A WhatsApp message is written, it can be read, copied and recorded, and it is timestamped, so it is not automatically worthless under a construction contract. But NEC4, JCT and FIDIC each add rules about who can instruct, how communications must be sent and how notices must be identified. An instruction or notice that only exists in a site group chat usually breaks at least one of them. It can still prove what was said and when, which matters because the same message can start a notice clock.
Who this is for: commercial managers, quantity surveyors and site managers at contractors and subcontractors who receive instructions in site group chats, by phone or in passing, and want to know when those instructions count and how to protect the entitlement behind them.
The short answer, by contract
| Contract | Rules that matter | Is a WhatsApp instruction likely to be valid? | What to do |
|---|---|---|---|
| NEC4 ECC | 13.1 form, 13.2 communication system or address, 13.7 separate notifications, 14.3 only the Project Manager instructs changes | Doubtful, especially where the Scope names a communication system | Ask the Project Manager to issue it through the contract's system, and notify the compensation event separately |
| JCT 2016 (SBC, DB) | 1.7 service of notices and communications; SBC 3.12 and DB 3.7 confirmation of instructions not in writing | Uncertain; safest to treat it as an instruction not in writing | Confirm it in writing within 7 days |
| FIDIC 2017 | 1.3 paper or electronic original from the system in the Contract Data, Notices identified as Notices; 3.5 instructions | Very unlikely: WhatsApp is rarely the stated system | Ask for a written instruction, and give a Notice before starting if you think it's a Variation |
NEC4: who sent it, and how
Clause 13.1 requires every communication the contract asks for to be in a form that can be read, copied and recorded. A spoken instruction fails that test. A WhatsApp message arguably passes it.
The problem is clause 13.2. If the Scope names a communication system, a communication takes effect when it is sent through that system. If it doesn't, it takes effect when received at the address the recipient last notified, or the one in the Contract Data. A personal mobile number is rarely either. The Civil Engineering Contractors Association's guidance goes further: where the Scope names a system, even emails are not a valid form of communication.
Authority is the next hurdle. Only the Project Manager can instruct a change to the Scope (clause 14.3), unless they have delegated that action. A site supervisor or the client's construction manager posting "go ahead and add the extra bay" has not given an instruction under the contract.
Clause 13.7 then requires notifications to be communicated separately from other communications, which NEC explains is "to avoid important things being overlooked". A compensation event notification buried in a chat thread invites a challenge.
When the Project Manager does instruct a change to the Scope, that is a compensation event under clause 60.1(1), and the Project Manager must notify it straight after giving the instruction, as a separate communication (clause 61.1). If they don't, the Contractor notifies under clause 61.3. The eight-week bar doesn't apply to events that arise from the Project Manager's own instruction, but relying on that exception means first winning the argument that a valid instruction was given. Our guide to the NEC4 eight-week notice clock covers the timing in detail.
JCT: confirm within 7 days
JCT clause 1.7 governs how notices and other communications are served. Most can be served by "any effective means" to the address in the Contract Particulars (1.7.3). Some, such as several of the termination notices, must follow stricter delivery rules (1.7.4).
For instructions that don't arrive properly in writing, the 2016 editions set out a confirmation procedure: SBC clause 3.12 (Architect/Contract Administrator) and DB clause 3.7 (Employer).
- The instruction has no immediate effect.
- The contractor confirms it in writing within 7 days.
- If the other side doesn't dissent within 7 days of receiving that confirmation, the instruction takes effect when that period ends.
Whether a WhatsApp message counts as a validly served written instruction depends on your notices clause and Contract Particulars, and the 2024 editions now expressly allow service by email to the addresses given there. The safe course in either edition is to treat a chat instruction as one that needs confirming, and to confirm it formally.
FIDIC 2017: notices and instructions
Sub-Clause 1.3 of the 2017 Red Book requires notices and all other communications, including instructions, to be in writing. Each must be either a signed paper original or an electronic original sent through the system of electronic transmission stated in the Contract Data, from the electronic address uniquely assigned to the sender. A Notice must be identified as a Notice.
WhatsApp is rarely the stated system, so an instruction or Notice sent that way is very unlikely to comply. The 2017 edition also dropped the 1999 edition's procedure for confirming oral instructions (under the 1999 Sub-Clause 3.3, the contractor confirmed within two working days).
Sub-Clause 3.5 adds a trap. If you think an instruction is a Variation but it isn't stated as one, you must give a Notice to the Engineer immediately, before starting the work. For how strictly the 28-day claim notice is applied, see our guide to the FIDIC 28-day time bar.
What the courts have said
We haven't found a reported UK judgment deciding whether a WhatsApp message is a valid notice under NEC4, JCT or FIDIC. The cases that do exist point both ways.
The closest construction case is about forming a contract rather than giving notice. In Jaevee Homes Ltd v Fincham [2025] EWHC 942 (TCC), the court held that an exchange of WhatsApp messages, "whilst informal, evidenced and constituted a concluded contract" (para 81). The same messages then worked against the subcontractor: "monthly applications" meant one application for payment a month, so an invoice sent as a second application in the same month was invalid (paras 107 and 144 to 146).
How a notice is sent can matter as much as what it says. An emailed notice in Greenclose Ltd v National Westminster Bank plc [2014] EWHC 1156 (Ch) "was ineffective; it was sent by a method that was not permitted, to an address that was not specified" (para 155). That was a banking dispute, but the point carries over to any contract that prescribes how notices are given.
