1. Definition and contractual force
A site instruction is a written document issued by the contract administrator to the contractor holding the contract. It is the formal act by which the administrator exercises the powers the conditions of contract delegate: starting the works, ordering changes, recording particular situations, applying sanctions.
Its contractual force rests on three cumulative conditions: it must be written, with no such thing as a verbal instruction; it must be issued by an authorised person, the contract administrator or a delegate with signing authority; and it must be notified to the contractor with proof of receipt. An instruction that fails any of the three is legally fragile, and the contractor can dispute its effect.
ℹ Instructions and site minutes: what is the difference? A formal instruction is a contractual act. It binds client and contractor, produces legal effects on time, damages and price, and has to be archived. Site minutes and meeting notes are not instructions: they record exchanges but do not produce the same contractual effects. A change ordered verbally in a site meeting and recorded in the minutes is not an instruction to vary; it triggers neither the contractual obligation to carry the change out nor the procedure for valuing it.
2. The six types and their contractual effects
| Type | Purpose | Issued by | Contractual effect | Example |
|---|---|---|---|---|
| Instruction to commence | Notifies the official start date and sets the contract period running | Contract administrator | Starts the contract period; without it there is no enforceable period | "We hereby instruct you to commence the works on the stated date." |
| Instruction to suspend | Temporarily suspends the works and stops the contract period | Contract administrator | The period is suspended; the contractor is compensated for the cost of maintaining the site where the suspension is the client's responsibility | Contamination discovered, a planning condition outstanding, prolonged bad weather |
| Instruction to resume | Ends the suspension and restarts the remaining period | Contract administrator | The period restarts from the date of the instruction; any challenge to that date must be made within 15 days (CCAG-Travaux 2021, art. 3.8.2: fifteen days from receipt of the instruction, on pain of being time-barred) | Follows a suspension; the date is critical |
| Instruction to vary | Orders a change to the works: additional work, omissions, technical changes | Contract administrator | Creates the obligation to carry out the change, is approved beforehand by the client and sets a provisional price; the variation, which settles the final price, may follow execution (CCAG-Travaux 2021, art. 3.8.1, 13.4 and 13.5) | A change to a partition layout, an additional opening, a change of material |
| Instruction recording a fact | Records a particular situation: a delay observed, defective work, a failure, absence of labour | Contract administrator | Constitutes evidence, and is the basis for liquidated damages or for snags at completion | Recording a 15-day delay against the programme, as the basis for calculating damages |
| Formal notice | A formal demand that the contractor remedy a breach within a stated time, before contractual sanctions apply | Contract administrator, with the client's agreement | Starts the grace period before sanctions, and before termination at the contractor's risk | A demand to resume abandoned works within eight working days |
The formal notice is the most serious of the six, since it precedes the heaviest sanctions: termination at the contractor's risk and calling the retention. It should never be issued without prior consultation with the client, and without checking that the intermediate steps, a written record, an informal demand, have actually been taken. Issuing one hastily can create a disproportionate dispute over a simple, one-off delay.
3. Drafting one properly
A well-drafted instruction is short, precise and factual. It describes the situation or the order without ambiguity, refers to the applicable contract condition, sets a time for reply and leaves space for the acknowledgement of receipt. The table below sets out the eight sections of a standard instruction with the reason for each.
| Section | Standard content | Why it matters |
|---|---|---|
| Header | Project, package and description, contractor, contract reference, date | Identifies the contract without ambiguity; an instruction with no contract reference is hard to enforce |
| Instruction number | Sequential numbering per package | Sequential numbering lets the full chronology be reconstructed in a dispute |
| Type | A short line naming the type of instruction | Characterises it legally and determines its contractual effects |
| Body | A precise, factual description of the change, the fact recorded or the order, with references to the contract conditions where applicable | The precision of the body determines enforceability; a vague record can be challenged |
| Contract reference | The applicable condition: time for reply, damages, how variations are valued | Anchors the instruction in the contract and forestalls any challenge to its legitimacy |
| Time for reply | "The contractor has a stated number of working days to notify its agreement or its reservations." | Without a stated period the instruction can go unanswered, and tacit agreement is rarely enforceable |
| Signature | Signature and stamp of the contract administrator, with the date of issue | It must be issued by an authorised person, not by a colleague with no delegated authority |
| Acknowledgement | A box for the contractor to sign and date on receipt | The acknowledgement proves notification; without it the effective date can be challenged |
A worked example: an instruction to vary
| Instruction 02-008, instruction to vary | ||||
|---|---|---|---|---|
| Project: eight dwellings | Package: 02, concrete frame | Contractor: [name] | Contract reference: [number] | Date: [date] |
| Subject: change to the position of the service openings at second floor level. | ||||
| Following the revised plumbing drawings issued by the services engineer, revision C, we instruct you to change the position of the structural openings at second floor level in accordance with the drawing attached. | ||||
| The change involves relocating six existing openings not yet cast and forming three additional ones. The provisional prices for this change, fixed after consulting your firm and with the client's agreement, are set out in the attached price build-up or breakdown. You have thirty days from notification of this instruction to submit your observations; failing that, these prices will be deemed accepted for the purposes of the accounts (CCAG-Travaux 2021, art. 13.4 and 13.5). This instruction has been approved beforehand by the client; the justification of that approval is attached (art. 3.8.1). | ||||
| Signature, contract administrator: ____________ | Date acknowledged: ____________ | Signature, contractor: ____________ |
4. Keeping the register
The register of instructions is the contractual dashboard of the site. It centralises every instruction issued, its status, the replies received and the variations that follow. Its absence or incompleteness is regularly cited in expert reports as an aggravating factor against the design team.
