfall and snow, have steep roofs. The [[longhouse]]s of [[Papua New Guinea]], for example, being roof-dominated architecture, the high roofs sweeping almost to the ground. The high steeply-pitched roofs of Germany and Holland are typical in regions of snowfall. In parts of the North America such as [[Buffalo, New York|Buffalo]] USA or [[Montreal]] Canada, there is a required minimum slope of 6 inches in 12 inches, a pitch of 30 degrees. |
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There are regional building styles which contradict this trend, the stone roofs of the Alpine chalets being usually of gentler incline. These buildings tend to accumulate a large amount of snow on them, which is seen as a factor in their insulation. The pitch of the roof is in part determined by the roofing material available, a pitch of 3/12 or greater slope generally being covered with asphalt shingles, wood shake, corrugated steel, slate or tile. |
There are regional building styles which contradict this trend, the stone roofs of the Alpine chalets being usually of gentler incline. These buildings tend to accumulate a large amount of snow on them, which is seen as a factor in their insulation. The pitch of the roof is in part determined by the roofing material available, a pitch of 3/12 or greater slope generally being covered with asphalt shingles, wood shake, corrugated steel, slate or tile. |
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The water repelled by the roof during a rainstorm is potentially damaging to the building that the roof protects. If it runs down the walls, it may seep into the mortar or through panels. If it lies around the foundations it may cause seepage to the interior, [[rising damp (structural)|rising damp]] or [[dry rot]]. For this reason most buildings have a system in place to protect the walls of a building from most of the roof water. Overhanging [[eaves]] are commonly employed for this purpose. Most modern roofs and many old ones have systems of valleys, gutters, waterspouts, waterheads and [[drainpipe]]s to remove the water from the vicinity of the building. In many parts of the world, roofwater is collected and stored for domestic use. |
The water repelled by the roof during a rainstorm is potentially damaging to the building that the roof protects. If it runs down the walls, it may seep into the mortar or through panels. If it lies around the foundations it may cause seepage to the interior, [[rising damp (structural)|rising damp]] or [[dry rot]]. For this reason most buildings have a system in place to protect the walls of a building from most of the roof water. Overhanging [[eaves]] are commonly employed for this purpose. Most modern roofs and many old ones have systems of valleys, gutters, waterspouts, waterheads and [[drainpipe]]s to remove the water from the vicinity of the building. In many parts of the world, roofwater is collected and stored for domestic use. |
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Areas prone to heavy snow benefit from a steel roof because their smooth surfaces shed the weight of snow more easily and resist the force of wind better than a wood shingle or a concrete tile roof. |
Areas prone to heavy snow benefit from a steel roof because their smooth surfaces shed the weight of snow more easily and resist the force of wind better than a wood shingle or a concrete tile roof. |
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*mounted on a flat roof with a construction and additional weight to prevent uplift from wind. |
*mounted on a flat roof with a construction and additional weight to prevent uplift from wind. |
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==Roof shapes== |
==Roof shapes== |
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[[Image:Mandurah house.jpg|thumb|Flat roof, [[Western Australia]].]] |
[[Image:Mandurah house.jpg|thumb|Flat roof, [[Western Australia]].]] |
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[[Image:mount-gilead-ohio-jail.jpg|right|thumb|Mansard roof on a county jail, [[Mount Gilead, Ohio]].]] |
[[Image:mount-gilead-ohio-jail.jpg|right|thumb|Mansard roof on a county jail, [[Mount Gilead, Ohio]].]] |
