Change Control in a Live Schedule
Last reviewed 9 September 20262,492 words11 min read
A variation arrives — what to do, in what order, and what never to touch
🟩 In one line: A change is modelled in a Reflection, quoted through the contract mechanism, and only then incorporated into the live schedule under its own reference — the live schedule is never edited on the day the instruction lands.
👤 Who this is for: J/M/S. Prerequisites: fragnets, time-impact-analysis, notice-requirements-and-records, baseline-approval-and-control.
First, let's be honest about why this page exists
The commonest failure is speed in the wrong place. The site instruction arrives on Tuesday, the planner adds three activities to the live schedule on Wednesday, the monthly update goes out on Friday with the completion date moved 11 days and no record of why. Six months later nobody can separate the variation's effect from the contractor's own slippage, and the claim is worth half what it should have been.
The second commonest failure is the opposite: waiting for the formal instruction before doing anything, then discovering the NEC quotation clock ran out three weeks ago or the FIDIC 28-day notice was missed. This page sets the order so that both mistakes are avoided.
🟨 The standard — what "good" looks like
| Source | What it asks for (paraphrased) | Practical consequence |
|---|---|---|
| FIDIC 1999 Cl 13.1, 13.3 | Engineer may instruct or request a proposal; Contractor responds with programme and cost implications; Contractor proceeds with instructed variations | Model the time effect before or alongside the price |
| FIDIC 2017 Cl 13.3.1, 13.3.2 | Variation by Instruction / by Request for Proposal; Contractor's submission includes the programme effect and any EOT required | Two distinct routes with different obligations — tag which one applies |
| FIDIC 1999 Cl 20.1 / 2017 Cl 20.2.1 | Notice within 28 days of awareness | Notice is separate from the variation response; both clocks run |
| NEC3/NEC4 Cl 60.1(1), 61.3 | Change to Works Information / Scope is a compensation event; notify within 8 weeks (where PM has not) | The change enters the CE register on day one |
| NEC3/NEC4 Cl 62.2, 62.3 | Quotation includes alterations to the Accepted Programme; submitted within 3 weeks, PM replies within 2 weeks | The revised programme extract is part of the quotation, not an afterthought |
| NEC3 Cl 63.3 / NEC4 Cl 63.5 | Delay to Completion Date = the delay to planned Completion shown on the Accepted Programme | The impact is measured on the last Accepted Programme, never the original |
| NEC3 Cl 65 / NEC4 Cl 66 | Implementing the CE: Prices, Completion Date and Key Dates changed when agreed or assessed | Only then does the live schedule carry the new contractual date |
| SCL Protocol 2nd ed., Core Principles 4 and 5 | Do not "wait and see"; EOT assessed contemporaneously on an updated programme | Build the fragnet now, not at final account |
| SCL Protocol 2nd ed., Core Principle 19 | Variations valued with their time effect recognised | Time and money travel together |
| AACE RP 52R-06 | TIA: fragnet inserted in the last update before the event | The method for step 6 below |
| PMI Practice Standard for Scheduling, 2nd ed. | Schedule changes controlled through a documented change process | The register and the change table |
🟢 Rule: log it, notice it, model it in a Reflection on the last accepted update, quote it, and incorporate it under its own change reference — in that order, every time.