| Column | What goes in it | What it is used for |
|---|---|---|
| Number | Sequential per package, in the format package-number | Lets the chronology be reconstructed |
| Date of issue | The date the administrator signed | The starting point of the contractual periods |
| Type | Commence, suspend, resume, vary, record, formal notice | Allows filtering by nature |
| Subject | A one-line description | Quick navigation through the register |
| Date acknowledged | The date the contractor signed for it | Proof of notification, critical in a dispute |
| Reply due | The deadline for the contractor's reply | Allows chasing where no reply arrives in time |
| Reply and reservations | A summary of the reply or the reservations raised | Records the disagreements and prepares the final account |
| Related variation | The number of the variation arising, where there is one | A traceable link from instruction to variation to final account |
| Status | Open, reply received, closed, variation signed | The control dashboard for the site |
ℹ The recommended format A shared spreadsheet with one tab per package is the most practical format: it allows filtering by type, tracking the reply deadlines and identifying the instructions still outstanding. A summary tab across all packages gives the client an overall view. The recommended numbering is the package number followed by a sequential number, for example 02-008 for the eighth instruction on package 02. That convention makes traceability straightforward in the variations and in the final account.
5. From instruction to variation: the contractual chain
An instruction to vary triggers a four-step contractual chain that has to be respected if the change is to be valued properly at final account.
Step 1, the instruction: the administrator orders the change in writing, referring to the drawings or documents that justify it. The instruction states that the varied works will not be carried out until they have been valued by a variation.
Step 2, the contractor's price: the contractor prices the change within the time allowed. Its proposal must build up the price according to the contract rules: schedule rate, rate from the schedule of rates, or a new rate built up from net cost.
Step 3, negotiation and approval: the administrator analyses the proposal, negotiates where necessary, and submits the variation to the client for approval; the client has been involved since the instruction, which it approved before it was issued and whose provisional prices it accepted (CCAG-Travaux 2021, art. 3.8.1 and 13.4).
Step 4, signature: the variation signed by both parties makes the change contractual, updating the contract sum, the period where necessary, and the pricing schedule.
The commonest mistake is to short-circuit that chain: the contractor carries out the change with no price agreed beforehand, and tries to value it at final account. Without a variation signed in advance the price can be disputed. The administrator has to insist on the sequence: consultation of the contractor, an instruction approved by the client at provisional prices, execution, then a variation settling the final prices (or prices that have become final for want of observations from the contractor within thirty days).
6. Instructions and liquidated damages
Liquidated damages are among the most frequently mishandled mechanisms on site, either because they are not notified in time or because the preliminary procedure was never followed.
Condition 1, the instruction to commence must have been issued: without it the contract period does not run. Damages are calculated from the start date notified in the instruction, not from the date work actually began.
Condition 2, the delay must be recorded by instruction: damages have to be notified as they arise, by an instruction recording the fact. Applying them for the first time at final account with no such record can be challenged, since the contractor can argue it was never told of the delay in real time.
Condition 3, the excusing causes must be checked: delays attributable to the client, late changes, access refused, drawings late, cannot attract damages. Where a suspension was notified, the corresponding period is deducted.
ℹ Applying damages at final account with no prior record This is the commonest mistake of all. The contractor finishes three weeks late. The design team applies damages in the final account, but no instruction recording the delay was ever issued during the works. The contractor objects: it was never notified of the delay, had no opportunity to justify it, and could propose no corrective measures. On a public contract, the administrative courts decide that situation in the contractor's favour almost every time. On a private contract, the risk of litigation is high. The rule is to record delays by instruction as they happen, not at final account.
7. The eight classic mistakes
| Mistake | Consequence | Severity |
|---|---|---|
| No instruction to commence; the works simply start | The contract period never runs and damages cannot be applied | ★★★★★ |
| An instruction to vary with no prior variation | Work carried out with no contractual price, valuation disputed at final account | ★★★★★ |
| No instruction recording an observed delay | Damages must be notified in real time; applying them at final account will be challenged | ★★★★ |
| An instruction signed by a colleague with no delegated authority | The contractor can challenge it; check the delegation in the conditions of contract | ★★★ |
| Acknowledgement of receipt never collected | The date of notification can be challenged and the contractor can deny receipt | ★★★★ |
| No register, or an incomplete one | The chronology cannot be reconstructed in a dispute, weakening the position at final account | ★★★★ |
| A formal notice issued with no prior demand | A formal notice has to follow a demand; its absence weakens any termination procedure | ★★★ |
| The contractor's reply never archived | Reservations on an instruction are a contractual disagreement; losing them creates a grey zone | ★★★★ |
In summary
The site instruction is the formal contractual act by which the design team exercises its powers on site. It comes in six types with distinct effects: commence, suspend, resume, vary, record, formal notice. A valid instruction is written, signed by an authorised person and notified with an acknowledgement of receipt. The register is the contractual dashboard of the site, and its incompleteness systematically weakens the design team's position. The chain from instruction to price to variation to execution must never be short-circuited. Liquidated damages have to be notified by instruction as the delay arises, not at final account. The two most serious mistakes are no instruction to commence, which makes the contract period unenforceable, and an instruction to vary with no prior variation, which leaves the valuation open to dispute.