1. Variations: legitimate, questionable and abusive
A variation is a modification of the original works contract: additional work, a change of quantity, a technical adaptation. Not all variations are equal: some are perfectly legitimate, others contestable, others purely abusive. The ability to distinguish the three in real time is one of the economist's most valuable competences during construction.
| Type of variation | Legitimacy | Indicative order of magnitude | Concrete example | Response |
|---|---|---|---|---|
| A genuine unforeseen condition in ground or services | ✔ Legitimate | 3 – 15 k€ | A pocket of made ground undetected in the survey, foundations deepened | Check against the ground survey and record it jointly |
| A client change of brief | ✔ Legitimate | Variable | The client asks mid-site for an additional partition | A change note signed by the client before the work |
| A partial quantity error in the tender documents | ⚠️ Questionable | 2 – 10 k€ | The contractor under-estimated the linear metres of a service run | Check against the drawings; if the error comes from the tender documents: at a lump-sum price, for a contract that refers to the CCAG-Travaux 2021, a quantity error in the breakdown does not alter the price (art. 10.3.1), and an appeal court has allowed the contractor to pursue the liability of the design team that drew it up; at unit prices, the quantities carried out are paid at the contract prices (art. 10.3.2); on a private contract, according to what the contract says about the pricing schedule |
| Work already included in the contract | ✘ Abusive | 5 – 50 k€ | The contractor claims as a variation work described in its own specification | Refuse, citing the signed specification |
| Work done in time but claimed later | ⚠️ Questionable | Variable | Work carried out but the claim filed three months later to negotiate | Check the execution programme and the site records |
| A low bid recovered through variations | ✘ Abusive | 20 – 100 k€ | A contractor that under-bid at award accumulates variations on site | Rigorous tender analysis upstream, and watch the warning signals |
| Delay caused by client or design team | ✔ Legitimate | 5 – 30 k€ | Drawings delivered late; the contractor claims mobilisation costs | Analyse the contractual programme: whose responsibility? |
| Price adjustment under a contract clause | Not a variation | According to the contract's formula and indices | On public contracts, updating of a firm price if more than three months separate the offer from the start of performance, revision of a revisable price according to the contract's formula, whatever the length of the site; on private contracts, as the contract provides | Check the index calculation; it is often done wrong |
Price adjustment does not go through a variation, except, in a contract that refers to the CCAG-Travaux 2021 without setting an updating index, the setting of the updating coefficient (art. 9.4.3): it applies under the contract clause and is tracked on a separate line of the dashboard. As an indicative order of magnitude, with no published statistic behind it: on a properly run construction project, legitimate variations represent 3 to 6 % of the contract sums. Above 8 %, the signal is clear, either the tender documents were incomplete, or abusive variations have been accepted without control. On projects where a low bid went undetected at award, the rate climbs to 15 to 25 %.
ℹ The rule of three questions Faced with any variation request, the economist asks three questions in this order. First: was the work described in the specification or on the drawings? If yes, the variation is abusive, the work is already due under the contract. Second: does the work result from an unforeseen condition that could not have been stated at tender? If yes, the variation is legitimate, but the amount must be justified by a quantified breakdown and coherent unit rates. Third: does the work result from a change decided by the client or the design team after the contract was signed? If yes, the variation is legitimate, and the amount must be negotiated on the basis of the contract's schedule of rates.
2. The monthly financial dashboard
The site financial dashboard is the document that reconciles in real time the original contract sums, the variations approved, the variations under assessment and the remaining provision. Without it, the client discovers the overrun at handover, when no lever of action remains.
Its minimum structure has five columns per package: the original contract sum, cumulative approved variations, the total committed, the initial variations provision, and the balance of that provision. A negative balance is an immediate warning that should trigger a budget steering meeting with the client.
The recommended update frequency is monthly, aligned with the interim valuations contractors submit for payment. Each valuation is an occasion to check that the quantities carried out correspond to the drawings and to the progress observed on site.
