TL;DR
Structural teams should evaluate Scan to BIM providers on connection capture (terrestrial setups at tie-ins, not mobile-only), LOD specified by system rather than globally, real structural families instead of in-place masses, a stated accuracy backed by a registration report (±5mm registered, 8–12 mm to control), named business-day turnaround, native cloud formats alongside the model, and a contractual acceptance test at 90% dimension pass and 95% completeness.
Most Scan to BIM marketing is written for architects. Structural engineers reading it end up buying an architectural deliverable and discovering, three weeks in, that member sizes were modelled generically, connections were not captured, and the analytical model has to be rebuilt from scratch.
The evaluation criteria below are the ones that separate a structural-grade provider from a general one.
1. Do they capture the connections?
The difference between an architectural scan and a structural scan is almost entirely about what happens at joints. A column line modelled from a mobile scan at LOD 200 tells you where the column is. A retrofit connection design needs the gusset plate, the bolt pattern, the weld access, and the actual flange dimension.
Ask directly: will terrestrial setups be placed at connections, or is the entire building captured mobile? Our own practice pairs mobile capture with terrestrial setups at tie-ins — on a 220,000 sq ft plant retrofit, that meant 38 RTC360 setups placed specifically where connections mattered, inside a 5-day field program covering the whole facility.
2. Is LOD specified by system, or globally?
A provider quoting "LOD 300 everything" is either overcharging or about to under-deliver. Structural work needs a split:
- LOD 300 on primary structure — columns, beams, braces, foundations where exposed
- LOD 400 on the 5–15% where new steel meets existing steel
- LOD 200 on architecture you are not designing to
That split is the entire cost lever. On a 180,000 sq ft Mansfield conversion, LOD by system cut modelling hours 28% against a blanket LOD 300 spec. On a 92,000 sq ft Columbus conversion, a targeted split saved 9 business days and $65,000 in avoided change orders. The full breakdown lives in LOD 200 vs 300 vs 400.
3. Do they hold members as real sections or as generic masses?
Ask to see a sample Revit file. Look for:
- Structural framing families with real section designations, not in-place generic models
- Members placed on levels and grids that match the project, not floating geometry
- Consistent work plane and orientation so the analytical model is not garbage
- Connection geometry as modelled elements where LOD 400 was specified
A model that looks right in a screenshot and is built entirely from in-place masses is worthless for anything downstream.
4. What accuracy do they state, and can they prove it?
The number must be in millimetres and it must come with a registration report. Reasonable answers on building-scale work:
- Registered cloud accuracy ±5mm
- Interior registration residuals 2–4 mm RMS, exterior 4–6 mm
- Absolute accuracy to project or state plane control 8–12 mm
- Model within ±10–15 mm of the cloud at LOD 300
Ask whether registration used closed loops and how many control points. A 250,000 sq ft distribution center held ±6 mm on five closed loops and 40 control points; a 480,000 sq ft, twelve-building campus held ±0.02 ft (±6 mm) on 47 permanent control points across 18 acres. Numbers like these should be available on request. If a provider cannot produce a residual report, the accuracy claim is marketing.
5. Can they work around your operations?
Structural retrofits happen in occupied buildings more often than not. Ask about night shifts, phased capture, and access coordination. Real examples: a 38,400 sq ft active med-surg hospital wing captured in two overnight shifts with no disruption to patient care, and a live distribution center captured in 4 days with zero operational downtime.
6. What is the turnaround, stated in business days?
Vague turnaround is a scheduling risk. Reference points from delivered work:
| Project | Size | Field days | Delivery |
|---|---|---|---|
| Hospital wing | 38,400 sq ft | 2 overnight shifts | federated Revit in 8 business days |
| Warehouse conversion | 96,400 sq ft | 2.5 days | LOD 300 Revit in 18 business days |
| Distribution center | 250,000 sq ft | 4 days | full deliverable by day 15 |
| Historic block | 180,000 sq ft | 6 days | Revit 2024 LOD 300 in three weeks |
Capture rate on open interiors runs 80,000–120,000 sq ft per day, so field duration is estimable up front. Modelling duration is where providers differ.
7. What formats do you actually get?
Insist on the native cloud alongside the model — E57 for the open archive, RCP for Revit linking, LAS or PTS where analysis tools need them. A model handed over without the cloud it came from cannot be verified later. See point cloud file formats for what each format carries.
8. Is there an acceptance test, and is it in the contract?
The test that protects both sides:
- 30 random dimension checks, model against cloud, ≥90% in tolerance
- 95% completeness of elements within scanned areas
- A named sample area reviewed before full modelling proceeds
- A live walkthrough within 5 business days of handoff
Contract language is in our scope of work template. If a provider resists an acceptance test, that is the answer to the evaluation.
9. What does it cost, and is the quote comparable?
Capture and registration alone runs $0.05–$0.20/sq ft. Scan-and-model all-in runs $0.25–$0.60/sq ft, depending heavily on LOD split and MEP scope. Two quotes are only comparable if the LOD split, the tolerance, the formats, and the acceptance criteria match. Most quote spreads that look dramatic are actually scope spreads.
10. Do they understand the structural question behind the scan?
The last criterion is not a checkbox. A provider who asks what the retrofit is doing, where the new load path goes, and which connections are being modified will scan the building differently than one who asks for a square footage. That conversation, at the proposal stage, predicts the deliverable better than any credential.
Structural teams sizing a retrofit can reach ZEALOT at 614-210-3679, or start with Scan to BIM and Building 3D Laser Scanning.