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[[Image:RoundRoof.JPG|thumb|right|180px|A (half-)round roof]] |
[[Image:RoundRoof.JPG|thumb|right|180px|A (half-)round roof.]] |
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*[[flat roof| |
*[[flat roof|Flat]] |
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*[[ |
*[[Lean-to]] |
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*[[Skillion roof]] single-sloped, lean to, or shed roof |
*[[Skillion roof]] single-sloped, lean to, or shed roof |
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*(Asian traditional style) |
*(Asian traditional style) |
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*Ridged |
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*ridged |
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** |
**Pitched or [[gable]]d |
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*** |
***Shaped gable |
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***Dutch gable |
***Dutch gable – a hybrid of hipped and gable |
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***[[ |
***[[Crow-stepped gable]] (also called corbie step) gable |
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*** |
***Salt-box |
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** |
**Saddleback – a gabled roof atop a tower<ref>Fleming, Honour, & Pevsner, ''A Dictionary of Architecture''</ref> |
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**[[ |
**[[Hip roof]] includes a sketch of a Dutch gable (Australian terminology) |
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** |
**Half-hipped |
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**[[ |
**[[Mansard]] – with the pitch divided into a shallow slope above a steeper slope |
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**[[ |
**[[Gambrel]] – as a mansard, but on only two sides of the roof |
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** |
**Bell-cast – as a mansard, but with the shallow slope below the steeper slope |
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**[[Pavilion (structure)|pavilion]] |
**[[Pavilion (structure)|pavilion]] |
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*Conical |
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*conical |
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*Domical |
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*domical |
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*Catenary |
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*catenary |
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*Pyramidal |
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*pyramidal |
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*[[ |
*[[Saw-tooth]] |
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[[Image:Thai-roof.jpg|thumb|Temple roof Chang Mai, [[Thailand]] with a decorated gable end and ceramic tile covering.]] |
[[Image:Thai-roof.jpg|thumb|Temple roof Chang Mai, [[Thailand]] with a decorated gable end and ceramic tile covering.]] |
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[[Image:ReetdachHausKampenerHeideSylt.jpg|thumb|Reed thatch on the island of [[Sylt]].]] |
[[Image:ReetdachHausKampenerHeideSylt.jpg|thumb|Reed thatch on the island of [[Sylt]].]] |
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[[Image:roof.croyde.arp.750pix.jpg|thumb|A roof tiled in imitation of [[thatch]] at [[Croyde]], [[North Devon]], [[England]]]] |
[[Image:roof.croyde.arp.750pix.jpg|thumb|A roof tiled in imitation of [[thatch]] at [[Croyde]], [[North Devon]], [[England]].]] |
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[[Image:Chelmsko-slaskie-12apostolow.jpg|thumb|Wooden shingles.]] |
[[Image:Chelmsko-slaskie-12apostolow.jpg|thumb|Wooden shingles.]] |
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[[Image:DSCN3182 prospectnewtown e 600.jpg|thumb|[[USA]], bitumen]] |
[[Image:DSCN3182 prospectnewtown e 600.jpg|thumb|[[USA]], bitumen.]] |
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== Commercially available roofing materials== |
== Commercially available roofing materials== |
