In the building industry, a roof is a construction that closes the rooms and surfaces underneath at the top and thus protects them from the sun, weather or other influences that penetrate from above. The roof can be an independent roof structure over open spaces (e.g. flight roof ), but it is usually the top end of a building . In this case, together with the outer walls, it separates the outside space from the inside space and protects against the weather. Its design is characteristic of the entire building and depends on climatic conditions, building materials and building styles. A wide variety of roof shapes have developed over the course of architectural history .
The surfaces of the roof visible from the outside - whether inclined or flat, flat or curved - are the roof surfaces , their boundary and common intersection lines are the roof edges . The upper horizontal cutting edge of two roof surfaces is called the ridge . The lower horizontal edge of the roof surface is called the eaves . Usually the gutter is attached here.
The gable is the upper final wall surface of a building in the area of the roof. The roof edge on the gable is called the verge or place . This connects eaves and ridge and limits the gable at the top. Edges where two roof surfaces meet in the slope are called ridge (outer edge) or valley (inner edge). A point at which three or more roof surfaces meet is called the point of attack .
A roof always tries to follow simple geometric shapes, generally rectangles. Roof design is called the transfer of the roof into the floor plan . Sits a roof of a composite of a plurality of geometric shapes in plan view, one speaks of an assembled roof , roof with recurrence , decomposing roof or Dachzerfallung . Skewed polygons are referred to as a crooked roof - here the roof surfaces are inevitably curved.
Interruptions or penetrations in the roof skin are referred to as roof openings , for example skylights or dormers, but also the passages of the chimneys (chimneys). The attic is an upper floor in the attic, the attic is an undeveloped room in the same area (in some constructions, no differentiation is made). Roof decorations are all decorative elements attached to the roof.
Dimensions of the roof
The term ridge height refers to the distance from the upper edge of the cultivable road traffic area to the upper edge of the roof skin of the ridge. The eaves height is the distance from the upper edge of the cultivable road traffic area to the (theoretical) cut edge of the outer wall and the upper edge of the roof covering. The roof height is the vertical dimension from the eaves edge to the ridge, the basic horizontal dimension . The roof overhang is the horizontal distance between the eaves edge and the outer edge of the outer wall. The roof pitch describes the slope (steepness) of a roof surface. It is usually given as an angle in degrees , sometimes also in percent .
In general, the roof pitch is constant over the entire roof - or in the case of composite roofs of a roof section. Depending on the roof pitch, one differentiates:
- Flat roof : 0 ° –10 ° (German building regulations ); 0 ° –5 ° (Austria)
- Inclined roof:> 10 ° (German building regulations); > 7 ° ( DIN 1055 ); > 5 ° (Austria)
- Flat pitched roof: 10 ° –22 °, occasionally up to 30 ° roof pitch
- Pitched roof: over 22 ° or 30 ° roof pitch; Occasionally the term steep roof is used synonymously with sloping roof . Then one speaks of a pitched roof from 7 ° .
Historical development of the roof
The historical development of the roof goes back a long way. Around 12,000 BC Chr. Hunters and gatherers began to build pent roof-like structures from poles and round wood. The roof consisted of grass, heather or fur. A few millennia later, people built dwellings in sunk pits with gable roofs . In the course of time, dwellings with vertical walls developed and the pits became less and less important. Saddle roofs and hip roofs served to protect these houses. The regional differences in the roof shapes, and thus in the architecture, were always determined by the amount of wood. From the 13th to the 16th century there was a rapid development in construction and building technology. At the beginning of the 13th century, stone houses were still the exception, but in the later course the stone buildings became more and more important. The rafter roof , which was structurally cumbersome up to that time , was replaced by the purlin roof in the 17th century and the mansard roof was added a hundred years later . A short time later and throughout the 19th century, a variety of roof shapes developed. Initially, the dominant steep roof , and later won shallow pitched roofs and the flat roof in importance.
Roof construction describes the supporting structure of a roof, the construction necessary for its stability . The term is differentiated from roofing and roof cladding insofar as these are supported by the roof structure. A comparable term is roof structure , as the structure of a roof. Roof work means the combination of wooden roof structure. Roof scaffolding is another alternative name for the entirety of the structure supporting the roof membrane.
The building material wood plays an important role in roof structures , especially in the two classic variants, the rafter roof and the purlin roof . The second traditionally important natural building material in carpentry is bamboo , which has produced independent forms of roof structures in East Asia.
