Progress measurement and rules of credit
Last reviewed 9 September 20262,293 words10 min read
0/100, 20/80, steps
🟩 In one line: A rule of credit is an agreed formula that turns physical work into a percent complete before anyone is asked for an opinion — pick the rule per activity type, write it in the SBM, and use it identically every month, because a percent that comes from a rule can be audited and a percent that comes from a foreman's estimate cannot.
👤 Who this is for: J/M. You should know what Physical % Complete is in P6 and how the monthly update works. Seniors: the argument in ⚖️ about subcontractor payment is the part worth re-reading.
First, let's be honest about why this page exists
Most progress percentages on Gulf sites are guesses. A section engineer looks at a floor, says "about 70%", and that number goes into P6, into the S-curve, and into the subcontractor's payment application. Next month the same engineer says 75% when the work is actually 85%, or 90% when it's 75%, and the S-curve records a trend that never happened. Six months later nobody can say when the job actually fell behind.
A rule of credit removes the opinion. It says: rebar fixed earns 40%, formwork closed earns another 30%, poured earns the last 30% — for every slab, every month, whoever is reporting. It takes an afternoon to set up and it is the difference between a progress record and a mood diary.
🟨 The standard — what "good" looks like
| Source | What it says (paraphrased) |
|---|---|
| EIA-748 (ANSI/EIA-748) EVMS Standard — Guideline 7 and earned value techniques | Earned value must be measured using objective methods: discrete techniques (0/100, 50/50, weighted milestones, percent complete with objective criteria, units complete), apportioned effort, and level of effort only where no discrete measure exists. |
| PMI The Standard for Earned Value Management (2019) / Practice Standard for EVM, 2nd ed. | Measurement method chosen by work type and duration; fixed-formula methods for short activities, weighted milestones or units complete for longer ones; the method fixed at baseline and not changed during execution. |
| GAO Cost Estimating and Assessment Guide — EVM chapter | Percent complete based on subjective judgment is the least reliable technique; LOE should not exceed a small share of the baseline. |
| NDIA EVMS Intent Guide | Rules of credit should be documented, objective and consistently applied; changes to the method require change control. |
| AACE International RP 86R-14, Variance Analysis and Reporting | Progress measurement basis must be documented so that variances can be traced to cause. |
| DCMA 14-Point — Metric 9 (Invalid Dates) | Actual dates after the data date, or planned dates before it, indicate statusing not based on physical progress. |
| P6 Professional User Guide — Activity Steps; Percent Complete Types | Physical % Complete may be calculated from weighted steps when "Activity percent complete based on activity steps" is set in Project Details → Calculations. |
🟢 Rule: one rule of credit per activity type, written in the SBM, weighted by manhours or cost, applied through P6 steps or a controlled quantity sheet — never overwritten by an opinion.
How it actually works
1. The methods, and where each belongs.
| Method | How it works | Use it for | Don't use it for |
|---|---|---|---|
| 0/100 | Nothing until finished, then all | Activities under two update periods; inspections, tests, deliveries, permits | Anything spanning three or more updates — the S-curve flatlines then jumps |
| 50/50 | Half at start, half at finish | Short activities up to two periods where some progress credit is wanted | Anything longer; anything where "started" is easy to claim |
| 20/80, 25/75, 40/60 | Small credit at start, balance at finish | Two- to three-period activities where mobilisation is real work | Long activities |
| Weighted milestones / steps | Fixed percentages at defined physical points | Activities of three or more periods with recognisable stages: slab (rebar/formwork/pour), pipework (support/erect/weld/test), façade (bracket/panel/seal) | Activities with no clear intermediate stages |
| Units complete | Quantity installed ÷ total quantity | Repetitive measured work: blockwork m², cable m, pile count, panels | Work where quantity doesn't track effort (a single 20 m vessel) |
| Percent complete (assessed) | Judgement against a checklist or standard | Only where none of the above fits; must have written criteria | Default choice — it is the last resort, not the first |
| Apportioned effort | Follows a base activity at a fixed ratio | QA/QC, inspection linked to a production activity | Anything independent of the base |
| Level of effort | Passes with time | Supervision, scaffold, hoists, site services | Any production work; keep LOE under 5–10% of the baseline |
2. Building steps in P6. Project → Details → Calculations → tick Activity percent complete based on activity steps. On each activity set Percent Complete Type = Physical. Activities → Steps tab → add steps with a Step Weight. P6 converts weights to percentages; ticking a step's Completed box earns it. Step Templates (Enterprise → Activity Step Templates) let you build the slab template once and assign it to 80 slab activities.
3. Weighting the steps. Weight by manhours or cost, not by count. Three steps of equal weight on a slab overstates rebar and understates the pour. A typical suspended-slab split on a Gulf building — verify against your own crew data — is rebar 40%, formwork 30%, pour and finish 30%. State the split in the SBM.
4. Units complete outside P6. For blockwork, plaster, cable, pipe: a quantity sheet per activity (or per zone) with BOQ quantity, quantity installed this period, cumulative, percent. That percent goes into P6 Physical % Complete. The sheet is the audit trail; P6 holds the result. See quantity-tracking-and-physical-progress.
5. Rolling up. Activity percent must be weighted when rolled to WBS or project level. Weight by baseline manhours (resource-loaded) or baseline cost (cost-loaded). P6's WBS percent complete uses duration by default unless the project setting is changed — Project → Details → Settings → Define Critical Activities is on the same tab as Project % Complete... verify in the version: the summary percent complete uses the Earned Value settings under Project → Details → Calculations. Never roll up by activity count.
6. Remaining duration is separate. Physical % Complete of 60% does not mean 40% of the duration remains. If the activity was 20 days, 12 days used, 60% done, remaining duration might be 8, or 15 if productivity fell. Enter remaining duration from the section engineer's forecast, not from the percent. See forecasting-honestly.