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The weather proofing material is the topmost or outermost layer, exposed to the weather. Many different kinds of materials have been used as weather proofing material: |
The weather proofing material is the topmost or outermost layer, exposed to the weather. Many different kinds of materials have been used as weather proofing material: |
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* [[Thatch]] is roofing made of plant material, in overlapping layers.<ref> |
* [[Thatch]] is roofing made of plant material, in overlapping layers.<ref>[http://thatch.org/ Thatching Information]</ref> |
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** Wheat [[Straw]], widely used in England, France and other parts of Europe. |
** Wheat [[Straw]], widely used in England, France and other parts of Europe. |
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**[[Seagrass]], used in coastal areas where there are [[estury|esturies]] such as Scotland. Has a longer life than straw. Claimed to have a life in exccess of 60 years.<ref>as claimed by |
**[[Seagrass]], used in coastal areas where there are [[estury|esturies]] such as Scotland. Has a longer life than straw. Claimed to have a life in exccess of 60 years.<ref>as claimed by [http://www.thatching.com/ McGhee & Co. Roof Thatchers].</ref> |
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* [[Roof shingle|Shingles]], called ''shakes'' in North America. ''Shingles'' is the generic term for a roofing material that is in many overlapping sections, regardless of the nature of the material. The word is also used specifically to denote shingles made of wood. |
* [[Roof shingle|Shingles]], called ''shakes'' in North America. ''Shingles'' is the generic term for a roofing material that is in many overlapping sections, regardless of the nature of the material. The word is also used specifically to denote shingles made of wood. |
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** [[Redcedar]]. Life expectancy, up to 30 years.<ref> |
** [[Redcedar]]. Life expectancy, up to 30 years.<ref>[http://72.14.253.104/search?q=cache:ks1Ak33enMsJ:www.pathnet.org/si.asp%3Fid%3D517+Wood+shingles&hl=en&ct=clnk&cd=5&gl=au Wood shakes and shingles]</ref> However, young growth redcedar has a short life expectancy. High cost. Should be allowed to breathe. <ref>[http://hometips.com/content/shingle_intro.html Hometips – Wooden shingle roofing, with good diagrams]</ref> |
||
** [[Hardwood]]. Very durable roofing found in Colonial [[Australian architecture]], its use now limited to [[restoration]]s. |
** [[Hardwood]]. Very durable roofing found in Colonial [[Australian architecture]], its use now limited to [[restoration]]s. |
||
** [[Slate]]. High cost with a life expectancy of up to 200 years.<ref> |
** [[Slate]]. High cost with a life expectancy of up to 200 years.<ref>[http://www.slateroofcentral.com/identify.html Slate Roof Central]</ref> Being a heavy material, the supporting structure must be very robust. |
||
** Ceramic [[tile]]. High cost, life of up to 100 years.<ref> |
** Ceramic [[tile]]. High cost, life of up to 100 years.<ref>[http://www.claytileroof.com/contracting_services/historic_renovation.asp Renaissance Roofing]</ref> |
||
*** [[Imbrex and tegula]], style dating back to ancient Greece and Rome. |
*** [[Imbrex and tegula]], style dating back to ancient Greece and Rome. |
||
** Metal shakes or shingles. Long life. High cost, suitable for roofs of 3/12 pitch or greater. Because of the flexibility of metal, they can be manufactured to lock together, giving durability and reducing assembly time.<ref> |
** Metal shakes or shingles. Long life. High cost, suitable for roofs of 3/12 pitch or greater. Because of the flexibility of metal, they can be manufactured to lock together, giving durability and reducing assembly time.<ref>[http://hometips.com/cs-protected/guides/metal_roofs/metalroof_shingles.html HomeTips: Metal shingle roofing]</ref> |
||
** Mechanically seamed metal. Long life. High cost, suitable for roofs of low pitch such as 0.5/12 to 3/12 pitch. |
** Mechanically seamed metal. Long life. High cost, suitable for roofs of low pitch such as 0.5/12 to 3/12 pitch. |
||
