Executive summary
Revisions are a large share of permit workload. Without change detection, the reviewer either re-reads the full set or relies on the applicant’s revision list, which may be incomplete.
Revision intelligence compares submissions and reports what was added, removed and modified — sheets, notes, dimensions, schedules and, where models are submitted, objects and properties. It narrows attention. It does not decide whether a change is material.
Why revisions deserve their own treatment
A revision arrives with a different risk profile from an initial submission: most of the design has already been reviewed, and the open question is what changed and whether the change affects previously satisfied requirements.
Answering that by re-reading is expensive and inconsistent. Answering it from the applicant’s revision note is faster but relies on the applicant having listed everything, which is exactly the assumption a reviewer cannot safely make.
How change detection works
| Input | Comparable | Limitation |
|---|---|---|
| Vector PDF | Text, dimensions, line work, sheet structure | Layer and object identity may be absent |
| Scanned PDF | Visual differences at page level | Text and dimension comparison unreliable |
| Native CAD | Layers, blocks, entities, attributes | Depends on drawing standards discipline |
| IFC model | Objects, properties, spaces, relationships | Requires consistent classification and stable identifiers |
| Schedules and tables | Row and value changes | Layout changes can mask value changes |
| Annotations | Added, removed and edited notes | Reworded notes may be semantically identical |
Keeping the reviewer in control
Change detection produces a candidate scope. Two safeguards keep it safe. The reviewer can expand the scope at any point, and the system reports its confidence and coverage — including where it could not compare reliably, such as a scanned replacement sheet.
Implications for authorities having jurisdiction
Require stable sheet identifiers and revision numbering in submission standards. Comparison quality depends on it, and the requirement improves manual review as well.
Record the re-review scope decision with the file. If a later question arises about what was examined after a revision, that record is the answer.
Implications for applicants and professionals
Submitting revisions in the same format as the original, with unchanged sheet identifiers and an explicit change list, produces the fastest possible re-review. Replacing a vector set with scans removes the department’s ability to compare precisely.
Where models are submitted, preserving object identifiers between versions is what makes model comparison meaningful, and it is a modelling discipline rather than a software feature [1][2].
Risks, limitations and safeguards
- Missed changes are the primary risk; coverage and confidence must be reported, and reviewers must be able to widen scope.
- Cosmetic differences can flood the list; classification and filtering are required for it to be usable.
- Comparison across formats is unreliable; treat a format change as a full re-review trigger.
- Applicant change lists should be cross-checked, not trusted as the scope.
- Focused re-review must be recorded, including what was excluded and why.
PermitAssure perspective
PermitAssure compares submissions and maps detected changes to the requirements and findings they affect, then presents a proposed re-review scope with stated coverage. The reviewer accepts, expands or rejects that scope, and the decision is recorded with the file.
Five key takeaways
- Revisions carry a different risk profile and deserve a dedicated workflow.
- Change detection narrows attention; it must not decide materiality.
- Comparison quality depends on stable identifiers, consistent formats and modelling discipline.
- Coverage and confidence must be reported, including where comparison failed.
- The re-review scope decision belongs in the record.
References
- Industry Foundation Classes (IFC). buildingSMART International. www.buildingsmart.org. Accessed 3 August 2026.
- openBIM. buildingSMART International. www.buildingsmart.org. Accessed 3 August 2026.
- National Building Code of Canada 2025. National Research Council Canada. nrc.canada.ca. Accessed 3 August 2026.
- Guidance for Regulators on the Use of openBIM. buildingSMART International. www.buildingsmart.org. Accessed 3 August 2026.
Cited statements follow the sources above. Frameworks, diagrams and interpretation in this article are PermitAssure's own.
Related resources
Next step
Add stable sheet identifiers and revision numbering to your submission standard, then test comparison on a recent revision pair.
See revision comparisonPermitAssure provides digital review, workflow and decision-support capabilities. This resource is educational and does not constitute regulatory, legal, architectural or engineering advice. Final interpretations, approvals and regulatory decisions remain the responsibility of the applicable Authority Having Jurisdiction and its authorized professionals.