ESDU 78036 gives equations that enable known solutions for the stress intensity factor in simple configurations to be compounded to give a stress intensity factor for a complex component. The stress intensity factor is affected by the presence of "boundaries"; the surfaces of the component, holes in it, stiffeners attached to it. The method takes account of the boundaries by breaking the component down into a group of ancillary configurations each of which contains the crack and one boundary, and for each of which there is a known solution. Two conditions are considered: with the crack crossing a boundary or not crossing a boundary. Comprehensive practical worked examples illustrate the application of the method.