Abstract: There is described a building component in combination with one or more spacers. The building component comprises a base element adapted to be positioned on a surface of a building structure and a pair of mutually spaced side members which project from the base element to define a longitudinal channel for the receipt of a supporting batten to which a further surface layer may be secured. The building component is adapted to allow the insertion of the or each spacer between the base element and the supporting batten in the direction transverse to the longitudinal channel.There is also described a spacer comprising a base section and a pair of mutually spaced side walls in which the base section of the spacer is adapted to overlie the base element of the building component and extend transversely of the longitudinal channel.There is also described a building component comprising one or more frangible regions spaced at intervals along the length of the channel.