This document provides guidance and rules to notified bodies (for fire dampers) allowing them to produce/validate an extended field of application report for fire dampers. This document identifies the parameters that affect the fire resistance of dampers. It also identifies the factors that need to be considered when deciding whether, or by how much, the parameter can be extended when contemplating the fire resistance performance of an untested, or untestable variation in the construction. This document explains the principles behind how a conclusion on the influence of specific parameters/constructional details relating to the relevant criteria (E, I, S) can be achieved. This document does not cover dampers used for smoke control. It is the intention that the application of this document makes it possible to identify which specifications to test to maximize the field of application. Some information on test programmes is given for guidance purposes.