Skylights, skylights incorporating ventilation, roof vents, windows, window assemblies and units, diffusers for skylights (translucent building panels), non-metallic frames for skylights, non-metallic skylights for buildings, plastic skylights, skylights (windows) of non-metallic materials for use in buildings, skylights made from plastic materials for use in buildings, skylights not of metal (windows), translucent building materials for skylights, bituminous products in sheet form for waterproofing roof surfaces, concrete roof repair compounds, glazed roof panels (non-metallic frame), mounts of concrete for roof windows, mounts of plastic for roof windows, mounts of wood for roof windows, non-metallic panelling for roof gardens, non-metallic prefabricated roof structures, non-metallic prefabricated roof units, non-metallic ready mountable parts for roof constructions, non-metallic roof components for buildings, non-metallic roof coverings, non-metallic roof lights (windows), non-metallic roof panels, non-metallic roof vents, non-metallic roof windows, non-metallic vented underlays for roof waterproofing systems, plastic roof plate, roof coverings made of fibreglass, roof coverings, not of metal, roof elements made from building glass, roof elements made from structural building glass, roof elements made from wood, roof fanlights (windows) of non-metallic materials, roof flashing, not of metal, roof non-metallic materials, roof panels made of cement, roof panels made of cement reinforced by natural mineral fibres, roof panels made of cement reinforced by synthetic fibres, roof panels made of concrete, roof windows made of inorganic materials, roof windows made of plastics