How it actually works
The eleven steps
| # | Step | Where it happens | Timing |
|---|---|---|---|
| 1 | Log it — change register entry: ref, date received, source document, instruction or proposal, notice deadline, quotation deadline | Excel register (or the CE/VO register the commercial team keeps) | Day received |
| 2 | Classify — is it an instruction to proceed, a request for a proposal, or an RFI that may become one? | Register | Day received |
| 3 | Notice — confirm the contractual notice has gone or goes now; record the reference | Commercial / contracts | Within 28 days (FIDIC) / 8 weeks (NEC) — aim for 7 days |
| 4 | Freeze the live schedule — no edits for this change in the production project | P6 | Until step 10 |
| 5 | Build the fragnet — Reflection of the last accepted update; new WBS node "VO-012 …"; activities from the scope; durations from SBM rates; hard logic only; one FS in, one FS out | P6 → Project → Create Reflection | Days 1–5 |
| 6 | Impact it — schedule the Reflection; Schedule Comparison against the source; read the movement of the contractual completion milestone and any Key Dates | P6 → Tools → Schedule Comparison | Days 3–7 |
| 7 | Quote time and cost — programme extract, TIA result, resource/cost build-up; state the basis (data date, source update, SBM rates) | Commercial + planning | FIDIC per Cl 13.3 request; NEC within 3 weeks |
| 8 | Archive — Reflection XER, Schedule Comparison report, fragnet narrative, filed per change ref | Project archive, read-only | Same day as quotation |
| 9 | Await instruction/agreement — nothing enters the live schedule yet, unless the work is instructed to proceed (then step 10 happens with the time effect still "claimed, not agreed") | — | Per contract |
| 10 | Incorporate — copy the fragnet into the live schedule (Reflection → Merge, or manual re-entry) under the VO WBS node, activity code Change Ref = VO-012, Notebook topic "Change Basis" on each activity | P6 | Next update cycle after instruction |
| 11 | Report and close — narrative change table lists the new activities and any logic altered; register shows status (quoted / instructed / agreed / implemented); when the EOT is awarded, the contractual milestone constraint moves and the baseline register is updated if a revision is triggered | Narrative + registers | Every update until closed |
Two kinds of change, one change table
| Kind | Example | Goes through the contract mechanism? | Goes in the narrative change table? |
|---|---|---|---|
| Scope change (variation / CE) | Additional isolation rooms; revised façade spec | Yes | Yes |
| Schedule change (planner's edit) | Logic re-sequence; calendar amendment; duration correction | No | Yes — every one |
The change table in every narrative lists both. The register tracks only the first kind. Reviewers can then see what the contract changed and what the planner changed, separately.
P6 housekeeping that makes this work
- Activity code "Change Ref" (project-level, values = VO/CE numbers). Filter on it and every variation's footprint appears in one view.
- WBS node per change under a parent node "Variations". Rolls up cost and hours per change without a Global Change.
- Notebook topic "Change Basis" on every added activity: source document, duration basis, date incorporated, status.
- Constraint on the contractual completion milestone is moved only when an EOT is awarded in writing — never when it is quoted or claimed. Until then, negative float against the milestone is the correct picture and the narrative says why.
- Naming: Reflection saved as "VO-012 Impact — Reflection of Upd 07 DD 01Aug"; the Schedule Comparison PDF carries the same name.
📜 What changes when the work is instructed but the time is not yet agreed
Under FIDIC the Contractor proceeds with an instructed variation (1999 Cl 13.1; 2017 Cl 13.3.1) regardless of whether the EOT is agreed. Under NEC the PM may instruct the change and the CE is assessed in parallel (Cl 61–64). In both cases the activities go into the live schedule at step 10, the completion milestone stays where the contract currently puts it, and the resulting negative float is reported with a sentence: "Negative float of −9 days reflects VO-012 instructed 14 Aug, EOT claimed under Cl 8.4, not yet determined." That sentence is the contemporaneous record the SCL Protocol asks for. Removing the negative float by moving the milestone early is the error that later reads as acceptance of the delay.
🟥 Where people go wrong
- Editing the live schedule the day the RFI arrives. The change is then indistinguishable from everything else that moved that month. Reflection first, always.
- Waiting for the formal instruction before modelling. NEC gives three weeks for the quotation; FIDIC's 28-day notice runs from awareness, not from instruction. Build the fragnet on receipt of the request and keep it in the archive.
- Absorbing variation work into existing activities. Extending "L5 Blockwork" by 6 days to cover extra walls makes the variation invisible. Every change gets its own activities, its own WBS node and its own code.
- Impacting on the baseline instead of the last accepted update. Both contracts and AACE 52R-06 point to the current programme. An impact on the baseline is an impact on a project that no longer exists.
- Quoting time without cost, or cost without time. The planner produces the days; the QS produces the money; the two are submitted together or the submission is incomplete under Cl 13.3 / Cl 62.2.
- Moving the completion milestone when the EOT is claimed. It moves when the EOT is awarded in writing, and the baseline register records it. Until then, negative float and a sentence explaining it.
- A register that only grows. Every entry needs a status and a close-out date. A change register with 140 open items tells the reviewer that nobody is running it.
⚖️ When you're challenged
"The Engineer just wants to know the delay. Why do you need a week?" Because the answer has to survive. A fragnet built on the last accepted update, impacted in a Reflection with the comparison archived, is an answer we can defend at final account. A number from memory isn't. Five working days, and the notice has already gone so no clock is at risk.
"Can't you just add the activities to the live programme? It's only three items." I will — at step ten, under their own code, once it's instructed. If I add them now, next month's slippage has the variation mixed into it and we can never take it out again.
"Your quotation shows 9 days but your programme shows completion moved 21. Which is it?" Both. Nine days is the variation's own effect on the accepted programme, and that's what we're claiming for it. The other twelve are our slippage on the structure and they're reported separately in the trend table. Mixing them would overstate the claim and understate our problem.