Since the 19th century are increasingly Steel -structures use, in addition since the 20th century structures made of steel and reinforced concrete , and tent constructions . All these newer constructions can be found in particular on wide-span roofs over train stations , hangars , grandstands , as well as other large halls and flight roofs. In contemporary architecture , plastics and composite materials are increasingly being used for construction.
As a roof structure is referred to the building construction assembly of a roof, that is the combination of layering and supporting and sealing components. One differentiates:
- Single-skin roofs (previously: warm roofs , today: non-ventilated roofs)
- Inverted roofs
- Double-skin roofs (formerly: cold roofs , today: ventilated roofs)
The roof skin is the outer layer of the roof, i.e. the roof covering on sloping roofs (rainproof, but not waterproof) or the roof waterproofing (impermeable to water) on flat roofs. A covered roof only protects against rain, a sealed roof is waterproof. However, the boundary between roofing and waterproofing is fluid. Different materials are used depending on the design, inclination, weather and legal conditions. A distinction is made between hard and soft roofing , whereby the fire behavior is decisive.
Roofs can be classified according to their roof shape , among other things . However, many roofs are combinations of different constructions, shapes or mixed forms, as well as roofs composed of several forms.
In general, human settlement history distinguishes between two basic roof forms: the flat roof and the sloping pitched roof. Flat roofs are particularly found in dry, warm residential areas, whereas the sloping roof is found in areas of the world that are exposed to damp and changing weather conditions. Originally, the flat roof was not used solely for weather protection, but also served as a lounge area, water collection point, shade or viewing platform ( pueblo design in North America). The pitched roof, on the other hand, initially served as a sloping level with which rainwater could easily be drained away, and later as additional protection against fire (hard roofing). This roof shape can be found above all in the cultural regions in the north and south of Europe and Asia ( China , Japan ), which are subject to intensive climatic conditions . Through colonization , the conquerors, especially from old Europe, carried this roof shape with them to the “New World” of South America or to the areas they had subjugated. There it was carried out mainly on church and sacred buildings.
Flat roof - flat or only slightly (up to 10 degrees) inclined roof surface
- Platform roof, a level flat roof without a roof pitch (in contrast to flat roofs with a low pitch angle)
- Sloped roof
- Berlin roof , asymmetrical roof shape with a steep roof half on the front side
- Arched roof , slightly arched roof (flatter than the barrel roof)
- Folding roof , similar to the rhombic roof, but with diamonds “folded” inwards
- Bell roof , above convex and below concave helmet
- Trench roof , stringing together of butterfly roofs
- Half-barrel roof, roof in the form of a horizontal quarter cylinder, similar to the monopitch roof with a higher wall on the ridge side
- Conical roof , conical roof
- Glued roof , "glued" to the facade to protect the windows from the weather
- Half- hip roof , hip roof with a reduced hip
- Dome roof , roof in the form of a dome
- Lantern roof, made up of two oppositely inclined roof surfaces that meet at the roof ridge
- Mansard roof , roof shape with steep roof surfaces in the lower area and flat roof areas in the upper area
- Parallel roof or hollow roof, row of gable roofs
- Monopitch roof , single sloping roof surface
- Pyramid roof , tent roof over a square floor plan
- Rhomb roof or diamond roof, usually consists of four lozenges and four gables over a square floor plan
- Ring pent roof , monopitch roof over a circular floor plan (usually part of a tower roof)
- Saddle roof , classic roof shape made up of two inclined roof surfaces that meet in the ridge
- Sliding roof , extension of a roof area beyond the eaves, similar to the pent roof
- Butterfly roof, two roof surfaces with a common interior eaves and two ridges on the outside (reverse principle of the gable roof)
- Shed roof , sawtooth-shaped rows of two differently steep roof surfaces (often on factory halls)
- Barrel roof , roof in the form of a lying half-cylinder
- Hipped roof , roof with four roof surfaces, instead of a gable, the narrow sides are also bevelled
- Tent roof , several roof surfaces inclined towards one another
- Zollinger roof , an intermediate form of mansard roof and barrel roof
- Onion dome , above concave, convex below Helm
- Trimmed roof: A trimmed roof is a sloping roof that is cut off horizontally under the ridge so that a flat roof is not a loft .
