The disclosure relates to a profiled sheet comprising a web formation having first and second opposite ends; a first panel segment extending generally transversely from the web formation at or towards the first end thereof and a second panel segment, extending generally transversely from the web formation at or towards the second end thereof. The first and second panel segments extend in opposite directions from the web formation and the sheet further comprises a lip formation extending generally transversely from the first panel segment at an end defined by the said panel segment distal to the web formation and extending in a direction towards the plane wherein the second panel segment is located.
