BS5534 is still a game-changer for the roofing industry

Nov 29, 2019 Off Comments in General News by
BS5534 is still a game-changer for the roofing industry

The introduction of BS5534 was a real game-changer for the roofing industry when it came into force. SR Timber’s Trading Director Shaun Revill looks at the impact it has had on timber roofing batten.

When it was launched, British Standard BS5534 (which as revised in 2018 to be BS 5534:2014 + A2:2018) – which set out a new code of practice on slating and tiling for pitched roofs and vertical tiling – was welcomed with open arms by some, accepted by most and begrudged by a few. There’s one thing nobody can deny – it was, and remains, a game-changer for the industry.

Before we look specifically at the impact it’s had on batten, it’s worth reminding ourselves of the key areas that the standard covers:

1. Fixing specifications

The introduction of the structural Eurocodes has seen greater emphasis placed on the calculation of wind speeds as part of pitched roof construction. All single-lap tiles should be mechanically fixed using a clip, a nail or a combination of both. And double-lap plain tiles and slates used in exposed areas may require enhanced mechanical fixings in the form of stainless steel nails or screws.

2. Underlay

Vapour resistance and resistance to wind uplift are the two key factors when selecting underlay, as stricter recommendations for the securement of the laps of the underlay and a new labelling system have been introduced. Only underlays suitably labelled and meeting the new standard should be installed. Fixing penetrations through the underlay should not be subject to enlargement caused by shrinkage or nail tear as a result of wind uplift loading, and they should be sealed where required to prevent water ingress.

3. Mortar

Mortar is now deemed to have no tensile strength, so any tensile bond strength offered by the mortar bedding of concrete or clay ridge, ridged hip, verge and valley tiles should not be taken into account when determining the mechanical resistance required to resist wind uplift. All mortar-bedded components should be supplemented by mechanical fixings to secure them to the roof structure where the wind uplift load exceeds the dead load resistance.

4. Timber roofing battens

The standard clarified the rules around the quality of materials, the grading of batten and the documentation that accompanies it. During production, roofing battens are piece stamped with their dimensions, timber species code and certification such as the Q-Mark denoting independently assessed third-party quality assurance. As a reminder, pre-graded battens should be accompanied by documentation that includes:

  • Name of the supplier
  • Origin and/or species code
  • Grade in accordance with BS 5534:2014 + A2:2018
  • Basic size or sizes
  • Type of preservative and method of treatment, if applicable

When it comes to batten, we’ve done all the hard work so that roofing contractors and general builders don’t have to – so the impact has actually been negligible. The introduction of BS5534 only served to ratify the best practice that had been adopted by responsible producers around the grading and quality of timber roofing battens long before the standard came into existence.

The strength of the supply chain
The ability to provide a consistent supply of BS5534-compliant batten comes down to having a robust and sustainable supply chain.

The Baltic states have been deeply impressive in coming from humble beginnings to become a global powerhouse in producing top-class products. Latvia is one country that has got serious about batten production, which is a move that has come from the top. In this case, ministers in the Latvian government have fostered a collaborative approach with key businesses such as sawmills to help to maintain a plentiful supply of high-quality raw materials to meet current demand. They also have an eye firmly fixed on the long term and take issues of sustainability very seriously, which ensures that the next generations will also have access to high levels of raw materials.

This gives reputable companies with a long-term vested interest in producing BS5534-compliant batten for the UK market complete control right the way through the process, from the forest, to the sawmill and to the roof.

Beware of imitations
Sadly, wherever you get suppliers who work hard to produce quality, compliant products, you’ll also get materials that are cheaper and don’t meet the standard.

One of the best tell-tale signs of correctly graded roofing batten is that it is a minimum of 25 mm in thickness (the British Standard stipulates a minus tolerance of zero and a plus tolerance of 3 mm). We have seen instances of supposedly graded batten as thin as 23 mm, which fails the British Standard requirement in dimension before you even start to look at other aspects of quality.

And, while I’m on my soapbox, I must make mention of the myth that sideboards are the best part of the log to produce batten. There’s no justification for that because the strength of timber varies throughout every tree in a forest, and it can even vary within different parts of the same tree. Therefore, so long as any piece of timber does not exceed the specified limits of the grading rules, it is irrelevant which part of the tree it may have come from. In other words, provided that batten meets the requirements in respect of all significant strength-reducing defects (knots, slope of grain, rate of growth, etc.), then it must be proper batten.

Grading is the key to great batten
So, now that’s out of the way, the most crucial part of the production process and the real game-changer has been grading. Every single piece of our roofing batten is inspected and graded to ensure that the product conforms to British Standards. We check to make sure that no defective material/

It makes sense to us that the complete process is done in one place, so logs enter one part of the production plant and arrive at the other fully graded and BS5534 compliant – ready for UK distribution, finally ending on roofs throughout the United Kingdom.

BS5534 has no doubt been a game-changer – but not for us because we were already playing the game the right way in the first place.

This article was first published in Building Products magazine.