Content counts too. In Obrascon Huarte Lain SA v HM Attorney General for Gibraltar [2014] EWHC 1028 (TCC), a progress report saying rain had affected the works was "clearly nowhere near a notice" (para 315).
The courts read notices through the eyes of a reasonable recipient: a notice must meet the contract's requirements in substance and form, be intended as a notice, and be free from ambiguity (Advance JV v Enisca Ltd [2022] EWHC 1152 (TCC), para 47). A one-line chat message rarely does all of that.
Turning a chat instruction into a protected entitlement
- Check who sent it. Under NEC4, only the Project Manager (or someone they've delegated to) can instruct a change. Under FIDIC, the Engineer or their delegate. Under JCT, the Architect/Contract Administrator or the Employer.
- Confirm it the same day, through the contract's channel. Under JCT you have 7 days; don't use them all. Under NEC4, ask the Project Manager to issue the instruction through the communication system. Under FIDIC 2017, ask for a written instruction from the Engineer.
- Notify the entitlement separately. A confirmation of an instruction is not a compensation event notification, a Notice of Claim or a loss and expense notification. Each has its own clause and its own clock. For JCT, see our guide to the JCT loss and expense notice.
- Keep the original message. Export the chat or save the message with its timestamp. It is your evidence of what was instructed and when you became aware of it.
- Don't reply "noted" and move on. A thumbs-up in the group chat doesn't protect anything on its own.
A short confirmation of instruction
Confirmation of instruction received by [WhatsApp / telephone / in person]
Project: [name]. Contract: [NEC4 ECC / JCT SBC or DB / FIDIC 2017], as amended.
On [date] at [time], [name and role] instructed us by [WhatsApp message / telephone call / in person] to [describe the instruction]. A copy of the message is attached.
We confirm the instruction under clause [JCT 3.12 / 3.7], or ask that it is issued through the contract's communication system [NEC4 13.2 / FIDIC 1.3]. Any compensation event, Variation or loss and expense notice will follow separately under the relevant clause.
Where OnNotice fits
Instructions like these often go unconfirmed because nobody outside the chat sees them in time. OnNotice can be added to a project's site group chat, with consent recorded before any messages are captured. It reads each message as it arrives, flags instructions and events that may carry an entitlement, cites the governing clause, and starts the clock from the day the event surfaced. Every flag links back to the original message in a tamper-evident record. It drafts the notice; a person decides what gets sent. See how it works.
For the wider picture across NEC4, FIDIC and JCT, see why contractors lose entitlements to time-bars.
Sources
- Jaevee Homes Ltd v Fincham [2025] EWHC 942 (TCC), judgment, paras 81, 107, 144 to 146
- Greenclose Ltd v National Westminster Bank plc [2014] EWHC 1156 (Ch), judgment, para 155
- Obrascon Huarte Lain SA v HM Attorney General for Gibraltar [2014] EWHC 1028 (TCC), judgment, para 315
- Advance JV v Enisca Ltd [2022] EWHC 1152 (TCC), judgment, para 47
- PBC Today, The importance of maintaining good communications in NEC contracts, quoting NEC4 clause 13.2
- NEC, Links between key NEC processes, on clauses 60.1(1), 61.1 and 13.7
- CECA, NEC4 Bulletin No. 24: Communication Flow (December 2022), on clauses 13.1, 13.2, 13.7 and 14.3
- NEC, Understanding the purposes of notifications in NEC4 contracts, on clause 13.7
- JCT, The JCT Design and Build Contract 2024 Edition: a year on, on clause 1.7 and email service
- Ramskill Martin, How to successfully claim and manage change under JCT, on SBC clause 3.12
- Institute of Construction Claims Practitioners, Notices under the FIDIC 2017 editions, on Sub-Clause 1.3 (written about the Silver Book)
This is general information about how NEC4, JCT and FIDIC typically treat instructions and notices, not legal advice for your contract. Communication rules are often changed by the Scope, Contract Particulars, Contract Data or amendments, so have a contracts specialist confirm the position on your project.
Frequently asked questions
- Is a WhatsApp message a valid notice under NEC4?
- Rarely on its own. NEC4 clause 13.1 only requires a form that can be read, copied and recorded, which a WhatsApp message is. But clause 13.2 makes a communication take effect through the communication system named in the Scope, or at the address last notified, and clause 13.7 requires notifications to be sent separately from other communications. A message in a site group chat usually fails one of those tests, so send the notice through the contract's own channel.
- Can a WhatsApp chat form a binding construction contract?
- Yes. In Jaevee Homes Ltd v Fincham [2025] EWHC 942 (TCC), the court held that an exchange of WhatsApp messages, although informal, formed a concluded demolition subcontract. The same messages then shaped the payment terms: the words 'monthly applications' limited the subcontractor to one application for payment each month.
- How long do I have to confirm an oral instruction under JCT?
- Under JCT 2016, an instruction given other than in writing has no immediate effect. The contractor confirms it in writing within 7 days, and it takes effect if the Architect/Contract Administrator (SBC clause 3.12) or the Employer (DB clause 3.7) doesn't dissent within 7 days of receiving the confirmation.
- Does a WhatsApp message start the NEC4 eight-week clock?
- It can be evidence that it did. Clause 61.3 runs from when the Contractor became aware of the event, and a message in the site group chat shows exactly when someone on the Contractor's team knew. That is why an informal message can start the clock without counting as the notification itself.