Stone Surface Materials

Basic info is found in Chapter 7.

Natural stone in the form of slates is well-suited for roofing as well as wall cladding and floors. Tiles, slabs and sheets cut from limestone, marble, syenite, sandstone and granite can be used as a floor finish, and as internal and external wall cladding.

Slate was used for roofing in France as early as the thirteenth century on castles, palaces and churches. The material was later widely used in many parts of Europe, including on homes and more simple buildings. However, the use of slate materials has declined since the beginning of the twentieth century. Seen from an environmental and functional point of view, few materials can compete with slate. In highly exposed areas it can successfully be used for cladding on all exterior surfaces, probably as the most robust alternative. Slates for roofing and cladding are usually cut into small sizes by simple splitting and dividing; slates for floor coverings are most often supplied as squares or rectangles.

Cut and polished stone products have been used increasingly during the twentieth century, especially in public buildings. Most of the stone types used are not strongly layered and, therefore, need a more advanced cutting and production technology than in the processing of slates. Floor tiles of granite, limestone and marble are usually produced in thicknesses of 2 to 3 cm, whilst sandstone may be cut to around 8 to 10 cm thick because of its lower strength. All stones can be polished, which simplifies maintenance.

The occurrence of slates and other stones for tiles is reasonably plentiful and well spread. They are most often extracted from open quarries, with the consequent landscape impacts and possible disturbance of local ground water and biotopes. The energy use in extraction and production processes is initially quite low, but naturally rises the more the stone is cut, worked and polished. Since stone is heavy, the transport energy involved makes it difficult to justify hauling it long distances from its source - which is often the case. Although slate is still fairly widely produced in Europe, cut stone and marble used in Europe today has sometimes been shipped from Asia or South America.

Certain types of stone containing quartz and dust can be a risk during the working of the stone (see Table 7.3). Slate, limestone and marble have negligible radioactivity and are no problem for the indoor climate. Certain types of granite can present a problem as a source of radon gas.

Most stone floors are easily looked after, durable and resistant to water and other liquids. Marble reacts with urine. Stone floors can be hard and cold, unless floor heating is used.

External claddings of limestone can be affected by urban pollution. Unprotected porous sandstones can easily be damaged by heavy rain and frequent freeze-thaw cycles. This could become more serious in Northern and Eastern Europe as a result of climate change.

Slate and stone tiles laid in a weak mortar or fixed mechanically can easily be taken up and re-used. Often over 90% of the slates from an old roof can be re-used, once the few slates damaged by frost, moisture and dismounting have been subtracted. All stone waste can be useful as a rubble fill, or for other purposes, and dumping stone waste is not necessarily an environmental problem unless it is in large quantities.

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