This document gives guidance and requirements for the design and calculation methods, installation, acceptance testing, routine testing and maintenance for pressure differential systems (PDS). PDSs are designed to hold back smoke at a leaky physical barrier in a building, such as a door (either open or closed) or other similarly restricted openings and to keep tenable conditions in escape and access routes depending on the application. It covers systems intended to protect means of escape e.g. staircases, corridors, lobbies, as well as systems intended to provide a protected firefighting bridgehead for the fire services. It provides details on the critical features and relevant procedures for the installation. It describes the commissioning procedures and acceptance testing criteria required to confirm that the calculated design is achieved in the building. This document gives complete rules, requirements and procedures to design PDS for buildings up to 60 m. For buildings taller than 60 m the same requirements are given (e.g. Table 1), but additional calculations and verification methods are necessary. Requirements for such methods and verification are given in Annex D, but the methods fall outside the scope of this document [e.g. Computational Fluid Dynamics (CFD)]. Routine testing and maintenance requirements are also defined in the document. In the absence of national requirements and under expected ambient and outside conditions, the requirements in Table 1 are fulfilled by the PDS.