Roof beams with positive engagement between cross bar and lower capping

A roof beam for use in forming a conservatory roof, comprising a glazing bar and upper and lower cappings fitted thereto the glazing bar being of generally inverted T-section providing a cross bar and an upstanding limb, the cross bar having a central section and edges in the form of side walls extending above and below the central section to form a recess in the underside of the glazing bar and bottom edges of the side walls having formations thereon for positive engagement with the lower capping, the lower capping comprising a channel section with co-extruded gaskets along edges thereof fitted over upper parts of the side walls.