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How and when did slate develop?

Approximately 400 million years ago in the Devon time on the bottom of primeval oceans the finest clay mud deposits developed and under high pressure and temperatures they gradually solidified into claystone. During the later mountain formation these layers of claystone were folded up by lateral pressure. During this process of the so-called foliation a sequence of microscopically fine lamellose minerals (mica layers) were formed and the slate owes them its typical structure and characteristica – in particular the good splitting property and weathering resistance.

What is actually Moselschiefer®, InterSIN® and/or ColorSIN® ?

Moselschiefer® comes from the mines Katzenberg and Margareta and for many centuries it has been a term for top slate quality. Already round about 1850 the original transport route via the Moselle River gave the much sought-after building material its name. The historical choice of name has established itself as a term of quality.

InterSIN® is our international trade mark for slate from the best international deposits. When selecting the exploitation sites we orientate ourselves to the high quality of the Moselschiefer®. The processing quality is checked every day on site.

ColorSIN® is coloured slate in the shades purple, red brown, ruby red, grey-green, dark green, leaf-green, light green and lime-green.

By now this slate is also coming from international deposits since the corresponding national deposits have been exhausted a long time ago.

What different claddings (formats) are available?

Old German style cladding, wild cladding, Schuppen (fish scale) cladding.

Bogenschnitt (curved cut) cladding, rectangular cladding, decorative cladding with Spitzwinkel (pointed angle), decorative cladding with Fischschuppen (fish scale), decorative cladding with Waben (honeycombs), decorative cladding with octogons, decorative cladding with coquettes 

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Why does Rathscheck Schiefer produce the old German style cladding only from Moselschiefer® ?

The old German style cladding is considered the queen of all claddings and already during processing it requires the specific skill of a craftsman. It is in accordance with the century-old roofing tradition in the German language area. It is a specific capital of only a few German slate companies to have the trained personnel capable of freehand producing the old style German slate group in three typical shapes (blunt, normal and sharp cut). Freehand processing a prerequisite of the old style German cover slates: Every single slate is different in its height and width and thus a carefully processed unique specimen.

This, also in its processing an unusual type of cladding, deserves a special high-quality material as the Moselschiefer® certainly is. For these reasons it suggests itself that the old style German cladding is produced on site from local Moselschiefer®.

Is slate really as expensive as it is often assumed and how does the price-performance ratio compare to the one of other roof building materials?

Today slate is more reasonably priced than its reputation. On the one hand this is due to new, more modern exploitation and production facilities and on the other to a great extent to a large number of new formats enabling more rational laying. As a result the labour costs can in parts be considerably reduced – finally having a positive effect on the overall costs.

How much is a square metre (m²) of completely laid slate?

The price always depends on the type of cladding, but also on local conditions (e.g. pitch of the roof, lengths of the rafters, number/shape of the dormer windows, chimneys, size of the space, etc.).

You will receive exact price quotations with regard to the individual object from your roofer specialised in slate or use beforehand our price calculation model and/or take a look at the price quotations for the products.

How long is slate durable?

Slate is a natural product. For centuries it has proved its worth on roof and wall of historico-cultural buildings and is hardly reached regarding aesthetics and service life. As can be proved there are service lives of 250 years and more for best slates (inter alia Eltz Castle, covered with Moselschiefer® in 1780: in 1986 after 206 years part of the claddings were renewed, only because the nails had eroded).

With regard to the subject durability an excerpt from the American slate standard is worth mentioning: >>Slate is normally considered the most durable type of roofing and, if correctly selected and properly laid, it may under certain circumstances be the most durable part of the building<<.

Is there also coloured slate?

Durable coloured slate in the shades green, red, purple and reddish-brown is only found very rarely in the world. The colours have a natural origin, i.e. coloured slate is marketed without any additions just like it was extracted from the bowels of the earth. More recently the company Rathscheck especially succeeded in obtaining with ColorSIN® raw materials from other continents with new attractive, natural colours for the German market. This provides additional creative opportunities for the builder/owner, the architect and the planner.

Where does the colour in the slate come from?

Conditional on the fine-grained structure the slate colours are often dark (by high optical absorption e.g. blue-grey) or conditional on additional natural chromophore components, green (by the green mineral chlorite) or red to purple (by the mineral haematite).

Is there also white slate?