📜 Rules of credit and subcontractor payment
The subcontract should state the rules of credit and they should be the same as the main programme's. If the subcontractor's payment application uses 50/50 and the main schedule uses steps, their 80% will be your 55% every month and the argument never ends. Write the rule into the subcontract progress-measurement schedule, attach the step templates, and make payment for an activity conditional on the step's inspection record. See verifying-subcontractor-progress.
Under FIDIC interim payments (1999 Cl 14.3 / 2017 Cl 14.3) the Statement is for work executed; a percent that comes from a rule of credit tied to inspections is a defensible measure of "executed". Under NEC the Price for Work Done to Date (Cl 11.2) is measured against the Activity Schedule or Bill; the same principle applies.
🟥 Where people go wrong
- Percent complete by feel. "About 70%" is not a measurement. If there's no rule, no quantity and no step, the number is unauditable and will be challenged in the first dispute.
- Steps of equal weight. Rebar, formwork and pour are not equal effort. Weight by manhours.
- Changing the rule mid-project. Switching a package from 50/50 to steps in month eight makes the S-curve step-change. If the rule must change, do it with a baseline revision and say so.
- Duration % Complete on production activities. P6's default type earns credit as the data date passes. It says nothing about the work. Physical or Units only for production.
- Too much LOE. Supervision, scaffold, hoists and "general attendance" at 25% of budget means a quarter of the S-curve moves with the calendar regardless of what happens on site.
- Claiming the step before the inspection. The pour is earned when the pour card is signed, not when the truck arrives. Tie each step to a record.
- Rolling up by activity count. Ten small activities done and one large one not started reads 91%. Weight by manhours or cost.
⚖️ When you're challenged
"The subcontractor says 80%. You've got 55%. Who's right?" Their application uses 50/50 on every activity so every started item earns half. Our schedule earns by step: bracket fixed 20%, panel hung 50%, sealed and inspected 30%. Of 120 panels, brackets are done on all, panels hung on 70, sealed on 30. That's 55.5%. The step weights are in the subcontract, Appendix 4.
"Why did progress jump 9% this month? Nothing changed on site." Twelve inspection activities on 0/100 were signed off in the last week of the period. The work was done over the previous two months; the rule earns it at sign-off. That's why 0/100 is only used on activities under two periods and why the S-curve should be read with the quantity sheet.
"Just use duration percent, it's simpler." It earns progress because time passed. A slab 10 days into a 20-day duration shows 50% whether it's poured or still bare formwork. The Employer's schedule spec requires physical progress, and so does the payment mechanism.
"Can we change the plaster rule to units so the curve looks better?" Units is the right method for plaster and should have been used from the start. If we change it now it's a baseline revision, recorded in the change table and the SBM, with the previous method's curve kept for comparison. I won't change it silently.
📄 Related pages
- Percent Complete Types — Duration, Physical and Units in P6.
- Quantity tracking and physical progress — the sheet underneath units complete.
- Verifying subcontractor progress — when their 80% is your 55%.
- Statusing a schedule — where the percent gets entered.
- Forecasting honestly — why remaining duration is separate from percent.
- Earned Value Basics: SPI and CPI — what the percent feeds.
- S-Curves: Early, Late and Actual — how the rule shapes the curve.
- Schedule Basis Memorandum — where the rules are recorded.
✏️ Worked example
An office tower in Riyadh, 22 suspended slabs, each a single activity of 12 working days. Step template weighted by crew manhours from the SBM.
| Step | Weight | Evidence to earn |
|---|---|---|
| Rebar fixed and inspected | 40% | Consultant inspection request signed |
| Formwork and MEP sleeves closed | 30% | Pre-pour checklist signed |
| Pour and finish complete | 30% | Pour card and cube register entry |
Update 07, data date 25 May 25, Levels 9–12:
| Level | Rebar | Formwork | Pour | Physical % | Remaining duration (engineer's forecast) |
|---|---|---|---|---|---|
| L9 | ✓ | ✓ | ✓ | 100% | 0 |
| L10 | ✓ | ✓ | — | 70% | 3 d (pour booked 28 May) |
| L11 | ✓ | — | — | 40% | 8 d |
| L12 | — | — | — | 0% | 12 d (not started; start 2 Jun) |
What the section engineer had said before steps were introduced (Update 06 method — assessed percent): L10 "90%, just the pour left"; L11 "60%". Under steps, L10 is 70% (the pour is 30% of the effort, not 10%) and L11 is 40%. The S-curve dropped 2.1% overall when the method was corrected at the baseline revision in Update 06 — recorded in the change table with both curves shown — and has tracked the pour register within 1% every month since.
Roll-up check: the four slabs weighted by baseline manhours (equal in this case) give 52.5%. By activity count it would have read 25% complete (one of four finished) — meaningless.
📖 References
- ANSI/EIA-748, Earned Value Management Systems — Guideline 7; earned value techniques (check against your copy).
- PMI, The Standard for Earned Value Management (2019); Practice Standard for Earned Value Management, 2nd ed. (2011).
- GAO-20-195G, Cost Estimating and Assessment Guide — EVM chapter (check against your copy).
- NDIA Integrated Program Management Division, EVMS Intent Guide.
- AACE International RP 86R-14, Variance Analysis and Reporting.
- DCMA 14-Point Schedule Assessment — Metric 9, Invalid Dates.
- FIDIC 1999 / 2017 — Cl 14.3; NEC4 ECC — Cl 11.2 (check the edition in your contract).
- Oracle Primavera P6 Professional User Guide — Activity Steps; Step Templates; Percent Complete Types; Project Details, Calculations.
From the field
Experience from working planners. Unreviewed — read it as experience, not guidance.
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