** [[Concrete]], usually reinforced with fibres of some sort. |
** [[Concrete]], usually reinforced with fibres of some sort. |
||
** [[Asphalt shingle]], made of bitumen embedded in an organic or fiberglass mat, usually covered with colored, man-made ceramic grit. Cheaper than slate or tiles. Various life span expectancies. |
** [[Asphalt shingle]], made of bitumen embedded in an organic or fiberglass mat, usually covered with colored, man-made ceramic grit. Cheaper than slate or tiles. Various life span expectancies. |
||
** [[Asbestos]] shingles. Very long lifespan, fireproof and low cost but now rarely used because of health concerns.<ref> |
** [[Asbestos]] shingles. Very long lifespan, fireproof and low cost but now rarely used because of health concerns.<ref>[http://www.betterhealth.vic.gov.au/BHCV2/bhcarticles.nsf/pages/Asbestos_and_your_health?open Asbestos and Your Health, Victorian Government]</ref><ref>[http://www.asbestosdiseases.org.au/asbestosinfo/asbestos_community.htm Asbestos Diseases Advisory Service]</ref> |
||
* Membrane. membrane roofing is in large sheets, generally fused in some way at the joints to form a continuous surface. |
* Membrane. membrane roofing is in large sheets, generally fused in some way at the joints to form a continuous surface. |
||
** [[Thermosetting plastic]] (e.g. [[EPDM rubber]]). Synthetic rubber sheets adhered together with contact adhesive or tape. Primary application is big box store with large open areas and little vertical protrusions. |
** [[Thermosetting plastic]] (e.g. [[EPDM rubber]]). Synthetic rubber sheets adhered together with contact adhesive or tape. Primary application is big box store with large open areas and little vertical protrusions. |
||
** [[Thermoplastic]] (e.g. [[polyvinyl chloride|PVC]], [[ThermoPlastic Olefin|TPO]], [[Hypalon|CSPE]]). Plastic sheets welded together with hot air creating one continuous sheet membrane. Can be rewelded with the exception of CSPE. Lends itself well to both big box and small roof application because of its hot air weldability. |
** [[Thermoplastic]] (e.g. [[polyvinyl chloride|PVC]], [[ThermoPlastic Olefin|TPO]], [[Hypalon|CSPE]]). Plastic sheets welded together with hot air creating one continuous sheet membrane. Can be rewelded with the exception of CSPE. Lends itself well to both big box and small roof application because of its hot air weldability. |
||
** Modified [[bitumen]] |
** Modified [[bitumen]] – heat welded, asphalt adhered or installed with adhesive. Asphalt is mixed with polymers such as APP or SBS, then applied to fiberglass and/or polyester mat, seams sealed by locally melting the asphalt with heat, hot mopping of asphalt, or adhesive. Lends itself well to all applications. |
||
** Built-Up Roof |
** Built-Up Roof – Multiple plies of asphalt saturated organic felt or coated fiberglass felts. Plies of felt are adhered with hot asphalt, coal tar pitch or adhesive. |
||
** Sprayed-in-Place Polyurethane Foam (SPUF) |
** Sprayed-in-Place Polyurethane Foam (SPUF) – Foam sprayed in-place on the roof, then coated with a wide variety of coatings, or in some instances, covered with gravel. |
||
** [[Textile|Fabric]] |
** [[Textile|Fabric]] |
||
*** [[ |
*** [[Polyester]]. |
||
*** [[PTFE]], (synthetic fluoropolymer) embedded in [[fibreglass]]. |
*** [[PTFE]], (synthetic fluoropolymer) embedded in [[fibreglass]]. |
||
[[Image:Custom-orb.jpg|thumb|250px|Corrugated iron sheeting a house under construction in Northern Australia. Shows two gables and external cyclonic fastenings.]] |
[[Image:Custom-orb.jpg|thumb|250px|Corrugated iron sheeting a house under construction in Northern Australia. Shows two gables and external cyclonic fastenings.]] |
||
* [[Metal roof]]ing. Generally a relatively inexpensive building material. |
* [[Metal roof]]ing. Generally a relatively inexpensive building material. |
||
