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Commencement of Works — Deep-Dive on Clause 30.1 (NEC3 vs NEC4) 🚧

1️⃣ Purpose of Clause 30.1 — what is it really doing?

Think of Clause 30.1 as the “site gatekeeper.” It sets two non-negotiables:

No physical work on the Site until the first access date.
Do the works so that Completion lands on or before the Completion Date.
This is true in both NEC3 and NEC4 (the wording is almost identical).

Why does this matter?

Risk control: It prevents premature on-Site activities (and the preliminaries burn that comes with them) if the Client/Employer hasn’t provided access. If access is late against the contract, that is a compensation event.
Program discipline: Commencement isn’t just a date you “pick.” It’s coordinated through the Accepted Programme, which must visibly show starting date, access dates, Key Dates, and Completion Date.

A quick history note (NEC3 ➜ NEC4): the rule itself didn’t change. NEC4 cleans up language (“Employer” ➜ “Client”, “Works Information” ➜ “Scope”), and it tightens some surrounding processes (e.g., the PM’s follow-on instruction when stopping work under 34.1), but your commencement trigger—first access date—stays the same.

Bonus timing anchors you’ll live by: the PM certifies Completion within one week of the date of Completion (NEC3 & NEC4). That cadence matters for end-game milestones, but it also frames how disciplined the contract is with time events.

2️⃣ Breakdown of Clause 30.1 and its closest “wingmen” (31, 32, 33, 34, 60)

Let’s map the commencement ecosystem. Clause 30.1 sits at the centre, surrounded by five clauses that make it work in practice.

A) The commencement gate — Clause 30.1

Rule: Do not start work on the Site before the first access date; deliver the works so that Completion lands on/before the Completion Date. NEC3 and NEC4 mirror one another.

B) The control tower — Clause 31.2 (The Programme)

Your programme must show the starting date, access dates, Key Dates, Completion Date, planned Completion, logical sequence, and interfaces (Client/Others). It must also show when you’ll need later-than-access-date access, acceptances, Client-provided items, and information from Others. That is how you operationalise commencement. (NEC3 & NEC4.)

C) Access obligation — Clause 33.1

The Employer/Client must allow access to each part of the Site on or before the later of (i) its access date and (ii) the date for access shown on the Accepted Programme. That “later of” is subtle and important. (NEC3 & NEC4.)

D) Stop/Not to start — Clause 34.1

The PM can instruct you to stop or not to start any work. Under NEC4 the PM subsequently instructs to re-start/start or to remove the work from the Scope—this extra follow-on instruction is clearer than NEC3’s simpler “may later instruct to restart.” (NEC4 & NEC3.)

E) Late access is a compensation event — Clause 60.1(2)

If the Employer/Client does not allow access by the later of the access date and the date shown on the Accepted Programme, it’s a CE—opening time and money relief routes. (NEC3 & NEC4.)

And yes—CE process mechanics (notify, quote, assess, implement) and time modelling (delay = delta to planned Completion on the Accepted Programme) are explicitly set out in clauses 61–65 and 63.

3️⃣ Key interpretations & practical implications (with the “why” behind NEC4 tweaks)

“On the Site” means… only on-Site work is barred pre-access

30.1 restricts physical work on the Site pre-access; off-site design, procurement, fabrication can proceed to protect the Completion Date—just make sure the programme shows it, and that any pre-start acceptances are timed. (See the programme content rules.)

The sneaky “later of” in 33.1

Access is compliant if given by the later of the access date and the Accepted Programme date. Translation: if you’ve pencilled in earlier access on your programme than the Contract Data access date, a slip to the Contract Data date alone is not automatically a CE. Keep your time risk allowances and float honest.

Late access? Use the CE route fast

If access misses even the later of the two dates, notify a 60.1(2) CE, keep contemporaneous records, and update the Accepted Programme to show the delay’s effect on planned Completion. That is the yardstick for time relief under 63.5 (NEC4) / 63.3 (NEC3).

PM’s “do not start” instruction under 34.1

If the PM instructs “not to start,” comply—but push for clarity on restart conditions. NEC4 added a crisper obligation on the PM to later instruct restart or removal from Scope, which reduces the limbo of unresolved stoppages. If a stop/not-start drifts past thirteen weeks with no resolution, it even feeds into termination triggers (both editions, 91.6).

