Roof coverings; roofing not of metal; roofing sheets of plastics material; corrugated and other profiled roof sheeting of plastics; polycarbonate roofing sheets and cladding including such sheets of corrugated, ribbed and other profiles; moulded and/or extruded polycarbonate sheet roofing and cladding; non-metallic building materials including gutters, fascias, capping, paneling building panels, walling, roofing, lattice, cladding, roof sheeting, wall and roof interface panels, skylight panels, skylights, and parts and accessories for the aforementioned goods included in this class and not of metal; extruded and/or moulded thick polycarbonate sheets for building purposes which are either flat, or profiled in cross section; multi-wall and multi-skinned polycarbonate sheets having a top, bottom and sides defining an internal chamber or chambers; extruded and/or moulded hollow multi-wall polycarbonate sheets including such sheets having chambers and/or flutes for the length of the sheet/s, all of the aforesaid goods optionally used in the construction of products including skylights, weather walls, privacy screens, roofing and cladding