Timber battens or roof slats hold roof tiles in place. They can be manufactured in a choice of species and sizes, although there is less flexibility than there once was.

Following revisions made in 1997 to the BS Code of Practice for Slating and Tiling (BS5534: Part I), timber battens are now categorised into two types - "A" and "B":

• Type "A" species covers imported red and whitewood
• Type "B" covers homegrown species, such as Sitka Spruce

Also, changes have been made to the UK timber sizes of battens which must be used, and there are new grading rules, as well as a "no minus" tolerance in thickness. This latter requirement should remove the costly risk of contractors inadvertently using battens cut 1 or 2mm undersized.

The issue of roof batten quality applies to refurbishment as much as new build. Lack of awareness of these revised changes to timber battens is no longer acceptable.

Some timber batten manufacturers will supply helpful - free - guidance on the new recommendations for roof battens. Some have also introduced a new marking system to fully comply with the new guidelines.

If in doubt about these important regulations, ask for guidance from your supplier.