Natural slate is recognized throughout the world as one of the finest building materials available. The material has a capability to withstand the most extreme environmental and weather conditions. Its durability and unique natural beauty has led to the specification of slate in a broad range of roofing applications.
Slate is frequently grey in colour, however, slate occurs in a variety of colours even from a single locality and can be found in many shades of grey, from pale to dark. Ninety percent of Europe’s natural slate used for roofing originates from Spain with Brazil, China, Argentina and the UK being some of the most used slate in the UK.
Slate is particularly suitable as a roofing material as it has an extremely low water absorption index of less than 0.4%. Its low tendency to absorb water also makes it very resistant to frost damage and breakage due to freezing.
Slate roof tiles are usually fixed using either nail fixing or the hook fixing method as is common with Spanish slate. Nails will traditionally be copper, although using S/S hook fixing means that areas of weakness on the slate are fewer since no holes have to be drilled and is particularly suitable in regions subject to severe weather conditions since there is a greater resistance to wind uplift as the lower edge of the slate is secured.
The metal hooks are, however, visible and may be unsuitable for historic properties. Both these methods, if used properly, will provide a long-lasting weathertight roof with a typical lifespan of around 80–100 years.
BS EN 12326-1:2004 is the harmonised EU standard governing Natural slates and all slates, irrespective of their origin, should be tested to the criteria laid down in the standard, and thus have a set of test results and should carry the CE Mark.