A composite constructional element 1 comprises a plank profile 2 defining a rear face 6 and two opposed edge sections 4 and 5 of the constructional element. Each edge section includes an edge face 4a,5a. A cladding material 3 is moulded into the plank profile to extend continuously between the opposed edge faces such that it is retained by the rear face and the opposed edge faces. The plank profile may further comprise retaining formations 4b,5d shaped to retain the moulded cladding material attached to the plank profile. A method of manufacturing the composite constructional element is also disclosed.