Roofing Battens Advice

 

Roofing-Battens.pngWhether you are building a new house, refurbishing an old property or would just like to replace your old and tired looking roof, you will be making a choice from a wide and diverse range of roof coverings which are available on the market.
 
Your final choice should be based not only on the aesthetics of the roof, and how it matches your property, but also very importantly, on the performance of the roof. Its primary function is to provide a protective and weatherproof covering for your house and all its valuable contents. That’s why the substrate to which the roof covering is fixed should be chosen correctly. Most people don’t even think about the roofing battens (also called laths) as they are hidden by the roof covering, but they perform vital functions on the roof:

Battens have a specific standard and quality requirement and this is explained in BS 5534.
 
  • They are a structural element of the roof and give rigidity to the structure, particularly when modern trussed rafters are used.
  • They are primarily used not only to locate the roof covering in straight, consistent rows but critically, to provide a strong anchor for the nails and clips used to secure the tiles or slates. A sub-standard timber batten may not provide sufficient pull-out resistance for the fixing nails, leading to subsequent failure of the roof.
  • They are load bearing and must be strong enough to carry the “dead loads” (weight of the roof covering and possible standing snow) and “imposed loads” (wind) of the roof. Did you realise that an average house roof covered in concrete interlocking roof tiles carries approximately 5 tonnes of concrete on it?
  • The HSE Guidance Note, HSG 33, states that the only safe method of working on a roof with rafters set at 600mm centres (typical for new build) is by using graded battens to BS 5534.
The rules governing the types of roofing batten allowed are all contained within the British Standard Code of Practice for Slating & Tiling, BS5534: 2003+A1:2010 which specifies the type and size of timber to be used for different rafter spacings and roof coverings, and any defects that can and cannot be allowed.
 
 
Batten-Sizes.png
 
The section size of the batten is very important. Any batten measuring less than 25mm in thickness is classed as “under-measure” and should be rejected as it could be unstable and unsafe.
 
As well as size, the British Standard deals with various other defects typical to timber, which the roofing contractor has to consider when sourcing his material. These include:
  • Wane.
  • Slope of Grain.
  • Face knots and side knots.
  • Resin Pockets.
  • Insect attack.
  • Rot and decay.
  • Splits and fissures.
  • Preservative treatment.
In addition, each piece of batten has to be clearly marked with the following:
  • The name or identity of the supplier.
  • The sectional size.
  • The timber species type.
  • The grade of the batten/Graded BS 5534.
If you are installing your own roof covering, then any of the reputable roofing batten manufacturers or suppliers in the UK will be able to advise you on all of the above.
 
A good roofing contractor will be familiar with sourcing the correct batten and has three choices of material:
 
Factory-Graded.pngFactory graded batten – often coloured red, this is batten which has either been mechanically or visually graded at source and is guaranteed to meet all the performance requirements of the British Standard without any further time-consuming grading on site by the roofing contractor. This also means less waste, making it a very cost-effective option.
 
Part-Graded.pngPart graded batten – the most common type of roofing batten used in the UK. If a high quality timber is sourced, from a reputable manufacturer, the batten normally only requires a final grade on site by the roofing contractor to ensure that it meets the requirements of the British Standard.

There are a variety of grades of batten and to meet the requirements the contractor needs to mark each batten to show it has been graded to BS 5534.  Many re-roofing projects now fall within building regulations.

 
Ungraded batten – usually home grown species and requiring involved grading on site to remove all the defects listed above. Often sold cheaply, it represents a false economy as the waste produced by the grading process is very high. It is not recommended that this type of batten is used for roofing.

Did you know that if a roof is built with poorly graded battens (i.e. ones that do not meet the requirements of BS 5534) that it is almost certainly will invalidate any warranties such as NHBC or Co-Partnership?


Ask your roofing contractor for evidence that the batten he is using is either fully factory graded or that his “method statement” includes details of how his operatives will grade the battens on site to match the British Standard. You should also request a copy of the batten manufacturer’s treatment certificate which should show that it complies with BS8417:2011 and guarantees the battens for a period of 60 years in normal use.
 
 
 
Contact The NFRC
The National Federation of Roofing Contractors Ltd,
Roofing House,
31 Worship Street,
London,
EC2A 2DY
Tel: 020 7638 7663 
Fax: 020 7256 2125
 
 
John Brash

 

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