(57) A building component is described comprising a moulding adapted to be secured to the top surface of flooring joists either along the length thereof or transversely thereacross, having a rebate along its length to provide a ledge on which a floorboard edge can rest. The depth of the rebate accommodates at least the thickness of the floorboard, and the thickness of the moulding below the ledge creates a services void between the floorboard and the upper surface of the joists. The moulding may also include a second parallel rebate leaving a ridge therebetween. The two floorboards are spaced apart by the ridge. A further rebate can be provided to accommodate at least part of another member. Where a floor covering is laid over the floorboards the rebate(s) is/are sufficient to accommodate both boards and covering. A floor panel including such mouldings comprises a plurality of spaced apart joists secured at their ends to rim boards, elongate mouldings secured to the joists, flooring boards located on the rebates and secured to the mouldings, to create a void between the floorboards and the tops of the joists. A services supporting platform is formed by flat panels between and supported on the lower flanges of parallel I-beam joists.