The blanket is the hat of the house. It ensures the waterproofing of the roof, thanks to different materials placed on the frame. Tiles, slates, shingles, corrugated sheets ensure the protection of the interior of the house.
The work of the roofer begins with the realization of the supports on which he lays the roofing materials. These "supports" are themselves based on a frame composed of prefabricated elements or made to measure. Usually made of wood, the frame can also be metallic. A cover also includes galvanizing elements, gutters to evacuate the runoff water. It is often equipped with roof windows.
It is a network of pieces of wood (the battens) of small section (27 x 40 mm, for example), related to the cover material to be supported, oak, conifer or chestnut, which are nailed on rafters or farmhouses. The battens, intended to receive tiles or slates, are particularly adapted to the attachment of slates and flat or "mechanical" tiles.
It is an assembly of boards nailed, preferably contiguously, on the rafters or trusses. This type of roof support was widely used for nailing slates (now abandoned). It remains relevant for the laying of the canal tiles in the south of France.
Initially, it consists of panels nailed on the chevron or the fermettes: plywood (quality CTB-X), particle board (quality CTB-H) or insulating composite panels carriers. This technique is now widely used for sarking, thermal insulation from the outside of roofs.
The choice depends on the style (imposed in some sites) and the slope of the roof.
Used since antiquity, terracotta tiles remain the first of the materials used for roofing in Western Europe. Made with a clay-siliceous mixture, pressed or extruded, then dried and finally baked, they are divided into three main standardized categories:
- flat tiles;
- interlocking or sliding tiles;
- Channel tiles.
Appeared in Bavaria at the end of the XIXe In the last century, concrete tiles have been rapidly established in northern Europe and the United States. They are an alternative to terracotta tiles, which they take models (except for the tile channel).
Natural and artificial slates
Natural slates are one of the noblest roofing materials, especially in many historic sites, as well as for steep roofs. They are required in highly rainy ocean regions.
The exhaustion of natural slate veins led to the creation of artificial slates in fiber cement. Pigmentation in the mass is necessary to prevent any risk of discoloration.
The slate are thick slates and often large. In metamorphic or volcanic rocks, they impose, because of their weight, a very solid framework.
They are bitumen pressed on a textile frame. Invented in North America in 1883, shingles became the first roofing material on the New Continent. The improvement made in France in 1964 with the use of a glass fabric reinforcement marked the expansion of this material in Europe.
The corrugated sheets were long confined to the cover of agricultural or industrial buildings. They exist in fiber cement and fiber-bitumen. The former are used mainly for the coverage of agricultural and industrial buildings. Bituminous sheets are primarily intended for garden shelters and recreational buildings.
Ventilation and sealing
The airtightness of the current roofs (imposed by the RT 2012) and the presence of various insulating complexes in the roofing make it necessary to provide ventilation and, in many cases, to protect it, by a screen of sub-roofs. roof, against infiltration of slush and dust.
It avoids the risk of condensation on the lumber, which promotes the growth of fungi and provides an ideal ground for the establishment of termites or xylophagous insects. The ventilation is provided by elements with openings and by the arrangement of air passages at the base of the roof and in the vicinity of the ridge. The total area of these air passages shall be at least 1 / 5.000 of the projected area of coverage in a horizontal plane, when it does not have an insulating screen. With a screen, this proportion should not be less than 1 / 3,000.
The waterproofing between the roof and the roof improves the protection of the roof and is strongly recommended under a roof with a low slope, as well as in a structure located in a very exposed climate site. It is ensured by a screen placed on the chevron:
- decking in particle board or plywood;
- a screen made of terracotta elements;
- a reinforced polyethylene film.
|Materials||Slope min.||Maximum altitude recommended||per m²||Support||Common use|
|Flat roof tile||35||70||1500 m||42||70kg||battens 18/27||carved roofs|
|20||36||1,200 meters||15||45kg||battens 27/40||single roofs|
|Roman tile||20||36||800 m||32||70kg||flutter + battens lengthwise||rustic roofs|
|Natural slate||20||36||-||20-60||30-80kg||doves + battens||all roofs|
|Artificial slate||15||26||-||10-75||20-30kg||doves + battens||very exposed roofs|
|Corrugated fiber cement||11||20||1,000 m||-||17kg||60/60 battens||industrial roofs|
(photos / visuals: © DIY-Prod, except special mention)
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