Civils.ai vs. Structured AI: Geotechnical Takeoff vs. Automated Revit/AutoCAD QA/QC Drawing Redlines

01The short answer: buy by task, not by brand

Civils.ai and Structured AI are often grouped together as AI for civil and AEC firms, but they target different work. Based on published descriptions:

• Civils.ai focuses on reading geotechnical documents, digitizing borehole logs and producing civil quantity takeoffs for earthworks and concrete. Reported plans are $90 a month (Starter, 10 takeoffs), $270 a month (Pro, 30 takeoffs) and an Enterprise tier with API access and single sign-on.
• Structured AI focuses on automated QA/QC of drawing sets, marking up issues across Revit, AutoCAD and Civil 3D. Reported pricing is about $30 per seat per month for each tool, with enterprise drawing-set compliance audits offered separately.

A geotechnical or site civil firm doing many takeoffs will look first at the first tool. A multidiscipline AEC firm that issues many drawing sets will look first at the second. Some firms need both. Engineer Aid is independent of both vendors; confirm current plans before you buy.

Either way, the output is a draft for an engineer to check. Under the NCEES Model Law and state board rules, the licensed engineer who seals the drawings must have the work under responsible charge, whatever software produced the first pass.

02Side-by-side: what each tool does and how it is priced

Treat the table as a list of things to confirm in a trial.

The pricing units point to different buying decisions. A takeoff plan is a volume bet: you commit to a monthly number of tasks, and the risk is unused capacity in slow months. A per-seat, per-tool plan is a headcount bet: the risk is licensing people who rarely run checks, or paying for a tool your firm uses on only a few projects. Ask both vendors for the last three months of usage reports during a trial, so you size the plan from real activity rather than from the sales estimate.

03Civils.ai plan economics: the cost per takeoff

Volume plans are cheap per unit only when you use them. Divide the monthly price by the takeoffs you actually run.

Two buying rules follow. First, size the plan to your quiet months, not your busy ones, if overage or a temporary upgrade is available; ask how extra takeoffs are priced. Second, the subscription is a small part of the cost. Even at $18 a takeoff, the engineer time to check the output matters far more, as the next section shows. At 20 takeoffs a month on Pro, a year costs $3,240.

04Worked example: takeoff time saved

Assumptions to replace with your own pilot data: a manual geotechnical log and quantity takeoff takes 6 hours of engineer time at a $90 burdened rate, so $540. With AI, the engineer spends 1.5 hours checking and correcting the output, $135, plus the $9 plan cost per takeoff. Total $144.

• Saving per takeoff: $540 - $144 = $396.
• At 20 takeoffs a month: 20 x 12 x $396 = $95,040 a year of engineer time, against a $3,240 plan.

The number that decides the result is review time. If checking takes 4 hours instead of 1.5, the AI takeoff costs $369 and the saving falls to $171 a takeoff, still positive but less than half. If checking takes 6 hours because the output cannot be trusted, there is no saving at all. Measure review time on ten of your own past projects, using their original manual takeoffs as the answer key, before you commit to a yearly plan.

Also check how the tool handles your log formats. Ground investigation reports from different drilling contractors use different layouts, and accuracy on one format says little about another.

05Structured AI seat economics: QA hours per drawing set

Seat pricing per tool means cost grows with both headcount and the number of platforms you check. A firm with 15 production staff using two of the supported tools pays 15 x 2 x $30 x 12 = $10,800 a year.

The margin here is thinner than for takeoffs, so seat count matters. If only five QA reviewers actually run checks, license five, not fifteen: the cost drops to $3,600 and the net rises to $12,600. The value of catching errors before issue, such as fewer requests for information and less site rework, is real but hard to measure; track it, but do not count it in the buy decision until you have data.

06Responsible charge, seals and liability

Every state engineering board, guided by the NCEES Model Law, prohibits a PE from sealing work not prepared under their responsible charge or independently verified by them. AI-generated takeoffs and AI redlines are inputs to that check, not a substitute for it. Practical rules for firms using these tools:

• Keep the engineer's own check visible: who reviewed the AI output, what they changed, and when.
• Retain calculations and review records for the period your state board and contracts require, commonly 3 to 10 years.
• Do not describe AI QA as a completed quality check in client deliverables.
• Ask your professional liability insurer whether AI tool use needs to be disclosed.
• In SE-mandatory states such as Illinois, the structural engineer of record still owns the structural check.

The structural and civil A&E seal risk playbook covers responsible charge in more detail.

07Data handling and contract checks

AEC drawings and ground investigation reports often belong to the client, not the firm. Before uploading them to any AI service, check your client contract for confidentiality and data-location terms, and check the vendor's terms for:

1. Retention. How long uploaded drawings and reports are kept, and how they are deleted.
2. Training use. Whether your files are used to train models, and how to opt out in writing.
3. Security reports. Whether a SOC 2 Type II or equivalent report is available.
4. Single sign-on and user removal. Enterprise plans commonly add SSO; without it, departed staff may keep access.
5. Price changes. A fixed price for the term and a cap on renewal increases.

For a clause-by-clause review of both vendors' plans, see the Civils.ai and Structured AI pricing audit.

08Pilot plan for an AEC firm

Run each tool on past work where you already know the right answer:

1. Pick ten completed takeoffs or five issued drawing sets with known errors.
2. Run them through the tool and time the engineer's review.
3. Score accuracy: quantities within your tolerance, real issues found, false alarms raised.
4. Compute cost per task with the formulas above.
5. Buy the smallest plan or seat count that covers the users who cleared breakeven.

Score the security side with the AI copilot ROI and security scorecard. Firms that also want to cut Autodesk seat costs should read Autodesk named user vs. Flex tokens.

Keep the pilot honest by having someone other than the tool's champion score the results. Record the cases where the tool was wrong as carefully as the cases where it saved time, because those are the ones a reviewer must catch on live work.

09Run the numbers: aI CAD and engineering copilot ROI and ITAR / IP security scorecard

The same benchmarks as this sheet, with your inputs. Share link and printable brief open the full calculator page.