Category Archives: LETTER R

Roof – the Top Covering of a Building

Part of the building that limits it from the top and protects it against atmospheric conditions. It directly protects the ceilings or vaults of the highest storey, or is a direct covering of the interior. Thanks to its artistic values, such as the spatial value and colour, it largely shapes the entire body of the building.

The roof consists of a load-bearing structure and a covering (sheathing, roofing). The supporting structure in steep roofs consists of wooden carpentry trusses, i.e. a timber roof truss, steel and prefabricated, reinforced concrete trusses. In slightly sloping and horizontal roofs, the supporting structure consists of beams, trusses and plates. In the roofs with curved surfaces, the supporting structure was formerly a timber roof truss, and now reinforced concrete shells. Roofing is covered with tiles, shingles, slate, sheet metal, tar paper, straw, reed etc.

The upper surfaces of the roofing are called roof slopes, and the place of intersection of slopes – corners when they form an acute angle. On the other hand, when an obtuse angle is created, the places of intersection of the slopes are called roof valleys. The vertical plane limiting the roof slopes to the side is called the gable. The lower edge of the slope protruding beyond the face of the wall is called the eaves, and the upper edge, which is the line of intersection of the two slopes, parallel to the eaves, is called the ridge (peak, gable line).

Conical roof, Nanhai Academy in Taipei. National Taiwan Science Education Center Chinese style roof at the Nanhai Academy, Taipei City. Photo by Meiguoren~commonswiki (2011). CC0. Colours intensified. Photo source: “Roof” (2021). In: Wikipedia. The Free Encyclopedia.

The eaves can rest on corbels, the ends of the beams, etc. Under the eaves, horizontal gutters and special funnels connected with vertical gutters to the sewage network are attached to drain the rainwater.

The attic is the space between the highest ceiling or vault of the building and the covering, filling the zone of the roof truss. The attic can be extended for residential purposes. The slope of the roof slopes depends on the climatic conditions and the type of covering.

Depending on the angle of inclination (slope) and shape, it is possible to distinguish the following roofs:

Flat (terraced-type) roofs, usually devoid of roof truss.

Sloped roofs (high, steep) with a clear slope. The sloping roof can be single-slope roof (mono-pitched, pent), gable roof (two-slope, saddleback) or multi-pitched (multi-slope).

The variants of gable and hipped roofs are: a half-hipped roof, which has got a gable with pediments, that is to say, small triangular slopes cutting the gables from the top. By these means, the gable is replaced here at the top and bottom of the roof by roof slopes, as in the case of the Black Forest house (German: Schwarzwaldhaus). There is also a gablet roof or dutch gable roof, hipped with half-gables or abutments. “A hybrid of hipped and gable with the gable (wall) at the top and hipped lower down. […] Overhanging eaves forming shelter around the building are a consequence where the gable wall is in line with the other walls of the buildings; i.e., unless the upper gable is recessed” (“List of roof shapes” 2021). Its variety is the roof of Podhale (in southern Poland).

House of a Black Forest peasant farmer around 1900. Unknown author – This image is available from the United States Library of Congress’s Prints and Photographs division under the digital ID ppmsca.00288. Public domain. Colours intensified. Photo source: “Black Forest house” (2020). In: Wikipedia. The Free Encyclopedia.

Curved roofs with curved or warped surfaces. A special variation is the flat roof with concave slopes, reducing its slope downwards.

Helm is a steep tower roof in the form of a pyramid, cone, also with curved slopes, or in the shape of a dome.

Onion roof resembles an onion and is especially found in southern Germany, Austria and Russia.

Bulbous cupola had originated from the onion roof, but it is concave in the lower part; often it is the basis of a multi-storey helmet. In the Baroque style, the roof is topped with a lantern.

Gabled steeple is a multi-slope roof, in a quadrilateral or polygonal projection,resembling the form of an accordion.

Rhomboidal roof consists of a diamond-shaped slopes.

Transverse roofs covering a church are distinguished by the coverage of the side aisles with a row of gable roofs parallel to each other, transverse to the longitudinal axis of the church.

Raised roofs are typical of the type B of the so called stave churches in Norway (see Hopperstad Stavekirke: Under the Surveillance of Wooden Dragons). “On the stone foundation, four huge ground beams (…) are placed. (…) The ends of these beams support the sills of the outer walls, forming a separate horizontal frame. The tall internal posts are placed on the internal frame of ground beams, and carry the main roof above the central nave (…). On the outer frame of sills rest the main wall planks (…), carrying the roof over the pentice or aisles (…) surrounding the central space” (“Stave church” 2021). The two roofs are made of roof shingles and, by the way of being constructed, they slope down in two steps, as in a basilica, giving a beautiful effect of a single overhung, usually multi-tiered and cascading roof.

