The task:

The existing drawings of you object no more describe the actual situation. Due to changes, that occur constantly nearly in every building, walls have been moved, doors and windows have changed, etc.    

You need however a current documentation of your building for renting and maintenance. 

This documentation shall contain an accurate area computation according to GIF or DIN 277, so that you can be sure that the spaces  

specified in your rental contracts are correct.

Also for the front of your building you would like to have accurate drawings showing the surfaces, in order to maybe rent part of the front surface for advertising purposes.     

Current sectional drawings of the object should be just as available as also a room catalog with space sizes, room heights, door lists, wall and ceiling material, etc.