I do ‘phased’ projects similar to jclewis’s method and Tenant Fitouts like gppowless too.
Over the years, I’ve found the modeling process ‘evolutionary’ as the design is developed. The single model existing in time as the master-design doesn't quite work as advertised. A single model reference in the form of documents for the Owner or Contractor maybe, but the Architect & Consultants would see their own design of that model differently.
Design & documenting projects w/ArchiCAD usually results in a series of models as the process unfolds or the design program dictates. ArchiCAD can handle this approach in so many different ways which is probably why GS stopped publishing ‘how-to ‘s as while ago.
Archiving or saving the project-model at specific points in the design process has been SOP, even before computers & CAD. If the design changes, retrieving a file is easier than re-modeling the project from scratch – even with ‘cutting & pasting.’
I use ‘find and select’ a lot on Tenant Fitouts to make the construction elements that are previously constructed look like ‘existing walls.’ That and layer management are key to managing involved designs. I’ve had projects were the Owner was marketing the same space to several tenants at once!
The real key is keeping your project-model files viable as the upgrades come along, but that's another topic.
Hope this helps…..
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Mac G5 Dual 2.3 Ghz, 1.5 Gb
Mac OSX.4.11
ArchiCAD 12 2782 USA Full + 11, 10, 9 & 7
Mark R. Wallace AIA
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MacBook 2.53 Ghz, Intel Core i5, 8 Gb,
Mac OSX (Sierra 10.12.6,
ArchiCAD 22 USA Full, +21, & 20.