Roofing battens - graded or ungraded

How do we know what roofing battens to buy and specify? 

New house building regulations insist on battens graded to BS5534. The NHBC have stated that all materials delivered to site must meet the correct standard and it isn’t the job of the installer to grade materials. 

This has resulted in the misconception that it’s OK to use un-graded battens everywhere else. Every material used within the roof meets a British Standard. Tiles, slates, underlays and fixings all meet their respective British Standards; timber is graded to C16, C24 or TR26 for truss Rafters. 

All construction timber is graded, with the exception of roofing battens. Is it right to use ungraded battens? The cost may be more but is this really fact? Battens outside new house building, especially NHBC, are still almost exclusively ungraded. Most contracts, commercial or domestic, require the roofing to meet BS5534. BS5534 sets out the requirements for battens but doesn’t state where the grading takes place. The HSE only recognise graded batten as giving a secure foothold when working on roofs. This gives the roofer two options: Buy ‘factory’ graded battens or ‘Grade on Site’. What are the pros and cons?

Factory Graded Battens

These are typically coloured. This clearly identifies that the batten is graded. Graded is either visual or by machine. Machine grading is usually by a combination of lasers and camera scanners. A third party accreditation usually forms part of the factory process control. Waste is minimal with only a check for end splits that may occur post grading and cutting back to the nearest rafter.

Ungraded Battens or ‘Grade on Site’

These battens may or may not be fit for purpose. They need checking for:

Dimension
Knots
Wane
Distortion
Slope of grain
Rate of Growth
Splits and fissures
Insect attack, rot and decay
Resin pockets
Once all these have been checked and measured on every batten along the whole length (not just a sample). Every batten must be marked and identified with:

Supplier
Origin or Timber Species
Size
BS5534
Done correctly is this a practical option? There are the following additional costs:

Time to grade
Time to mark every batten
Increased waste
Regardless of the cost, there are other risks. Increased health and safety risk and a risk in compliance – Why take the chance?

The batten may not give a secure foothold
It may not carry the imposed loads
Will not meet NHBC requirements
May not meet Competent Roofer requirements
May not meet specifications (contract or tile company)
May not be complaint with guarantees.
The only way to avoid these risks is to buy factory graded batten.