NEC3 ➜ NEC4 “why the polish?”

Terminology modernised (Employer→Client; Works Information→Scope)—but the commencement rule itself is unchanged.
34.1 gains a required follow-up instruction (restart or remove from Scope), improving certainty when commencement is paused.

4️⃣ Cross-referencing that really matters (how commencement interacts)

31.2 Programme: Must show starting/access dates, Key Dates, Completion Date, interfaces and what you’ll need (access later than access date, acceptances, Client-provided items, information). This is how you demonstrate readiness to commence and how you prove impacts if access slips. (NEC3 & NEC4.)
32.2 Revising the programme: Submit updates at intervals stated from starting date until Completion—your living evidence for time effects. (NEC3 & NEC4.)
33.1 Access: “Later of” rule—align your expectations. (NEC3 & NEC4.)
34.1 Stop/Not to start: PM’s authority; NEC4 adds the follow-on instruction.
60.1 Compensation events: Late access = CE; PM “not to start” = CE; non-replies = CE, etc. (both editions).

5️⃣ “What-If” Scenarios 🧩 (walkthroughs you can copy-paste into your playbook)

Scenario A — Partial access only (Area A open, Area B closed)

Do: Start in Area A (you have access), hold off Area B until its first access date (30.1).
If Area B access is late against the later of Contract Data access date and your programme date, notify CE under 60.1(2), record effects, and submit a revised programme under 32.

Scenario B — PM says “do not start” even though access is fine

Comply with 34.1. Ask for the reason and the conditions to re-start (NEC4 expects the PM to later instruct restart or removal from Scope).
Watch the clock: if no restart/removal within thirteen weeks, this lands in 91.6 territory (possible termination rights depending on cause).

Scenario C — Off-site fabrication before access dates

Allowed. 30.1 only restrains work on the Site. Keep acceptances and logistics visible on the programme and avoid premature deliveries that rack up costs without benefit. (See 31.2 content list.)

Scenario D — You planned earlier access than Contract Data

If the Client provides access by the Contract Data access date but later than your programme’s earlier date, that alone isn’t a CE because 33.1 uses the later of the two dates. Manage your float and time risk allowances.

6️⃣ Suggestions to sharpen clarity (editions-agnostic, but NEC4 pairs nicely)

Define access in “zones.” In Contract Data, break the Site into sub-areas with their own access dates (Area A/B/C…) so “commencement” can phase cleanly and disputes don’t hinge on fuzzy boundaries. (Align these with your 31.2 breakdown.)
Pre-start prerequisites list in the Scope: Permits, method statements, safety plans, critical acceptances, third-party outages—make visible what must be in place before starting on Site; it justifies a 34.1 hold if something’s missing and avoids unsafe starts.
Programme hygiene: Show time risk allowances and float transparently; when a CE hits (like late access), the delay calculation in 63.3/63.5 relies on planned Completion on the Accepted Programme.
CE playbook: Pre-draft a “Late Access” notification (name the sub-area, the access date missed, and the later-of test), attach contemporaneous records, and include a programme impact extract. Implement per 61–65 to lock in relief swiftly.

7️⃣ Final takeaways (and a few prompts to sanity-check your strategy) ✅

Commencement = access gate. You may mobilise off-site, but do not start on the Site before the first access date (Clause 30.1).
Programme is king. Keep starting date, access dates, interfaces, and risk allowances visible (31.2). It’s your defence and the PM’s reference point.
Late access? Trigger CE. 60.1(2) protects you when access misses the later of the two dates (Contract Data vs Accepted Programme).
PM can pause start. 34.1 lets the PM instruct “not to start”; in NEC4, they must later instruct restart or removal from Scope. Prolonged pause (thirteen weeks) touches 91.6 termination paths.
NEC3 ➜ NEC4: Substance unchanged for commencement; process clarity improved (terminology, follow-up on stoppages).

Quick interpretative questions to ask yourself 🤔

Can it be interpreted that off-site works may commence before access dates? Yes—30.1 only restrains work on the Site; just keep the programme and acceptances tight.
If I show earlier access on my programme, is a slip to the Contract Data access date a CE? Not by itself—the 33.1 “later-of” rule governs.

Commencement of Works: NEC3 vs NEC4 (Clause 30.1)