ℹ The silent month is the most dangerous The largest slippages happen in periods when financial monitoring has been neglected: the summer break, a change of economist mid-appointment, a period of heavy activity on other projects. Fictitious example: one month without an updated dashboard on a 3 M€ site with 12 contractors can let 50 to 100 k€ of unassessed variations through. Three months of neglect can generate a financial position impossible to correct without open conflict with the contractors.
3. Delay: an often under-estimated financial risk
Delay carries direct and indirect financial costs often under-estimated in initial budgets. The direct cost is the most visible: keeping the site open longer, with crane and welfare hire and security; extending the design team's supervision; additional finance costs. The indirect cost is more insidious: rent or trading income not received as planned, late delivery penalties towards buyers or tenants, and the prolonged mobilisation of the client's own teams.
Contractual protection works through two instruments: delay damages in the administrative conditions, and a detailed contractual programme annexed to the contract. A detailed programme by task, with intermediate milestones, is the indispensable basis for qualifying a delay and calculating the damages due.
The reality on site is that delay damages are rarely applied in full: the working relationship between client and contractor usually involves negotiation. But their existence in the contract is a lever that speeds up decisions and holds contractors to their programme.
4. The timeline of a contractor dispute
When a disagreement cannot be settled amicably, it enters a formalised procedure whose every step carries a deadline and precise obligations. Knowing that timeline allows deadlines to be met and the file to be built correctly at each stage.
| Step | Timing | Client's action | Design team's action | Risk of inaction |
|---|---|---|---|---|
| The contractor files its claim | Handover + 3 months | Acknowledge formally, by recorded delivery | Analyse the claim item by item | Client silent for thirty days: the claim is rejected (CCAG-Travaux 2021, art. 55.1.2 and 55.1.3) |
| The client replies | Day 45 to 60 | Accept, contest or negotiate in part | Produce a priced counter-statement | Final statement not contested in time deemed accepted, except additional work under a lump sum that the client neither authorised nor regularised (private contract that refers to NF P 03-001) |
| Attempt at amicable settlement | Day 60 to 120 | A conciliation meeting, propose an agreement | Price the acceptable fallback positions | Without agreement, a long and costly judicial procedure |
| Mediation or arbitration | Day 120 to 180 | Appoint a mediator or an arbitrator | Build the technical and economic file | Often less costly than the courts |
| Judicial expert determination | Day 180 to 540 | Apply to the court and seek an expert | Assist the expert, supply the documents | A long process; legal and expert fees to provide for |
| Judgment | Day 540 to 1,080 | Wait, or negotiate an agreement meanwhile | Technical testimony if required | Two to five years, 30 to 100 k€ of costs |
| A final account signed amicably | Ideally day 90 | Sign before any litigation | Reconcile the accounts, produce the account | Without it, the contract balance stays contestable |
The golden rule is simple: a final account signed amicably within 90 days of handover is always preferable to any judicial procedure. Litigation on a 3 M€ site can cost 50 to 150 k€ in legal, expert and procedural fees, for an uncertain result over two to five years. Negotiating a final account, even conceding 30 to 50 k€, is almost always economically superior.
5. The final account: the most poorly handled document in construction
The final account is the document that definitively settles the contract between client and contractor. It brings together all the work carried out, every approved variation, any damages and the price revisions. Its signature closes the contractual relationship.