Particularly in Thuringia and Saxony light slates can often be seen in old ornamental claddings; they are often called "white slate". This slate, however, obtained its light colour only in the course of time by continuous patination and ageing. Because if you split or break one of these white slates, you can clearly recognise its original light green colour.

In this respect, when restoring old ornamental claddings, light green slate, e.g. green ColorSIN® should be used in the preservation of historic monuments that is committed to the original condition.

Are there differences in quality between the various trade marks and/or exploitation sites?

No, because our different trade marks and/or exploitation sites have an integrated quality level. All the exploitation sites are specifically selected according to the quality characteristics of the Moselschiefer® - sometimes, such as for example for ColorSIN®, we had to search worldwide.

There are, however, differences in the processability or the surface structure, but this does not have anything to do with durability and/or difference in quality.

Why is there a strict separation between the individual exploitation sites at Rathscheck´s?

We strictly separate and mark according to the exploitation sites, just like the technical rules of the ZVDH (Central Association of the Roofers\' Craft) demand. According to the technical rules slates from different exploitation sites may not be intermixed. Why? Slate is a product of nature. Formed in a long process in the earth\'s history. Not every deposit has the same geological conditions. Slate is a rock with natural differences in colour and different surface structures. When using slate from different exploitation sites, the roof or the façade would look spotted.

Is there any asbestos in the slate?

Slate is completely free of asbestos, it does not contain any asbestos nor any other mineral fibres.

Is roofing slate radioactive?

No, roofing slate is not radioactive. The measured natural radioactivity existing everywhere is in slate even lower than in other rocks used for building purposes. In the former GDR, however, so-called "black slate" was exploited as uranium raw material. These slaty rocks, however, have nothing to do with roofing slate and they are also completely unsuited for the use on roof and façade.

Does slate burn?


What are the advantages of slate in comparison to other roofing products?
  • Long service life
  • On a long-term basis, i.e. in comparison between original costs and service life, extremely economical.
  • Highest storm resisting strength
  • Natural building material
  • No costs for waste disposal
  • Aesthetics (harmonious overall image?)
  • Individual
  • Hardly knows any architectural limits
What types of cladding/formats can be used on façades?

Basically all of them, at the same time certain limitations should be observed for individual formats:

With the old German style cladding and the Schuppen (fish scale) cladding the height of the cover slate shall be not more than 26 cm. with the rectangular cladding the limit is 40 cm.

In addition, however, there are special types of cladding and formats that are especially (and exclusively) suited for façades, such as the Bogenschnitt (curved cut) cladding 20/20 cm, Waben (honeycomb) 20/20 cm and special Fischschuppen (fish scales). 

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How much does one square metre (m²) weigh when completely laid?

On the roof approx. 30 kg, on the façade approx. 28 kg, in case of special claddings with a sharp cut 36 kg and with double cladding 45 kg. 

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For what pitches of roof can slate be used?

As from 22 degrees – here, however, a double cladding (old German style or rectangular) is required; all other types of cladding from 25 degrees onwards.

With a water-tight roof substructure it is, however, possible to stay below the regular pitch of the roof by 10 degrees. 

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When using slate, do you need a specific roof support structure for slate?

No, one needs a classic roof structure, therefore solid shuttering. Pre-covering is required, at least V13.

In case of a rectangular cladding it is also possible to fasten the slate directly onto the lathing with the cramping technique.

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How is slate fastened?

As a rule with three slate-fixing pins or nails made of rustproof metal, that is hot galvanised (with a minimum coat of 50 my), made of copper or stainless steel (V2A).

On the façade the slates up to a cover slate of 24 cm can be fastened with 2 nails.

In addition, it is possible to also use cramp hooks and/or pointed hooks (V4A) for the rectangular cladding. 

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Are there any texts for invitations for tender?

The texts for invitations for tender can be downloaded at the products, in the download sector or in the forums for architects and roofers.

Can you recommend roofer companies qualified for laying the slate?

We would certainly like to give you the names of roofers in your neighbourhood who are specialised in slate. Please send us an e-mail, we shall then help you.

From which dealers in roofing/building material can I obtain Rathscheck slate?

There is a large number of specialist roofing dealers who stock Rathscheck slate. We would certainly like to give you the names of dealers in your neighbourhood. Just send us an e-mail.

