Practical checklist
What this article covers
A provenance and uncertainty log connecting each assumption to supplied survey/photos, decision owner and affected views.
An existing-conditions assumptions register records interpretations that the available evidence does not fully establish. Its purpose is to stop a provisional modeling choice from becoming an unexplained apparent fact.
Keep an assumption separate from a confirmed observation, a scope exclusion and a design proposal. This recommended register organizes review; it does not validate the assumed condition.
Write the assumption as a testable statement
Identify the affected model objects or drawing locations, the available reference, the unsupported part of the interpretation and the use that depends on it. “Verify on site” is not enough without saying what needs verification and who owns the question.
Autodesk describes using point clouds as an existing-condition reference. An authored Revit representation and its source evidence should remain traceable rather than treated as interchangeable.
Keep evidence and permission in separate columns
| Register field | Entry guidance |
|---|---|
| Assumption ID | Stable reference carried into affected outputs |
| Proposed interpretation | Exact provisional statement, not a vague concern |
| Evidence basis | Dataset, drawing, image or response and its revision |
| Uncertainty | What the evidence does not establish |
| Dependent use | Task that would rely on this interpretation |
| Review owner | Person responsible for deciding permitted treatment |
| Allowed treatment | Recorded instruction, including use limits |
| Verification and result | Method assigned by the responsible team and actual outcome |
Do not invent confidence percentages or turn “approved for a limited draft” into “verified existing.” A project instruction may permit a representation without proving the physical condition.
Hypothetical example: an unreadable room sign
In this fictional documentation task, an old drawing calls a room “Store,” but a supplied photograph does not make its current sign readable. The proposed label “Store” is recorded as an assumption based on that drawing, not a confirmed current room name.
The review lead requests a clear, authorized reference for the name. Until it arrives, the working output identifies the unresolved label under the project's chosen convention. It is not silently treated as a confirmed source for other schedules.
When a current reference establishes “Archive,” record the evidence and update the affected locations. Retain the old assumption and its resolution rather than rewriting the history as though the name was always known.
Ask for the right evidence without prescribing site work
For an MLX capture, NavVis's quality-map checklist distinguishes panorama sharpness and distribution from other scan checks. That vendor-specific guidance illustrates why the supplied evidence type matters; it does not prove that any particular sign or concealed condition was captured.
Ask the responsible project or survey lead to determine permitted follow-up. Do not direct a remote drafter to enter restricted areas or infer an unseen assembly.
Close the assumption only on a recorded basis
Use outcomes such as verified by identified evidence, replaced by a recorded decision, or still unresolved with a stated use limit. Check dependent outputs after a change.
The drawing discrepancy log is more suitable when two identifiable records disagree. Carry open assumptions into the model acceptance checklist.
Nest's scan-to-BIM brief guide and scan-to-BIM support provide broader context for discussing source information and production responsibilities.
Related guides and services
Keep the production handoff connected to the wider workflow:
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