A method of assembling of a door comprising the steps of providing a door inner panel having an outer face and an inner face, at least one functional component of the door, an anti intrusion beam and a door outer panel. The functional component is assembled onto and towards the outer face. The anti intrusion beam is assembled towards the outer face prior to assembling the door outer panel towards the outer face. Fixing means secure the door inner panel, the functional component, the anti intrusion beam and the door outer panel relative to each other.