Is there a minimum % of new floors, walls, ceilings, etc. for a major renovation of an existing building under NC-v4?

Hi Craig, have you looked through the guidance published by USGBC? https://www.usgbc.org/articles/rating-system-selection-guidance. They include a 40/60 rule towards the end that might answer your question. Generally I'd say that O+M has a very different focus than the design and construction rating systems, so stepping back and deciding what your goals are first, and then figuring out which rating system supports those goals, might be a good way to approach it.