Battens are thin strips of wood (or other material) fixed at right angles to the rafters or trusses of a sloping roof, to provide fixing points and support for the tiles or slates.
Battens may also be fixed to felt roofs to cover joins in the felt and to prevent wind-action lifting the felt.
Modern roof tiles have projecting nibs or ridges on their underside which hold the tiles in place when laid so that the nibs rest on the roofing battens. Slates and some types of tiles without nibs have to be nailed to the battens to keep them in place.
Wooden battens are subject to decay and damage caused by water, woodworm and rot. If this happens the tiles or slates will come loose, damaging the integrity of the roof. Loose tiles and slates can also be dangerous if they fall onto passers-by or neighbouring property.
In modern homes battens are fixed over roofing felt (see bituminous felt) and so cannot easily be inspected. A survey report will note if tiles are loose, which may be evidence that the battens need renewing.
In new homes, or when a home is being re-roofed, battens should comply and be fixed in accordance with BS5534.