Editing faces (object) and not mess with UV coordenates

Hi,

I have a question, how can i edit a objects (faces) without change the UV info? example:

created a cube, assigned a material, and image. Uwrarp and everything is fine, but i want o edit and create new faces and not get a distortion in image, because some times i use it like a “blueprint” of the 3d object.

I work with architecture, and sometimes i work first in the drawings in my desk and scan it and i want o put on blender to create an 3D object and not the contrary.

i hope that i could explained well about my concern,

Thanks and happy new year!