Hi Speaking from experience, I would imagine it would be when the Principal Contractor's contract ends and the building/site is handed over to the client (and occupied?). I have been on sites where one PC finishes before the finishing off works (e.g. electrical, decorating, comissioning etc) were completed, and the building was not habitable, so the PC role was transferred, and the info for the file passed over. It can get messy! I think the client must have a big part to play in deciding if the construction phase is over, as it is them or their tennant that must then take responsibility for it. However, we don't do the construction element of NEBOSH Diploma until next week so I may stand corrected! Kind regards Kay