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Building Products January 2018

COVER STORY | SSQ | ADVERTORIAL RIVERSTONE PHYLLITE: A QUALITY ROOF THAT STANDS OUT Here, Haroun El-Helw, Head of Marketing at SSQ Slate highlights the differences between slate and phyllite when used in roof covering applications. He also discusses what to look for when choosing a slate or phyllite to ensure a problem free slate roofing specification. SSQ owns and operates the Riverstone quarry in La Represa, deep in central Argentina, situated between the Pampas and the Andes mountain range. It is the only source of this type of slate locally, and there are only a few sources of phyllite stone available worldwide. Riverstone natural phyllite has a slightly coarser grain and a unique satin-like luster, making it the choice of the most discerning architects across the world. SSQ has been supplying the Riverstone product for the global slate and phyllite market for over 20 years. Slate is formed when mud rock is buried deep beneath the earth’s surface. On a tectonic plate boundary, the material encounters extreme pressure and temperature. Through a process known as metamorphosis, minerals within the original mudstone are altered over a period of 417-545 million years, creating modern day slate. 6 BUILDING PRODUCTS | JANUARY 2018 Phyllite in comparison is one step along in the metamorphic chain. Typically older at over 560 million years of age, it is also harder, denser and stronger than slate. It has been subjected to metamorphic processes over a longer period of time causing the original material to be more crystalline, crisp and coarse. Characterised by a phyllitic sheen and larger grain size, it offers specifiers an attractive alternative to run of the mill slate. It also benefits from impressive longevity with most roofing phyllites expected to last for over 100 years, meaning they often outlive the building itself. Riverstone roofing phyllite has a very low content of the usual problematic inclusions such as pyrite and calcite, making it a stable roofing product that will not colour or suffer from pitting. It is medium grey in colour, with a very slight tinge of green and has a rougher surface texture that imparts a more rustic feel to a new or refurbished roof. Scottish heavy slate sizes are available alongside traditional English and Welsh slate thicknesses. Riverstone has a reputation among planning and conservation bodies across the UK, established through its aesthetic similarity to many local slates, its high quality and, equally important, its value for money. It has frequently been used on projects where the volume of slate required or the budget could not be met by local sources. Like any building product, the prime concern for architects, specifiers and contractors when choosing natural slate for housing should be quality and this is not necessarily a given with natural slate. According to the National Building Specification (NBS) ‘specifiers are still finding it difficult to understand why slate that adheres to the current European standard can be so different in quality’. The current European slate standard EN 12326 was last revised and reissued in 2014 with the aim of providing further clarification on quality to suppliers, architects and specifiers, as well as A BRIEF HISTORY THE DIFFERENCE BETWEEN SLATE AND PHYLLITE THE PRODUCT TESTING WHAT YOU NEED TO LOOK FOR


Building Products January 2018
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