Tiered roof, a type having a series of overlapping rows or levels placed one above the other. It occurs, for instance, in raised roofs of stave churches (Norway) or in prasats (Thai architecture).

Clerestory roofs, typical of a basilica type of churches and cathedrals. A clerestory covers a high section of the church, which wall contains windows above eye level. Its purpose is to admit light into the main nave of the church, situated between two lower and separately roofed aisles.

Shell roof (contemporary times) covers a spherical structure supported on its four corners.

Suspended roof (contemporary times) the weight of which rests on oval supports and allows large areas to be covered without internal supports.

A curved roof, including a tower roof (cupola), a spire, a conical roof, a spherical, domed (cupola), and an onion-shaped roof always have one gable point. A decorative round or polygonal canopy, placed on a tower or a spire in those types of roofs is called a cap.

Mansard roofs are roofs with two storeys of slopes separated from each other by a break, a step, a cornice or a wall. The roof was named after the French architect J. H. Mansart (1648-1708), whose design makes it possible to place residential rooms with sloping walls (mansards) in the attic. This type of roof also includes the Polish mansard roof, and its variant, the roof of Cracow (Poland).

Type of the roof of Cracow, applied in a design of an outbuilding of the Ustronie castle in Warsaw (architect S. Zawadzki). Drawing from C. Antonini – Książka Ireny Malinowskiej – “Stanisław Zawadzki” (1953). Public domain. Photo source: “Dach krakowski” (2020). In: Wikipedia. Wolna encyklopedia.

Shed roofs consist of several asymmetrical gable roofs arranged one after the other in such a way that the cross-section of the roof creates a toothed line. Usually, less steep roofs form a cover in a saw-tooth roof, while windows are placed in steeper slopes, which allows good lighting of workshop rooms.

Tented or pavilion roofs (hipped; in the form of a pyramid) have several triangular slopes, depending on the projection of the covered building (quadrangular, rectangular, polygonal), descending overhead at one gable point. For example, in a square projection, the four roof slopes meet at one gable point.

Pitched roofs (concave, recessed) have slopes with a slope towards the center of the building, forming a trough or a basin, with adequate water drainage, often covered with an attic. In contemporary architecture, there is a return to curved roofing, based on new construction solutions.

Surfaces and solids of the roof can be enriched with a decorative roofing system, openings, mansards, dormers, skylights, chimneys, and with special decorations: pinnacles, combs, laces and balustrades.

Featured image: Zakopane (Poland), a house with a half-gable roof. The roof is characteristic of the architecture of Podhale, hence it is also called the Zakopane or Podhale roof. Photo by Januszk57 (2012). CC BY-SA 3.0 pl. Photo source: “Dach półszczytowy” (2021). Wikipedia. Wolna encyklopedia.

BIBLIOGRAPHY:

“Dach półszczytowy” (2021). In: Wikipedia. Wolna encyklopedia. Available at <https://bit.ly/3tgL7MF>. [Accessed 1st February, 2021].

“Black Forest house” (2020). In: Wikipedia. The Free Encyclopedia. Available at <https://bit.ly/2NXEqyX>. [Accessed 1st February, 2021].

“Dach krakowski” (2020). In: Wikipedia. Wolna encyklopedia. Available at <https://bit.ly/3tpk7L9>. [Accessed 1st February, 2021].

“Dach pilasty” (2021). In: Wikipedia. Wolna encyklopedia. Available at <https://bit.ly/3ahe5mI>. [Accessed 1st February, 2021].

“List of roof shapes” (2021). In: Wikipedia. The Free Encyclopedia. Available at <https://bit.ly/3tiNWgg>. [Accessed 1st February, 2021].

“Roof” (2021). In: Wikipedia. The Free Encyclopedia. Available at <https://bit.ly/36x2LSn>. [Accessed 2nd February, 2021].

“Stave church” (2021). In: Wikipedia. The Free Encyclopedia. Available at <https://bit.ly/3reLRQr>. [Accessed 1st February, 2021].

Koch W. (2009) Style w architekturze. Arcydzieła budownictwa europejskiego od antyku po czasy współczesne. [Baustilkunde], pp. 244, 281, 436, 680. Baraniewski W., Kunkel R., Omilanowska M., Sito J., Zięba A., Żak K. trans. Warszawa: Świat Książki.

PWN (2007). Słownik terminologiczny sztuk pięknych, pp. 81-82. Kubalska-Sulkiewicz K., Bielska-Łach M., Manteuffel-Szarota A. eds. Wydanie piąte. Warszawa: Wydawnictwo Naukowe PWN.