Yet the final account is systematically the most neglected document in French construction. The reasons are several: the procedure is complex and the deadlines short, economists have often moved to other work, and clients regard handover as the real end of the site. That neglect generates costly disputes that could have been avoided. The periods in the checklist below apply to a public contract that refers to the CCAG-Travaux 2021 without departing from it; on a private contract, they are those of the contract.
| Control point | Responsible | Statutory period | Risk if missed |
|---|---|---|---|
| The contractor's draft final statement | Contractor | 30 days from notification of the handover decision (CCAG-Travaux 2021, art. 12.3.2) | Without it, the client draws its own account, at risk of challenge |
| The draft final account by the design team | Economist and design team | 30 days after receiving the statement | Delay risks tacit acceptance of the contractor's statement |
| Notification of the account to the contractor | Client | 30 days after the final payment request is received by the design team or by the client, whichever is later (CCAG-Travaux 2021, art. 12.4.2) | Without formal notification, deadlines and remedies are uncertain |
| The contractor's period to contest | Contractor | 30 days after notification | Beyond it, the account is final and incontestable |
| Reconciling the variations, an exhaustive signed list | Economist and design team | Before signature | An unreconciled variation is a potential dispute after signature |
| Delay damages calculated and deducted | Economist and design team | Before signature | Damages not applied are definitively abandoned |
| Price revision calculated on the official indices | Economist | Before signature | Index calculation errors are frequent and can cost 20–50 k€ |
| Retention of 5 %, released or replaced by a guarantee | Client | Within thirty days of the end of the guarantee period, or of the clearing of snags still outstanding at that date (R2191-35) | Retention not released becomes a dispute |
| Handover defects cleared, on a joint list | Design team and client | Through the defects period | Defects not cleared block the final account |
| Joint signature of the final account | Client and contractor | End of the defects period | Unsigned, the contract balance stays indefinitely contestable |
ℹ The tacit account: the most expensive trap On a private contract that refers, for closing the accounts, to the procedure of standard NF P 03-001, a client who does not contest the contractor's final statement within the time allowed may be deemed to have accepted it. That acceptance does not extend to additional work under a lump-sum contract that the client neither authorised nor regularised: for that work, the Cour de cassation requires a written agreement and an agreed price given beforehand or, failing that, an express and unequivocal acceptance of the works once carried out, and holds that neither silence on the final statement nor failure to follow the account-closing procedure takes its place. If a contractor files a claim for 80 k€ of contestable variations, the client therefore replies in writing, item by item and within the periods of the contract: its silence would not make those additional sums due, but it could cause the other claims in the statement to be deemed accepted. The absolute rule: every claim or draft final statement received from a contractor must generate a formal written reply within the contractual period, even to contest, even to ask for more time to assess.
6. Handover: the first act of a potential dispute
Handover is a major legal act: the moment custody of the works passes from contractor to client. It starts several statutory periods: the one-year defects liability, the two-year warranty on equipment and the ten-year structural liability.
The list of defects at handover is a strategic document. Defects too numerous and badly worded are hard to track and to clear. Too few can leave damage uncovered. Good practice is a precise, located list with a clear criterion for clearing each item and a period defined by type.
- Structural defects: damage affecting the structure or the weathering, to be treated as an absolute priority before anything else is cleared.
- Finishing defects: defects in the finishing trades, to be cleared within 30 to 60 days of handover.
- Compliance defects: non-conformities against the drawings and the specification, to be cleared with supporting documentation.
In summary
Site risks concentrate on three fronts. Variations, legitimate at 3 to 6 % and a warning beyond: distinguish legitimate, questionable and abusive with the rule of three questions. Disputes, whose timeline runs from day zero to day 1,080: a final account signed amicably within 90 days always costs less than litigation. And the final account, the most neglected and most dangerous document, which a ten-point checklist secures against tacit acceptance. The monthly financial dashboard is the central steering tool: one month of neglect on a 3 M€ site can let 50 to 100 k€ of unassessed variations through.
The nature of the figures quoted
The percentages and amounts quoted on this page are orders of magnitude for framing, not measurements. They illustrate mechanisms and proportions, and they substitute neither for a tender exercise nor for an estimate prepared on drawings.
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Sources: the BT construction cost indices published monthly by INSEE on its 2010 base, used to update the figures · construction cost statistics from SDES, the statistical service of the ministry responsible for construction · regulatory texts published in the Journal officiel and consolidated on Légifrance for the requirements cited.