The BS 5534:2014 ‘Slating and tiling for pitched roofs and vertical cladding – Code of Practice’, supersedes BS 5534:2013
Fixings of roof coverings:
The experience of recent weather patterns in the UK and Europe has resulted in changes to the theoretical wind loads used to calculate the mechanical fixing requirements of slates, roof tiles, ridge and hip tiles and roof systems. This means that roof tiles and fittings will, under this new Code of Practice, require more mechanical fixings.
The new Standard introduces minimum performance requirements for roofing underlays, together with a new test method for determining the wind resistance of unsupported underlay.
The test will measure the upward deflection of an underlay and potential movement at its overlaps, when subjected to air pressures likely to be experienced in the UK. This is to ensure that an underlay cannot displace under a given wind load to the point where it makes contact with and displaces the roof tiles or slates.
A new labelling system is introduced to indicate where an underlay is suitable for different batten gauges.
In the new Standard, no reliance is placed on the strength of the mortar to hold the roof components in place, meaning ridge and hip tiles will be required to be mechanically fixed.
The industry has been moving towards mechanical fixing by installing dry ridge and hip systems as a standard practice. Mortar will still have its place with traditional and refurbishment projects; but they will need to be used in conjunction with mechanical fix options such as clips, nails or screws. Details and information on how to achieve this should be available from the roof tile manufacturers.
The new Code of Practice became live on 1st September 2014. In doing so, a number of the major tile and underlay manufacturers have now produced guides to help understand the changes and help you choose the correct tiles, fixings and underlays for a given site location. To meet these new changes, all ridge and hip tiles must be mechanically fixed. Finally, all roofing underlay products having current third party product approvals (e.g. BBA, BRE or European Technical Approvals) will, from 1st March 2015 need to be checked to ensure they have been tested to the new standard when certifying underlays for their fitness for purpose.
British Standards – BS 5534: 2014