In the case of ceiling soffits with complex geometric boundary conditions, e.g. in the case of height changes or material changes, in the case of elemental suspended ceilings or in the case of requirements for the exact location of built-in components, the ceiling soffit with all boundary conditions is often shown in its own plan, the ceiling mirror. The graphic representation is carried out room-by-room as a projection (reflection) of the ceiling soffit downwards. Relevant components and furnishings from the floor plan are sometimes also displayed, e.g. in order to be able to position a luminaire in the middle above a table or in the axis of a door/window. Depending on the project, a ceiling mirror may contain the following information in particular:
In the ceiling mirror, cross-discipline axes can also be defined to which the built-in parts of different trades align together, e.g. recessed luminaires and ventilation outlets.
The exact position of e.g. axles or built-in parts is often not measured with numerical values, but with pitch ratios, e.g. 1/3, 1/3, 1/3 to arrange two luminaires in the thirds of a ceiling axis, or with small letters (a, b, c, ...) for identical dimensions in each case. For example, the arrangement takes place exactly in the actual middle of the room, regardless of dimensional deviations from the plan, e.g. due to construction tolerances.
Example excerpt from a ceiling mirror with metal panel ceilings made of top layer components of different widths and smooth plaster ceilings
Source: bauwion
