A building code issue caught in design costs a conversation. The same issue caught on site costs a defect claim, a failed inspection, or an awkward call with the client. The expensive part is rarely the issue itself. It is when the issue gets found.
On most projects, compliance is still checked late: at certification, at inspection, or once trades are already on site. By then the cheap fixes are gone. This article looks at why code issues slip through to construction, what that timing costs architects and builders, and how AI plan checking moves the check back to the drawing board, where problems are cheap to solve.
This is not a niche concern. With NCC 2025 now in effect and more scrutiny on energy, accessibility, and fire provisions, the gap between a drawing set and the current code is wider than many teams assume, and the cost of finding that gap late has not gotten any smaller.
Why do code issues slip through to site?
They slip through because the volume of checking outpaces the time available to do it by hand. A residential drawing set runs to dozens of sheets. NCC 2025 runs to thousands of clauses, and that is before a single state variation, referenced AS standard, or client QA spec is added. Three things make manual checking break down at scale:
- Volume. Every revision means re-checking the set, and most projects revise many times before submission.
- Fragmentation. The information lives in different places: a dimension on the drawing, a material in a schedule, a fire rating in a spec, and the rule itself in the code.
- Timing pressure. The checking happens at the end, against a deadline, which is exactly when attention is thinnest and the cost of a miss is highest.
There is also version drift. Codes change between editions, and a detail that passed under NCC 2019 can fail under NCC 2025. A project started against an older edition, or carried over from a previous job, can hold non-compliances that nobody introduced on purpose. Catching those needs a check against the current code, not the one the office used last year.
What does catching an issue late actually cost?
The later a non-compliance is found, the more it costs to fix, because more work has been committed on top of it. The same missed clause is a quick redraw in design and a demolition order on site. Here is how the cost of one finding climbs as it moves through a project:
| When it is found | What it looks like | Relative cost |
|---|---|---|
| Design | A markup and a redraw | Lowest |
| Pre-submission | An RFI or a coordination fix | Low |
| Certification | A resubmission and a delay | Medium |
| On site | Rework, a failed inspection, or a stop-work notice | High |
| Post-completion | A defect claim or rectification order | Highest |
Take one example. An egress door that is 50 mm too narrow is a one-line correction on a plan. The same door, found by an inspector after the frame is in and the wall is lined, becomes a variation, a delay while it is reworked, and a re-inspection. Nothing about the requirement changed. Only the cost of meeting it did.
The lesson is not that people are careless. It is that the workflow pushes the check to the most expensive possible moment. Move the check earlier and the same finding becomes trivial to resolve.
Where should building code compliance be caught?
As early as the information to check it exists, which on most projects is the drawing set. The geometry, the schedules, and the model are all present long before anything is built, so the first real opportunity to verify compliance is at the drawing board, not the slab.
In practice the responsibility is shared. Architects and designers can verify a set at the design stage before it leaves the studio, and builders can validate documentation before work starts, including the trade and shop drawings that come in from subcontractors. The common thread is that both want the surprise to happen on paper, where a fix is a markup rather than a rectification order.
Catching issues early helps everyone downstream, too. A set that reaches a council or a certifier already cross-checked and cited moves through review with fewer rounds and fewer requests for information. That is part of why the same workflow is useful to building surveyors and authorities, not only the teams that produce the drawings.
How does AI plan checking change the timing?
It makes a full check cheap enough to run early and often, instead of once at the end. A check that used to take hours of manual cross-referencing takes minutes, so there is no reason to save it for the deadline. The workflow is straightforward:
- Upload the set. PDF drawings and the IFC model are read together, so the data behind the BIM and IFC model is checked, not only the lines on the sheet.
- Choose the code. Check against NCC 2025, the IBC, a council requirement, or your own internal QA standards. If you can upload the document, it can be checked against.
- Ask or audit. Ask a question in plain English, or run a full pass and fail audit across the whole regulation.
- Read a cited report. Every finding points to the exact clause and the exact sheet it came from.
For a deeper look at the extraction step, see our guide on how AI reads a drawing set and a BIM model.
Because a check is fast, it can run at every milestone rather than once at the end: at concept to sanity-check the big moves, at developed design, and again before submission. Each pass is a fresh, full audit against the current code, so issues surface while they are still cheap to fix instead of accumulating quietly until handover.
What can you check across a project?
Compliance is not one thing, so a useful check spans the domains a surveyor would work through. Across a typical set that includes:
- Fire safety - fire-resistance levels, separating walls, egress paths, and detection.
- Structural - load paths, bracing, member sizes, and footing details.
- Energy efficiency - insulation, glazing performance, and star ratings.
- Accessibility and livability - door widths, ramp gradients, and clearances.
- Light and ventilation - window area against floor area, sill heights, and safe glazing.
- Waterproofing - wet-area membranes, termination heights, and flashing.
The regulation is not hard-coded. You can check against the published code, a specific council requirement, or your own internal QA standards by uploading the document you want to be measured against, which is what makes the same workflow useful from concept design through to handover.
Why do cited findings matter more than answers?
Because an answer you cannot verify is a liability, not a tool. A compliance report is only useful to a professional who has to sign off if every line of it can be traced and defended. That is why each finding is cited to the specific clause in the regulation and the specific page or element in your drawing or model.
A compliance report is only useful if you can defend every line of it. Citations turn an AI answer into evidence you can hand to a certifier.
This also keeps the human in the right place. The tool assists the architect, builder, or surveyor who signs off; it does not replace their judgement. It just means they review a cited shortlist instead of starting from a blank page.
Citations have a second benefit: they create a record. When every finding links to a clause and a sheet, you have an audit trail of what was checked, against which code, and on which revision, which is useful if a question about a decision comes up months or years later.
What changes for architects and builders?
For architects and designers, the value is catching issues before drawings leave the studio: fewer RFIs, fewer revisions, and fewer questions about why a clause was missed after submission. A quick pass at developed design can flag an energy or livable-housing gap while the plan can still absorb the change cheaply, so the set that reaches a certifier is one you can stand behind. The detail is on the page for architects.
For builders and contractors, the value is validating the documentation, and the incoming subcontractor packages, before work starts. Running a trade or shop drawing against the relevant code and your own QA standards before it hits the slab protects both the program and the margin, and a cited report gives you something concrete to resolve with the designer or certifier rather than a hunch. The cheapest defect is the one you never build. The detail is on the page for builders.
How do you start?
You can check your first project for free. The free plan includes 65 credits and full platform access with no credit card required. Upload a set, choose the code, and read a cited report in minutes. See pricing, or create a free account and run a check on a live job today.