The client does not have to calculate the purlins themselves in order to order the structure well. They should, however, understand what they are paying for and which data influence the choice. Cold-formed profiles offer a wide variety of cross-sections and methods of preparation. Z-sections, C-sections, sigma and omega profiles can complement one another in a single building. The decision is not about choosing the most attractive shape. It is about finding a complete solution for a specific function. At the outset it is worth defining how the facility will be used. A dry warehouse has different needs from a workshop, a cold store or an agricultural building. The differences concern loads, cladding and environment. Planned installations and future changes should also be taken into account. Such information helps the designer select the layout before a list of profiles for pricing appears.

A precise enquiry saves time for both parties to the order. The supplier does not have to guess parameters, and the client receives quotes that are easier to compare. Cold-formed profiles are best described as specific parts for a defined task. Z-sections, C-sections, sigma and omega profiles require more data than just the name and the total linear metreage. A well-prepared list helps move from a general idea to a predictable delivery. It is worth attaching a drawing with the height, flange widths and bends. The sheet thickness is also needed. For sigma profiles, the shape of the web matters, and for omega profiles, the width of the central part and the flanges. A Z-section may have different flanges on either side. The full geometry makes it possible to establish which product is meant without having to interpret an abbreviation in the message.