A Batten is a strip, usually consisting of wood, plastic or metal, which is used to fix roof tiles or a roofing sheet into place. Please note that battens are only required when covering a sloping roof - it is their job to prevent any covering from slipping off.
Many Battens are used together. They are positioned so that they overlap with one another, forming a 'horizontal' line (parallel to the slope of the roof) across the surface of the roof. There will be several rows of these horizontal lines into which tiles can be fitted or a roofing sheet pinned.
Occasionally, 'counter-battening' is employed whereby overlapping Battens are also positioned to form 'vertical' lines up the roof, creating a grid on the roof's surface.
Should I install my own battens?
If you are pondering this question then the answer is perhaps 'No!' Fitting Battens should only be attempted by someone with construction experience. It is a tricky job which, if performed inadequately, could lead to serious leaking and structural damage.