** [[Galvanised steel]] frequently manufactured with wavy corrugations to resist lateral flexing and fitted with exposed fasteners. Widely used for low cost and durability. Sheds are normally roofed with this material. Known as ''Gal iron'' or ''Corro'', it was the most extensively used roofing material of 20th century Australia, now replaced in popularity by steel roofing coated with an alloy of zinc and aluminium, claimed to have up to four times the life of galvanized steel. <ref> |
** [[Galvanised steel]] frequently manufactured with wavy corrugations to resist lateral flexing and fitted with exposed fasteners. Widely used for low cost and durability. Sheds are normally roofed with this material. Known as ''Gal iron'' or ''Corro'', it was the most extensively used roofing material of 20th century Australia, now replaced in popularity by steel roofing coated with an alloy of zinc and aluminium, claimed to have up to four times the life of galvanized steel. <ref>[http://www.bluescopesteel.com.au/go/brands/zincalume-steel Bluescope]</ref> |
||
** Standing-seam metal with concealed fasteners. |
** Standing-seam metal with concealed fasteners. |
||
** Mechanically seamed metal with concealed fasteners contains sealant in seams for use on very low sloped roofs. |
** Mechanically seamed metal with concealed fasteners contains sealant in seams for use on very low sloped roofs. |
||
** Flat-seam metal with soldered seams. |
** Flat-seam metal with soldered seams. |
||
==Gallery of significant roofs== |
==Gallery of significant roofs== |
||
<gallery> |
<gallery> |
||
Image:Cupola santamariadelfiore.jpg|Imbrex and tegula tiles on the dome of [[Florence Cathedral]]. |
Image:Cupola santamariadelfiore.jpg|Imbrex and tegula tiles on the dome of [[Florence Cathedral]]. |
||
Image:B9a agra700.jpg|The marble dome of the [[Taj Mahal]]. |
Image:B9a agra700.jpg|The marble dome of the [[Taj Mahal]]. |
||
Image:Chenonceau 2006-06-24 15-30-31.JPG|The hip roofs and dormers of [[Chateau Chenonceau]]. |
Image:Chenonceau 2006-06-24 15-30-31.JPG|The hip roofs and dormers of [[Chateau Chenonceau]]. |
||
Image:Hospices de beaune toit.jpg|The polychrome tiles of the Hospice of Beaune, [[France]]. |
Image:Hospices de beaune toit.jpg|The polychrome tiles of the Hospice of Beaune, [[France]]. |
||
Image:Speyerer Dom Dach.jpg|The copper roof of [[Speyer Cathedral]], [[Germany]]. photo Wolfi. |
Image:Speyerer Dom Dach.jpg|The copper roof of [[Speyer Cathedral]], [[Germany]]. photo Wolfi. |
||
Image:Kings chapel roof.jpg|The lead roof of [[King's College Chapel]], [[England]]. |
Image:Kings chapel roof.jpg|The lead roof of [[King's College Chapel]], [[England]]. |
||
Image:Grand Palaais 501590 fh000033.jpg|The glass roof of the Grand Palais, [[Paris]]. |
Image:Grand Palaais 501590 fh000033.jpg|The glass roof of the Grand Palais, [[Paris]]. |
||
Image:SydneyOperaHouse6 gobeirne.jpg|The glazed ceramic tiles of the [[Sydney Opera House]]. |
Image:SydneyOperaHouse6 gobeirne.jpg|The glazed ceramic tiles of the [[Sydney Opera House]]. |
||
</gallery> |
</gallery> |
||
| Line 191: | Line 192: | ||
==References== |
==References== |
||
{{reflist|2}} |
|||
<references /> |
|||
==Further reading== |
==Further reading== |
||
* Francis Ching; ''Building Construction Illustrated'', ''Visual Dictionary of Architecture'', ''Architecture: |
* Francis Ching; ''Building Construction Illustrated'', ''Visual Dictionary of Architecture'', ''Architecture: Form, Space, and Order.'' |
||
==External links== |
==External links== |
||
Revision as of 08:45, 7 February 2009
A roof is the covering on the uppermost part of a building. A roof protects the building and its contents from the effects of weather. Structures that require roofs range from a letter box to a cathedral or stadium, dwellings being the most numerous.
In most countries a roof protects primarily against rain. Depending upon the nature of the building, the roof may also protect against heat, against sunlight, against cold and against wind. Other types of structure, for example, a garden conservatory, might use roofing that protects against cold, wind and rain but admits light. A verandah may be roofed with material that protects against sunlight but admits the other elements.
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.
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 lamininated glass, aluminium sheeting and precast concrete. In many parts of the world ceramic tiles have been the predominant roofing material for centuries.