"The VO was instructed. Move the completion date." The instruction lets us start the work. The completion date moves when the Engineer determines the EOT under 8.4. Until then the programme shows negative float against the contractual milestone with the reason written next to it — that is the correct position, and it protects the claim.
📄 Related pages
- Fragnets — how the VO-014 node is built
- Time Impact Analysis — the impact method behind step 6
- Notice Requirements and Records — the clocks in step 3
- P6 Reflections and What-If — the sandbox used in step 5
- P6 Schedule Comparison — the archived proof in steps 6 and 8
- Schedule Narrative — where the change table lives
- Baseline Approval and Control — when an award becomes a baseline row
- Revised Baseline vs Recovery Schedule — what an accepted EOT does and does not trigger
✏️ Worked example
A hospital fit-out in Riyadh, FIDIC 1999 conditions, 6-day calendar. On 12 August the Engineer issues a request under Cl 13.3 for a proposal to add four isolation rooms on Level 3, requiring new partitions, ducting changes and a dedicated exhaust unit. Last accepted update: Upd 07, data date 1 August, forecast completion 20 November, contract completion 15 November (float −4 already, own slippage).
| Step | Date | Action | Record |
|---|---|---|---|
| 1–2 | 12 Aug | Register entry VO-014, "request for proposal", quotation due per Engineer's letter 26 Aug | Register |
| 3 | 14 Aug | Notice under Cl 20.1 issued (letter ref C-231) — 2 days after awareness | Letter ref in register |
| 4–5 | 13–17 Aug | Reflection of Upd 07; WBS node "VO-014 Isolation Rooms L3"; six activities | See fragnet table |
| 6 | 18 Aug | Reflection scheduled; Schedule Comparison vs Upd 07 | Completion moves 20 Nov → 1 Dec |
| 7 | 24 Aug | Proposal submitted: 9 working days EOT, priced build-up, programme extract | Submission ref P-062 |
| 8 | 24 Aug | XER + comparison report archived read-only | Archive folder VO-014 |
| 9–10 | 6 Sep instruction; incorporated in Upd 08 (DD 1 Sep, issued 5 Sep) | Fragnet merged; code Change Ref = VO-014 | Change table, Upd 08 narrative |
| 11 | 30 Oct | EOT of 9 days determined under Cl 3.5 / 8.4; contract completion → 26 Nov; baseline register row added (no full revision triggered) | Register closed |
Fragnet (durations from SBM rates, hard logic only):
| ID | Activity | Duration (days) | Predecessor | Successor |
|---|---|---|---|---|
| VO14-010 | Shop drawings & approval, isolation rooms | 10 | L3-MEP-040 (existing, FS) | VO14-020 |
| VO14-020 | Partition framing & boarding | 6 | VO14-010 | VO14-030 |
| VO14-030 | Duct modification & exhaust unit install | 7 | VO14-020 | VO14-040 |
| VO14-040 | Pressure test & DOP | 3 | VO14-030 | VO14-050 |
| VO14-050 | Finishes & doors, isolation rooms | 5 | VO14-040 | VO14-060 |
| VO14-060 | Room handover to commissioning | 0 (milestone) | VO14-050 | L3-COM-010 (existing, FS) |
Result written into the narrative: "VO-014 (instructed 6 Sep) adds 9 working days to the contractual completion path via Level 3 commissioning. Forecast completion 1 Dec comprises 9 days attributable to VO-014 (claimed, EOT ref C-231/P-062) and 4 days of Contractor slippage on structure previously reported." Two numbers, two causes, one sentence.
📖 References
- FIDIC Conditions of Contract for Construction, 1999, Cl 3.5, 8.4, 13.1, 13.3, 20.1; 2017, Cl 3.7, 8.5, 13.3.1, 13.3.2, 20.2 (check the edition in your contract)
- NEC3 / NEC4 Engineering and Construction Contract, Cl 60.1(1), 61.3, 62.2, 62.3, 63.3 (NEC3) / 63.5 (NEC4), 65 (NEC3) / 66 (NEC4) (check the edition in your contract)
- SCL Delay and Disruption Protocol, 2nd ed. (2017), Core Principles 4, 5, 19
- AACE International RP 52R-06, Time Impact Analysis – As Applied in Construction
- PMI Practice Standard for Scheduling, 2nd ed., schedule change control
- Oracle Primavera P6 Professional User Guide — Reflections; Schedule Comparison; Activity Codes; Notebook topics
From the field
Experience from working planners. Unreviewed — read it as experience, not guidance.
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