what is a furring strips
In construction, furring (furring strips) are thin strips of wood or other material to level or raise surfaces of another material to prevent dampness, to make space for insulation, or to level and resurface ceilings or walls. Furring refers to the process of installing the strips and to the strips themselves. Firring is a U.K. term for wood strips which are usually 50 mm wide, tapered and fixed above wood roof joists to provide drainage falls below roof boarding.