- Free-form roof: shells, domes, other geometric shapes, completely free forms of modern architecture
Roof structures and roof incisions
The attic can be used as storage, utility or living space. To make the roof area usable for these purposes, there are different types of roof structures, openings and incisions:
- Roof balcony : like roof loggia , but protrudes partially like a balcony from the structure
- Roof window : slanting windows in the roof area, for lighting and ventilation of the roof space
- Dormer : Structure for enlarging and illuminating the living space under the roof, set back from the facade
- Roof lantern : roof structure on the gable with windows to illuminate the interior
- Roof turret : a (often wooden) slim turrets on the roof ridge
- Loggia (also: roof loggia or negative dormer): an incision in the roof for an open, accessible platform which, unlike a balcony, does not protrude from the front of the house, but lies within the building.
- Zwerchhaus : roof section pushed open transversely, gable placed on the facade
Technical installations in the roof area
Because the roof is usually the top part of a building, the roof area is used for various technical installations that require a high position. There are also systems for maintaining and securing the roof area.
- Access aids for roof maintenance (steps)
- Lightning protection system
- Roof antenna , satellite dish
- Equipment for roof drainage such as gutter , downpipe or water spouts
- Devices against roof avalanches , so-called snow guard systems , for example snow guard grids, snow guard hooks or snow guard bars
- Chimneys and ventilation pipes
- Solar system , solar collector
- Photovoltaic system
If it is necessary that a fire wall protrudes over the roof surface, this divides the roof surface in a clearly visible manner. This is always the case when using soft roofing. Here the fire wall must always be at least 50 cm above the roof surface. In residential buildings with hard roofs and more than 3 full storeys, fire walls must be at least 30 cm above the roof area. In buildings with up to three full storeys without an increased risk of fire and when using hard roofs, the fire wall constructions can also be designed so that they do not appear in the roof area. Even if the roof surfaces are made with roofing felt or a similar roof membrane, a clear division can be seen even if the fire wall is routed under the roof, because the roofing felt must be replaced by sheet metal or other non-combustible building materials in the area of the fire wall .
- Bring everything under one roof : everything was successfully completed. One interpretation of the idiom derives this from the fact that a house (construction) was considered finished earlier when the roof and the compartments were finished. Lutz Röhrich derives this in his lexicon of proverbial idioms from the recovery of the harvest in the rural storage rooms.
- to step on someone's roof : comes from the early Germanic period and means something like 'to rebuke someone' and 'to publicly expose'. It is derived from the old custom of covering a man's roof when he has broken the law. Order is understood to mean both the legal system and the moral social rules. In particular, the roof was covered for those who had lost control of the household to their wife or who had been defeated by her. The custom was mainly carried out by the neighbors who wanted to expose the man with it. The roof is synonymous with house, protection and security. The discredited man had to straighten the roof on his own.
- The attic is equated with the mind that has its seat at the top of the head . Correspondingly, roof damage is assumed if one thinks that someone is “not quite right” in their head.
- to put the red rooster on someone's roof : means 'set a person on fire'. The 'red rooster' is to be equated with the word 'fire' or 'fire'. Going back to the Middle Ages, the rooster was the symbol of the fire god, as its striking, red plumage was reminiscent of wild fire. So if you already had a red rooster on the roof, you thought you were safe from fires.
- G. Binding, H. Hinz, J.-P. Sosson, K. Bedal, E. Polla, JT Smith, H. Hellenkemper, Ch. Ewert: Dach . In: Lexicon of the Middle Ages (LexMA). Volume 3, Artemis & Winkler, Munich / Zurich 1986, ISBN 3-7608-8903-4 , Sp. 409-426.
- Dierks, Schneider, Wormuth: Building construction . Werner-Verlag, ISBN 3-8041-1374-5 .
- Hermann Hederich: Elements of roof shapes, or presentation and averaging of the various types of roofing bodies, with allusion to their formation and decomposition, along with suggestion for calculating the same . Weimar 1858, text: digitized , plates: digitized
- Wolfgang Lauter : Roofs and gables . (= The bibliophile paperbacks; No. 454). Harenberg, Dortmund 1985, ISBN 3-88379-454-6 (illustrated book with an afterword by Kyra Stromberg ).
- Erwin Marx, Hugo Koch, Ludwig Schwering: Digitized roof coverings . (= Handbook of Architecture; Part 3: Die Hochbau-Bauen; Vol. 2, Raumbegrenzende Bauen; Book 5). Bergstrasse (Kröner), Stuttgart 1899.
- Friedhelm Maßong: Roof Tables. Calculations and work aids . 3rd edition, R. Müller, Cologne 2011, ISBN 978-3-481-02493-2 .
- Eberhard Schunck , Heide Wessely (Red.): Roof Atlas. Pitched roofs . 4th edition, Institute for International Architecture Documentation, Munich 2002.