Slate covering is the covering of a roof or a facade with clay slate ; the result is a slate house . Here, roof and facade slate as a roof covering applied to a top surface that is usually made of wood. Hot-dip galvanized, hammered or forged slate nails, stainless steel screw pins or copper nails are used to fasten the slate.
Split natural stones were used for roofing as early as the Stone Age . It is proven that the Romans used roofing slate for the first time in a closed association with fixed laying rules for roofing. Slate roofs from this time or built according to Roman laying rules can still be found today, for example in the Rhine and Moselle areas.
The slate craft flourished in the Middle Ages. During this time, most of the high-quality buildings were covered with slate.
After the Second World War, industrial products replaced slate more and more.
At the beginning of the 1980s, slate experienced a renaissance in the wake of the "ecological building" movement. The renaissance of slate began in the mid-1970s with the development of inexpensive and decorative cover types. Above all, this reduced the degree of difficulty and the workload of the deck types. Today there are around 15 types of decking and well over 250 design options.
In Germany, training to become a slate roofer is still offered at the Federal Education Center (BBZ) for roofers in Mayen .
Old German coverage
The old German cover is offered as a normal cut, sharp cut and blunt cut and laid with a pitch. The incline of the container is intended to ensure that the water that occurs is drained away from the cover. The pitch of the container depends on the roof pitch (the steeper the roof, the lower the pitch). The peculiarity of the old German cover is expressed in the fact that cap stones of different heights and widths are used and the bundles are tapered from eaves to ridge. Depending on the rafter length, the difference between the largest and smallest container height is 40 to 80 millimeters.
Characteristics are stones of different sizes, which are laid in such a way that the smallest cap stones are used on the ridge and the largest cap stones on the eaves ( with the greatest amount of water ). This makes the roof look nicer and higher. Due to its variability, the old German roofing is particularly suitable for demanding and complicated roof geometries. It is also called the "queen of decking types" and is a difficult and technically demanding type of decking.
Wild cover is one of the most extraordinary types of cover. The slate stones are delivered to the construction site uncut and the roofer then prepares them individually for the corresponding roof. Basic properties of the wild cover are used by the old German slate cover. This type of deck is very complex and requires a great deal of manual skill.
The individual stone has the same geometry as the old German cover. However, all stones in this cover are of the same height and width (templates). The roof looks just as elegant as an old German roof, but is more flat and more even overall.
The further development of the arched capstone (square plate with asymmetrical arched cut and a heel) is generally referred to as the universal capstone. For the first time, the square universal capstone has a symmetrical corner rounding with two heels and a corresponding edge processing.
While different cover stones were required for the right and left cover for the classic curved cut cover, since the development of the universal cover block, both right and left cover can be carried out with one and the same block. In addition, the universal capstone can also be used as a third option standing on the arch (facade covering). Realizing these three laying directions for the first time with just one capstone was only possible due to the new corner symmetry, the resulting two heels and the indispensable edge processing.
Since the development of this new universal cover stone, the so-called universal cover has been one of the cheapest types of cover.
Curved cut coverage, German coverage
For arched cover, also known as German cover, square slate with an asymmetrical arched cut, left or right, is used. For right coverage you need panels with the arch on the left, for left coverage the arch on the right is required. The cover direction (right or left) depends on the prevailing weather direction.
The decorative cover types include fish scale cover, pointed angle cover and honeycomb cover.
The rectangular cover is ideal for cladding large facades. The clear lines and the orderly structures of the cover image harmonize particularly well with a modern, functional architectural style. There are many variants of the rectangular cover, for example the drawn cover, the rectangle double cover, the horizontal cover, the variable cover or the underlaid cover.
Rectangular double cover
The rectangular double roofing with its straight, clear lines goes very well with modern buildings. It is considered to be technically simple and extremely solid. Due to the pointed, Gothic or round cut shapes of the rectangular stones in their visible surface, there are various design options, despite the rectangular basic format. It is also known as the English cover because it was imported from England in the 19th century. It was originally due to the thick English slate, which can only be cut in a rectangular shape. Later it was also used for German slate because the rectangular cut was the easiest.
More regular coverages
In addition to these classic types of cover for the roof, there are also some decorative types of cover for the roof and facade. These are, for example, coquettes, octogones, honeycombs, pointed angles or fish scales.
The gap thicknesses, formats, cover types and quality requirements, which differ greatly from country to country, are tradition.
- In Germany, the highest demands are usually made on slate. This applies not only to the material properties including the standard gap thickness of 4 to 6 mm, on average 5 mm; The selection of formats (around 250 models) and the variety of cover types also show the different design requirements in Germany.
- In France, on the other hand, life expectancy or service life expectations, color stability, design and thus aesthetics are not so important. You are satisfied with 10 to 15 rectangular formats, whereby, depending on the region, only 2 to 3 formats are common. The gap thickness is only 2.5 to 4 mm, which is made possible by partly more favorable climatic conditions and simpler fastening methods. The high standardization of the slate formats , combined with the smaller gap thickness and a simpler type of laying (rectangular double roofing), allow the costs of a slate roof to drop to such a level that the building authorities can stipulate slate in entire areas without encountering resistance from the building owners . In the case of historical buildings and public works, the regulation generally applies to use slate produced by France.
- Great Britain only knows the rectangle format. Aesthetic aspects are taken into account with historical laying techniques through different widths and heights of the rectangles. The gap thickness corresponds to the German technical rule, but is also exceeded due to production. Large formats are generally preferred.
- Wolfgang Dürr: How to cover a roof with slate , SWR TV - Landesschau Rheinland-Pfalz , series: Handwerkskunst! 18 July 2017 (YouTube on April 24, 2019) documentation on the example of a house in Daaden in an old German slate cover, .
- Schieferlexikon - information on the origin, structure and occurrence of slate; Explanations of standards
- Slate trade association