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?
- Why not create a separate model for the new proposed design?
Using one integrated BIM model allows for a much clearer understanding of how the new design interacts with the existing structure. It keeps all the geometry, materials, and systems in one place, which helps avoid inconsistencies and reduces the risk of errors during coordination. It also makes it easier to analyze how the proposed addition affects things like circulation, structure, and utilities. In renovation projects, changes are often interconnected — so having one model helps maintain that continuity.
Creating a completely separate model for the new design might seem simpler at first, but it can lead to issues later when trying to align the two models. You’d have to constantly reference back to the original, which increases the chance of mismatches in elevation, grid, or shared elements. Using a single model makes updates and revisions much more efficient.
What sort of complexities are introduced when you construct a building complex in phases?
- What happens at the interfaces between the buildings as the phases advance?
- How can you plan and prepare for these complexities as your create your initial building model?
When a building is built in multiple phases, the main challenge comes from how each phase connects to the others – structurally, mechanically, and visually. For example, interfaces between phases might involve temporary walls, partial utility systems, or spaces that need to stay functional during construction. These transitional zones often require extra detailing to ensure that when the next phase begins, everything lines up correctly.
To manage this, the initial building model should already account for future phases. That means defining clear reference points, grids, and shared elements early on, and organizing the model with proper phasing settings. Thinking ahead about where future additions will tie in, both physically and in the BIM file, can save a lot of rework and confusion later.