What are the principal advantages of using a single building information model of the existing conditions as the foundation for modeling proposed additions or renovations?
The advantages of using a single building information model are that you only model overlapping geometry once. This is important because it improves the ease and accuracy of the renovation / addition. You can clearly see where everything connects and what you have to change about the existing building, and it’s easy to update things because everything updates at once. Additionally, if you make a new model it becomes harder to show partial demolition or modifications.
What sort of complexities are introduced when you construct a building complex in phases?
A core challenge is physical connection; ensuring that each phase ties in structurally and spatially into the portions already built. There is more documentation to take care of (existing, demolition, new), introducing opportunities for error. In terms of the actual construction, things like columns and foundations have to be coordinated carefully as you add on other layers. You also have to make sure that new walls and roofs properly seal to previously built ones and that there are no mismatches in elevation.