Build a baseline that answers early decisions
Collect available drawings and records, then compare them with current site evidence. Identify the spaces, levels, structure, openings, and services that affect the planned work. Use measured surveys where those relationships need confirmation. Retain the dates and sources so the team can understand the baseline's scope.
Prioritize information around design choices. A proposed access route may depend on opening dimensions and changes in level. A new plant location may depend on retained services and installation access. These questions help target capture and investigation before effort is spent modeling areas that do not influence the project.
Keep uncertainty visible during option development
Distinguish verified geometry from information taken from records or assumptions. Maintain an investigation register with a location, reason, responsible role, and decision deadline. This allows an option to proceed with an understood qualification instead of quietly treating unknown construction as established fact.
Avoid adding unsupported material layers or concealed service connections to make the model appear complete. Where an assumption influences the viability of an option, show that dependency in the review. The team can then decide whether to investigate, allow flexibility, or select another approach.
Represent the sequence of retained and new work
Agree how the model will distinguish retained construction, removals, new elements, and temporary arrangements. Revit's phasing tools can associate elements with project phases and use filters to control their display in views and schedules. Set the approach before several teams start producing renovation drawings.
Check the resulting views as communication documents. A demolition plan, an interim arrangement, and a completed layout should each be understandable. Where an occupied building changes in stages, review access and interfaces at those intermediate stages rather than checking only the final arrangement.
Coordinate at the boundaries of old and new
Focus coordination on the connections between proposed work and retained construction. Review opening positions, floor transitions, service connections, equipment replacement routes, and areas where several trades share limited space. Include the appropriate specialists when the decision depends on structural or building-services performance.
For a hypothetical refurbishment, a new air-handling unit may fit its final room while its delivery route remains too constrained. Review the route, handling sequence, and required temporary removals as separate questions. The example illustrates why a final-position model alone does not settle construction feasibility.
Update the evidence as the building opens up
Renovation can reveal information that was unavailable during the first survey. Plan opportunities to record exposed construction and newly accessible spaces before work conceals them again. Review those observations against the model and issue changes through the agreed coordination process.
Keep the original baseline and subsequent revisions traceable. At handover, reconcile the installed work, accepted changes, and remaining exceptions into the final record. The value of renovation BIM depends on this controlled updating, because a well-prepared starting model can quickly become misleading if site discoveries remain in separate notes.
Common questions
Should the whole existing building be modeled first?
The scope should follow the renovation's interfaces and likely decisions. Some projects need broad context; others benefit from focused detail with clearly defined boundaries. Agree expansion triggers if the work changes.
Can old drawings replace a measured survey?
They can provide valuable context, but their currency and reliability need checking. Use current site evidence to confirm the relationships that matter to design, coordination, and installation decisions.
Further reading
This article was rewritten in October 2026 around the subject of the original Geobiro post. The original publication date is retained; the update date identifies the current text.