Clip lock sheets is designed to be fastened to roof purlins or wall girts with fixing clips which are concealed during fixing and do not require any fastening holes through the steel sheets. The double capillary break design of the interlocking mechanism of adjoining sheets ensures the prevention of ingress of rainwater by capillary action. As the side lap contact area of the profile is minimal and is well ventilated, trapped moisture cannot remain and the danger of overlap corrosion is eliminated. From security point of view as fasteners are concealed, roof sheets cannot easily be removed from outside.