Revised version of BS5534 published
BS5534 has been revised to make UK roofs more secure in the face of increasing extreme weather events, and will be mandatory from the end of February 2015.
The new British Standard dictates that every tile will have to be mechanically fixed with a degree of clipping required on most roofs. Additionally, tiles at the perimeter of a roof must now have a minimum of two fixings.
BS5534 also states that mortar alone is no longer deemed sufficient on its own to secure tiles and their associated fittings to a roof. This will mean areas including ridges, hips and verges will now require mechanical fixing as well. Marley Eternit anticipates that this will lead to an increase in dry fix systems.
Gavin White, product manager at Marley Eternit, said: "Whilst a roofer, installing to the British Standard, can still use mortar, they will only be able to do so with the addition of a mechanical fix. Consideration also needs to be given to ensure a suitable roofing mortar is created through the correct sand and cement mix; this is also outlined in the standard.
"The restrictions now in place surrounding the use of mortar, and in particular, the extra cost that comes with the addition of a mechanical fix, will likely result in a further shift towards the use of full dry fix systems. These not only provide a mortar and maintenance-free way of fixing, but also, in many cases, contribute towards ventilation required to meet BS5250."
The standard also introduces new requirements to secure lightweight underlays and prevent a recent problem of 'ballooning', caused by wind deflection, which has been known to place a load on the underside of the roof covering, capable of dislodging it. According to Redland, the European product standard for underlays does not address this issue, so even the presence of a CE mark does not mean that an underlay complies with the Code of Practice. The new Code therefore introduces a single test for the measurement of wind uplift resistance, which all testing bodies will be required to follow.
In anticipation and support of the revised standards, Marley Eternit has introduced tools and products to help contractors and builders meet the additional fixing requirements.
Gavin White, product manager at Marley Eternit, said: "This is the most significant change to the way roofs are fixed in the UK for years and it is an important step in ensuring a consistent standard to withstand future extreme weather events and bring us into line with the European equivalent. While these changes will predominantly affect roofing and building contractors, those selling and specifying roof products also need to be aware of the consequential effects of the new standard, as there are products which can be used to reduce the additional time and cost which could be incurred as a result."
The importance of industry knowledge has been reiterated by Redland's marketing manager Kevin Horne, who said: "The revised Code of Practice is significantly different to what has been the baseline standard for roofing practice in the UK. It is vitally important that all in the industry - specifiers, merchants and contractors alike - are fully up to speed on what the key changes are and what they will mean for their business."
The revised BS5534 was published on August 31 and there will be a six-month crossover, or coexistence period, where the two standards will be available to use.