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 domestic architecture, except in very dry regions, has roofs that are sloped, or pitched. The pitch is partly dependent upon stylistic factors, but has more to do with practicalities. Some types of roofing, for example thatch, require a steep pitch in order to be waterproof and durable.[1] 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.
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.
Parts of a roof
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
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.
Timber lends itself to a great variety of roof shapes. Moreover, because timber can be worked in a variety of ways, the timber structure can fulfil an aesthetic as well as practical function, when left exposed to view.
Stone lintels have been used to support roofs since prehistoric times, but cannot bridge large distances. The stone arch came into extensive use in the Ancient Roman period and in variant forms could be used to span spaces up to 140 feet across. The stone arch or vault, with or without ribs, dominated the roof structures of major architectural works for about 2,000 years, only giving way to iron beams with the Industrial Revolution and the designing of such buildings as Paxton's Crystal Palace, completed 1851.
With continual improvements in steel girders, these became the major structural support for large roofs, and eventually for ordinary houses as well. Another form of girder is the reinforced concrete beam, in which metal rods are encased in concrete, giving it greater strength under tension.
Outer layer
This part of the roof shows great variation dependent upon availability of material. In simple vernacular architecture, roofing material is often vegetation, such as thatches of different materials, the most durable being sea grass with a life of perhaps 40 years. In areas with an abundance of timber, wooden shingles 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 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.
Slate is an ideal, and durable material, while in the Swiss Alps roofs are made from huge slabs of stone, several inches thick. The slate roof is often considered the best type of roofing. A slate roof may last 75 to 150 years, and even longer. However, slate roofs are often expensive to install – in the USA, for example, a slate roof may have the same cost as the rest of the house. Often, the first part of a slate roof to fail is the fixing nails; they corrode, allowing the slates to slip. In the UK, this condition is known as "nail sickness". Because of this problem, fixing nails made of stainless steel or copper are recommended, and even these must be protected from the weather.
Roofs made of cut turf (known as Green roofs) have good insulating properties and are increasingly encouraged as a way of "greening" the Earth. Adobe roofs are roofs of clay, mixed with binding material such as straw or animal hair, and plastered on lathes to form a flat or gently sloped roof, usually in areas of low rainfall.
In areas where clay is plentiful, roofs of baked tiles have been the major form of roof. The casting and firing of roof tiles is an industry that is often associated with brickworks. While the shape and colour of tiles was once regionally distinctive, now tiles of many shapes and colours are produced commercially, to suit the taste of the purchaser.
Sheet metal in the form of copper and lead has also been used for many hundreds of years. Both are expensive but durable, the vast copper roof of Chartres Cathedral, oxidised to a pale green colour, having been in place for hundreds of years. Lead, which is sometimes used for church roofs, was most commonly used as flashing in valleys and around chimneys on domestic roofs, particularly those of slate. Copper was used for the same purpose.
In the 19th century, iron, electroplated with zinc to improve its resistance to rust, became a light-weight, easily-transported, waterproofing material. While its insulating properties were poor, its low cost and easy application made it the most accessible commercial roofing, world wide. Since then, many types of metal roofing have been developed. Steel shingle or standing-seam roofs last about 50 years or more depending on both the method of installation and the moisture barrier (underlayment) used and are between the cost of shingle roofs and slate roofs. In the 20th century a large number of roofing materials were developed, including roofs based on bitumen (already used in previous centuries), on rubber and on a range of synthetics such as thermoplastic and on fibreglass.
Insulation
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 member of the roof. The purpose 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.
Other 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 emissivity.
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.
Flat roof of adobe dwellings generally have a very slight slope. In a Middle Eastern country, where the roof may be used for recreation, it is often walled, and drainage holes must be provided to stop water from pooling and seeping through the porous roofing material.
Similar problems, although on a very much larger scale, confront the builders of modern commercial properties which often have flat roofs. Because of the very large nature of such roofs, it is essential that the outer skin is of a highly impermiable material. Most industrial and commercial structures have conventional roofs of low pitch.
