One company supplies the main structure, a second the profiles and a third the cladding. Such a division can work smoothly if the scopes meet at clearly described points. Most misunderstandings arise at the connections. Cold-formed profiles require screws, brackets, splice plates and stabilisation selected for the project. It is worth establishing who prepares them before comparing final tender prices. A general phrase such as 'purlin supply' does not say whether it includes the connection to the frame. It may cover just the Z-sections or a complete system with accessories. This must be stated explicitly. It is worth using a drawing of a typical connection detail and assigning the parts to suppliers. Then each party sees what it is responsible for and which element it must connect to.