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BP 10 October 2016

NEW BUILD & SOCIAL HOUSING UPLIFTING RESPONSE What are the implications of the revised BS5534, and why do architects and designers need to understand this latest standard? Ged Ferris has the answers. Since 1942, the British Standards of Codes of Practice have existed to provide guidance for those engaged in the design and construction of buildings. In those 70 odd years, the BSI Group has published many thousands of standards and today there exist over 27,000 in total. The Codes of Practice exist to provide a degree of uniformity in the quality for goods and services available and based on a mixture of scientific data and practical experience. They can evolve over time and are updated when necessary. The British Standard for Slating and Tiling, BS5534, is a key Code of Practice for the roofing industry and was updated in August 2014 and has been mandatory since the end of February 2015. There are three main areas of change to the BS5534. The main areas affect the practice of mortar bedding, underlays and fixing. Of the three main areas of change the one which is likely to have the most impact is the higher theoretical wind uplift calculations that will need to be made to ensure compliance. The main driver for this is the increase in the instance of extreme weather events we have been experiencing in the UK in recent times. Hurricanes, wind-driven rain and flooding have all become more common, and all can exact a price on the built environment in general, and especially roofing. Furthermore, the update brings the UK into line with the rest of the EU as the equivalent standards on wind uplift have been traditionally been tougher on the continent. The changes to wind uplift calculations in BS5534 have an impact on how roof coverings are fixed. This significantly affects the fixing of single lap tiles which will all have to be fixed with a clip or nail. In effect, the practice of tiling will fall into line with slating. The need to fix each slate in place with a hook or nail is something that the slating trade understands and is standard practice. This process takes longer for obvious reasons and adds time to an installation, and the upshot of this is that the generally perceived time-saving benefits that tiles have traditionally enjoyed over slates no longer exist. Good workmanship is the foundation of a successful slate roofing project or indeed all roofing projects and using the correct fixing method is an essential part of the project. There are two methods for fixing slates – nail and hook. Using the hook fixing method for slates has been popular in Europe, particularly France, for the past 50 years. It is becoming increasingly popular in the UK and can be used for both natural and fibre cement slates. When hook fixing is the chosen method, it is important to check the quality of steel and thickness of hook used as there are hooks that will 16 BUILDING PRODUCTS | OCTOBER 2016


BP 10 October 2016
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