How to verify construction progress before you pay
Andrés Segnini Capriles8 min read
Illustrative example of an evidence item’s journey. Demo data.
Paying for progress instead of by the calendar is the fairest way to fund a construction project, on one condition that is almost never met: progress has to be provable beyond argument. As long as the proof is a stray photo in a chat or one party’s word, every progress certificate is a negotiation.
What you verify when you verify a milestone
You don’t verify “the project”. You verify a specific milestone, and a well-defined milestone answers three questions at once:
- What: the part of the work committed to, tied to the budget line items paid for by that tranche.
- How much: the measurement of what has been built against what was planned. It is the basis of the amount.
- How well: that the work complies, not just that it exists. A structure built with a visible defect is not a completed milestone.
If the milestone isn’t written this way before work starts, no later verification can fix it: there is nothing to compare against. That is why verification starts in the contract, not on the site visit.
The usual ways to check it, and where they fall short
| Method | What it brings | Where it falls short |
|---|---|---|
| Site visit by the technical supervisors | Technical judgment and professional responsibility | Visits are spaced out, and each one holds back payment until it happens |
| Photos over messaging apps | Speed; anyone can take them | They don’t prove when or where they were taken; they get forwarded, cropped and lost in the chat |
| The contractor’s own report | Detail of the work done | It is signed by the party being paid: the client is, by definition, inclined to distrust it |
| Drone or scanner survey | Geometric precision | Cost and logistics that only pay off on large projects or very specific milestones |
None of them is bad. The problem is that each one solves one part and all of them leave the same gap: between someone seeing the work and someone paying for it, the proof passes through hands that can alter it or dispute it.
What turns a photo into evidence
A photo proves nothing on its own. It becomes evidence when it carries four pieces of data that nobody can change afterwards:
- When. A timestamp that fixes the moment the photo is recorded, not the date someone types into a report.
- Where. The device’s GPS position when the photo is taken with the camera on site. A stock image or a photo from another project no longer slips through.
- That it hasn’t been touched. A cryptographic hash: a 64-character code calculated from the exact file. Change a single pixel and the code changes.
- Which milestone it belongs to. The evidence is uploaded against a milestone in the contract, not to a generic folder. That way everyone knows what it is trying to prove.
The argument is no longer whether the photo is good, but whether what it shows meets what the milestone required.
With those four pieces of data the conversation changes: it becomes a technical discussion, and a technical discussion can be closed.
Two reviews, never one
Once the evidence is reliable, someone has to judge it. In the Cimbrium ecosystem, with PactStream (switching on with our first clients), that will be done by two independent reviews of the same evidence, and no release of funds will depend on just one:
The AI analysis reviews the evidence before anyone else and issues an assessment: a score from 0 to 100, a verdict (no objections, review or blocking) and a list of findings ranked by severity, each one pointing to the file it refers to. An ambiguous photo, an invoice that doesn’t match the line item or a missing piece of evidence shows up there, before it reaches anyone’s desk.
The technical supervisor certifies on that same evidence, with the assessment in front of them. It doesn’t replace their judgment or their responsibility: it organizes them. Instead of going through fifty photos with no context, they review proof that has already been sorted and focus on what the AI flagged.
AI alone would be fast but wouldn’t have the professional competence to sign off on construction work. The technical supervisor alone keeps the same old bottleneck. Together, the judgment stays human and the time stops being the problem.
What happens when verification doesn’t add up
This is where you see whether the system protects both parties or only one. If the assessment or the technical supervisor doesn’t validate the milestone, the amount neither goes back to the client nor gets lost: it stays held in the escrow account. The contractor sees which findings are blocking it, provides the missing evidence or fixes what wasn’t compliant, and the milestone is reviewed again.
The client knows their money isn’t released without proof. The contractor knows the money exists and only depends on demonstrating progress. Neither has to rely on the other’s cash flow or good faith.
Checklist for your next progress certificate
Whether or not you use a platform, these six questions prevent most disputes:
- Is the milestone defined in the contract, with its amount and its completion condition?
- Is it clear what evidence is needed to consider it complete: photos, measurements, delivery notes, tests?
- Are photos taken on site and recorded on the spot, without going through a chat or the phone’s editor?
- Is each piece of evidence linked to the milestone it is meant to prove?
- Who certifies, and within what time frame, and is it written down before work starts?
- Where is the money in the meantime, and who decides to release it?
The last question is the one most often forgotten and the one that matters most. Flawless verification is of little use if payment then depends on whether the other party has cash that month.
What sits behind verified progress
| Division | What it brings here |
|---|---|
| CostPact | The budget, built on an official price catalog, that defines each milestone and its amount, and the project management that produces the measurement and the draft progress certificate. |
| PactStream | Evidence recording, AI analysis, certification by the technical supervisor and safekeeping of the amount in an escrow account until it is released. Built and switching on with our first clients, with custody through a regulated payment provider. |
| FiscalCore | The released payment, split on arrival into taxes, costs and profit, with Spain’s quarterly tax forms 303, 111 and 130 calculated in real time. |
| PropertyJourney | When the project is a real estate development, the sales that start it and the handover and after-sales that close it. |
Frequently asked questions
Does AI replace the technical supervisors?
No. The technical supervisors (in Spain, the dirección facultativa) have the competence and the responsibility to sign off on completed work. The AI reviews the evidence before they do and points out what doesn’t add up, so that certification is based on organized proof rather than a folder of photos.
Are photos taken with a phone good enough?
Yes, if they are recorded on the spot and unedited. What makes a photo valuable isn’t the camera, but being able to prove when and where it was taken, which milestone it belongs to and that nobody has modified it since.
What is a file’s cryptographic hash?
A 64-character code calculated from the exact content of the file. Change a single pixel of the photo and the resulting code is different, so any later alteration is exposed.
What happens if the client disagrees with the progress?
The milestone amount stays held in the escrow account until it is resolved. The findings show what is missing or what doesn’t match, and the discussion focuses on that specific evidence instead of on conflicting versions.