In general, the pitch of the roof is proportional to the amount of precipitation. Houses in areas of low rainfall frequently have roofs of low pitch while those in areas of high rainfall and snow, have steep roofs. The longhouses of Papua New Guinea, for example, being roof-dominated architecture, the high roofs sweeping almost to the ground. The high steeply-pitched roofs of Germany and Holland are typical in regions of snowfall. In parts of the North America such as Buffalo USA or Montreal Canada, there is a required minimum slope of 6 inches in 12 inches, a pitch of 30 degrees.
There are regional building styles which contradict this trend, the stone roofs of the Alpine chalets being usually of gentler incline. These buildings tend to accumulate a large amount of snow on them, which is seen as a factor in their insulation. The pitch of the roof is in part determined by the roofing material available, a pitch of 3/12 or greater slope generally being covered with asphalt shingles, wood shake, corrugated steel, slate or tile.
The water repelled by the roof during a rainstorm is potentially damaging to the building that the roof protects. If it runs down the walls, it may seep into the mortar or through panels. If it lies around the foundations it may cause seepage to the interior, rising damp or dry rot. For this reason most buildings have a system in place to protect the walls of a building from most of the roof water. Overhanging eaves are commonly employed for this purpose. Most modern roofs and many old ones have systems of valleys, gutters, waterspouts, waterheads and drainpipes to remove the water from the vicinity of the building. In many parts of the world, roofwater is collected and stored for domestic use.
Areas prone to heavy snow benefit from a steel roof because their smooth surfaces shed the weight of snow more easily and resist the force of wind better than a wood shingle or a concrete tile roof.
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.
There are different ways that solar systems can be integrated with roofs:
- integrated in the covering of pitched roofs, e.g. solar shingles.
- mounted on an existing roof, e.g. solar panel on a tile roof.
- integrated in a flat roof membrane using heat welding, e.g. PVC.
- mounted on a flat roof with a construction and additional weight to prevent uplift from wind.
Roof shapes
- Flat
- Lean-to
- Skillion roof single-sloped, lean to, or shed roof
- (Asian traditional style)
- Ridged
- Pitched or gabled
- Shaped gable
- Dutch gable – a hybrid of hipped and gable
- Crow-stepped gable (also called corbie step) gable
- Salt-box
- Saddleback – a gabled roof atop a tower[2]
- Hip roof includes a sketch of a Dutch gable (Australian terminology)
- Half-hipped
- Mansard – with the pitch divided into a shallow slope above a steeper slope
- Gambrel – as a mansard, but on only two sides of the roof
- Bell-cast – as a mansard, but with the shallow slope below the steeper slope
- pavilion
- Pitched or gabled
- Conical
- Domical
- Catenary
- Pyramidal
- Saw-tooth
Commercially available roofing materials
The weather proofing material is the topmost or outermost layer, exposed to the weather. Many different kinds of materials have been used as weather proofing material:
- Thatch is roofing made of plant material, in overlapping layers.[3]
- Shingles, called shakes in North America. Shingles is the generic term for a roofing material that is in many overlapping sections, regardless of the nature of the material. The word is also used specifically to denote shingles made of wood.
- Redcedar. Life expectancy, up to 30 years.[5] However, young growth redcedar has a short life expectancy. High cost. Should be allowed to breathe. [6]
- Hardwood. Very durable roofing found in Colonial Australian architecture, its use now limited to restorations.
- Slate. High cost with a life expectancy of up to 200 years.[7] Being a heavy material, the supporting structure must be very robust.
- Ceramic tile. High cost, life of up to 100 years.[8]
- Imbrex and tegula, style dating back to ancient Greece and Rome.
- Metal shakes or shingles. Long life. High cost, suitable for roofs of 3/12 pitch or greater. Because of the flexibility of metal, they can be manufactured to lock together, giving durability and reducing assembly time.[9]
- Mechanically seamed metal. Long life. High cost, suitable for roofs of low pitch such as 0.5/12 to 3/12 pitch.
