Subtracting the area of windows and doors from a wall gives its net façade area. To place an order you also need panel quantities and lengths. An opening of a few square metres may cut through several panels or align with panel joints. Its area is the same in either case, but the delivery list can differ. Here is how to turn an elevation sketch into a schedule of panels, cuts and trims that you can compare with the manufacturer's quotation.

Ordering sandwich panels requires a description of the conditions on both sides of the enclosure. An external façade faces different exposure from a hall interior, and rooms within the same building may be used differently. Choosing colour and thickness therefore does not settle questions about facings, coatings, details and upkeep. This guide helps prepare a description for the designer and supplier: temperature and humidity, cleaning methods, local contamination, possible damage and planned changes of use. It does not assign one coating to every workshop or warehouse. The aim is to identify the information needed to assess a particular solution and record its limitations before ordering material.