Why does Rathscheck not produce any ashlar (window sills, floor slabs, etc.)?

Since our extensive and very complex production range demands our full attention, we have specialised a long time ago in slate for the application "Roof and Façade".

How can slate be cleaned, e.g. cleared of moss?

For the environment\'s sake no chemical substances should be used, in most cases clear water and a brush will do. In case of large areas a steam jet blower can also be used with the necessary distance and low pressure. Incidentally, moss on the slate has nothing to do with the rock but with the location of the house.

Is the Rathscheck Schiefer Company open to visitors and/or can one inspect the two Moselschiefer® mines Katzenberg and Margareta?

We naturally make an inspection for certain groups of persons (exclusively specialist clientele) possible, because we aspire to also open ourselves to the outside world in this respect, to show our modernisations of the recent decades and to convey to a number of people as high as possible the unique event of the inspection of a Moselschiefer® mine.

The interest is very great – not only in Germany but also with regard to our partners and friends in all European countries. This tremendous demand, however, asks too much by far of our possibilities. At the same time it does not only concern the effects upon the production quantities and costs, but our staff is also only able within a certain time-wise restricted extent to welcome groups in addition to their actual management and marketing tasks.

What events take place and/or are there any training opportunities?

Rathscheck organises a number of different forums and symposiums specifically geared to the relevant target groups with regard to their type and extent.

Whether during the day of the roofer or the architect, the symposium of the specialist dealer or the slate or during the slate miners\' festival or the Mayen Roof Congress – here you will always learn something worth knowing all around slate – from the extraction via production and processing to laying and much more.

How much longer can Moselschiefer® still be exploited?

Supplies have been developed with an extraordinary range of time for slate productions have. The presently known resources safeguard the Moselschiefer® production far into this millennium.

How can one be sure to get good slate?

On account of many distinctive features provided by nature, slate is a matter for specialists. This requires a high degree of the buyer\'s confidence in his supplier which for this very reason can only be safely justified by proven specialists. Only vendors like Rathscheck Schiefer with experience over many years and an efficient control organisation for quality assurance on all levels of production and processing guarantee perfect slate in the end.

What is the most ecological building material?

A natural product such as slate naturally has a good hand in an absolute comparison of all building materials. There are different opinions what is after all the most ecological building product. However, the State Institute for the Building Trade of the state of Northrhine-Westphalia, Aachen, in an overall assessment of outer walls reaches the conclusion: "Slate ... by far the lowest use of energy and lowest CO2 / SO2 emission values in the group under comparison" ... "no negative effects with regard to environment and health".

Does slate help against electro smog?

There are customers who report it to us. After their roof had been covered for the first time with the natural product Rathscheck Schiefer, they could for the first time again enjoy their night\'s sleep although in the time before they after all suffered very badly from electro smog. We are, however, unable to exactly explain the phenomenon. But the fact is interesting that slate indeed has electrical insulating properties, because in former times it was certainly customary to make electric switchboards from slate. Today such works of art could not be paid for any longer, quite in contrast to slate roofs where recently reasonably priced possibilities have become available.

Does slate contain chlorinated fluorocarbons?

Slate is a natural product that approximately 400 million years ago was formed from very fine-grained clayey mud. Approximately 325 million years ago came the transformation of these sediments into clayey slate. CFC-compounds are man-made and thus did not play any part in the natural history of the origin of slate. For this reason roofing slates cannot contain any CFC-compounds. The very low contents of carbon and possible ore compounds appearing instead of them are "natural" and give no cause for concern. During its entire service life slate has therefore exclusively properties that are friendly to health and environment.

What does a green spot do in purple slate?

Now and again spots of different colours appear in coloured slates. They do not represent any limitations of quality, but were formed naturally.

Thus it is absolutely possible that a green spot appears in a purple slate or a purple spot in a green slate. When it is small, it will hardly be noticed. This natural phenomenon is an indication for the fact that ColorSIN slates in the colours green as well as purple are related in their emergence and may appear together in a quarry.

This phenomenon is natural and no problem at all!

Can such spots be sorted out?

In view of the natural emergence of slate this should not be done. Particularly such colour variations are an indication for the natural product slate. At times excessive uniformity is an indication for industrial products. Change and precisely colour variations, on the other hand, are typical for the material of a natural product.

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