- Concrete, usually reinforced with fibres of some sort.
- Asphalt shingle, made of bitumen embedded in an organic or fiberglass mat, usually covered with colored, man-made ceramic grit. Cheaper than slate or tiles. Various life span expectancies.
- Asbestos shingles. Very long lifespan, fireproof and low cost but now rarely used because of health concerns.[10][11]
- Membrane. membrane roofing is in large sheets, generally fused in some way at the joints to form a continuous surface.
- Thermosetting plastic (e.g. EPDM rubber). Synthetic rubber sheets adhered together with contact adhesive or tape. Primary application is big box store with large open areas and little vertical protrusions.
- Thermoplastic (e.g. PVC, TPO, CSPE). Plastic sheets welded together with hot air creating one continuous sheet membrane. Can be rewelded with the exception of CSPE. Lends itself well to both big box and small roof application because of its hot air weldability.
- Modified bitumen – heat welded, asphalt adhered or installed with adhesive. Asphalt is mixed with polymers such as APP or SBS, then applied to fiberglass and/or polyester mat, seams sealed by locally melting the asphalt with heat, hot mopping of asphalt, or adhesive. Lends itself well to all applications.
- Built-Up Roof – Multiple plies of asphalt saturated organic felt or coated fiberglass felts. Plies of felt are adhered with hot asphalt, coal tar pitch or adhesive.
- Sprayed-in-Place Polyurethane Foam (SPUF) – Foam sprayed in-place on the roof, then coated with a wide variety of coatings, or in some instances, covered with gravel.
- Fabric
- Polyester.
- PTFE, (synthetic fluoropolymer) embedded in fibreglass.
- Metal roofing. Generally a relatively inexpensive building material.
- Galvanised steel frequently manufactured with wavy corrugations to resist lateral flexing and fitted with exposed fasteners. Widely used for low cost and durability. Sheds are normally roofed with this material. Known as Gal iron or Corro, it was the most extensively used roofing material of 20th century Australia, now replaced in popularity by steel roofing coated with an alloy of zinc and aluminium, claimed to have up to four times the life of galvanized steel. [12]
- Standing-seam metal with concealed fasteners.
- Mechanically seamed metal with concealed fasteners contains sealant in seams for use on very low sloped roofs.
- Flat-seam metal with soldered seams.
Gallery of significant roofs
-
Imbrex and tegula tiles on the dome of Florence Cathedral. -
The marble dome of the Taj Mahal.
-
The hip roofs and dormers of Chateau Chenonceau. -
The polychrome tiles of the Hospice of Beaune, France. -
The copper roof of Speyer Cathedral, Germany. photo Wolfi. -
The lead roof of King's College Chapel, England. -
The glass roof of the Grand Palais, Paris. -
The glazed ceramic tiles of the Sydney Opera House.
See also
Wikimedia Commons has media related to Roofs.
- Bituminous waterproofing
- Building construction
- Building envelope
- Green roof
- Metal roof
- Metal Roofing Alliance
- Roof garden
- Roofer
- Roofing felt
- Solar panel
- Tensile architecture
- Tented roof
- Thin-shell structure
- Tile
History
References
- ^ Thatching specifications
- ^ Fleming, Honour, & Pevsner, A Dictionary of Architecture
- ^ Thatching Information
- ^ as claimed by McGhee & Co. Roof Thatchers.
- ^ Wood shakes and shingles
- ^ Hometips – Wooden shingle roofing, with good diagrams
- ^ Slate Roof Central
- ^ Renaissance Roofing
- ^ HomeTips: Metal shingle roofing
- ^ Asbestos and Your Health, Victorian Government
- ^ Asbestos Diseases Advisory Service
- ^ Bluescope
Further reading
- Francis Ching; Building Construction Illustrated, Visual Dictionary of Architecture, Architecture: Form, Space, and Order.
External links
