BS 5534: 2014 ‘Slating and tiling for pitched roofs and vertical cladding – Code of practice’, supersedes BS 5534:2003 which still remains current during a transitional period starting from 1st September 2014 until 28 February 2015 when it will then be withdrawn.
This Standard is intended to be read in conjunction with BS 5250, BS 9250 and particularly BS 8000-6 so now allowing both Standards to complement each other whereas before there were conflicts in the information they contained.
In the forward section to the new code of practice it identifies that it is a full revision of the standard, and includes a complete re-structuring. The COP states:
Updated information relating to the preservative treatment of timber battens has been contributed by the Wood Protection Association (https://www.thewpa.org.uk/).
Product certification: Designers and specifiers are advised to consider the desirability of using roofing products, fittings and accessories that are supported by recognised UKAS-accredited third-party assessment.
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. For example:
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.
We have had many claims for mortar bedding on a roof cracking or breaking due in mainly to poor workmanship. This leaves the ridge or hip tiles vulnerable to dislodgement in high winds. Therefore, in the new Standard, no reliance is placed on the strength of the mortar to hold the roof components in place and 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 though, e.g. with traditional and refurbishment projects; but they will need to be used in conjunction with mechanical fix options such as clips, nail or screws, with details and information on how to achieve this being available from the roof tile manufacturers.
Sadly, it reflects the change in climate we now have but also it’s a result in tightening up in standards of workmanship.
A number of the major tile and underlay manufacturers have now produced guides to help understand the changes and choose correctly the tiles, fixings and underlays for a given site location.
The new Code of Practice became live on 1st September but a transitional period until 28th February allows Developers to adopt the still current 2003 Code of Practice.
For sites with our Warranty in place, the requirements in our Technical Manual in particular; Appendix c – materials products and Building systems and Section 11 Roofs must also be met e.g. All ridge and hip tiles must be mechanically fixed.
Moving forward; 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.
September 2014
Since the above technical update was written a further revision has been made to BS 5534. BS 5534:2014 + A2:2018 was published on February 28th 2018 and introduces several amendments, as well as clarifications of the scope of the Standard. Following a four-month transition period, this standard became effective from July 1, 2018.
BS 8612: Dry-fixed ridge, hip and verge systems for slating and tiling – specification, has now been added into BS 5534. This means that under BS 5534, only BS 8612 compliant dry fix systems are suitable for use. Not using one would be in breach of both of the standards.
The addition of the phrase ‘for normal re-roofing work, including repairs’ has been added to the scope, to make it absolutely clear that re-roofing and repairs are covered under BS 5534.
There have been a number of site issues where lightweight underlays have not been installed correctly, in particular the degree of drape when laid unsupported over rafters. As such, BS 5534 introduces several changes and roofing contractors need to make sure that underlays are installed correctly in accordance with the new recommendations:
Roofing contractors should also take note of some new advice for fixing baby ridge and hip tiles. These are only recommended for low level roof details, such as bay windows and porches, no higher than 3m and may be bedded using only mortar, subject to self-weight being sufficient to resist the wind loads. This maybe a suitable approach for Warranty purposes, providing that the site can provide suitable evidence of the self-weight being sufficient to resist the wind loads and the correct mortar specification is used.
Outlined above are the main changes to BS 5534: 2014 + A2 2018, a full list of the changes can be found in the forward to the standard, available using from the Construction Information Service website.