The invention relates to a thermal insulating element comprising an insulating layer having a first face and a second face, said insulating layer comprising a coherent man-made vitreous fibre-containing insulating material and at least one reinforcing element extending substantially from the first face to the second face of the insulating layer, wherein the reinforcing element comprises a polymeric foam composite material, the composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the polymeric foam composite material have a length less than 100 micrometers.