Loss of productivity: how it is measured, and the records that make it measurable
The drywall crew says the upper floors took far longer because the corridors were crowded. Hours are available, but board counts and crew conditions were not recorded consistently. The project manager cannot tell how much of the difference reflects comparable work.
Record quantities completed, the labour used and the conditions affecting the same defined work. A qualified reviewer needs that information to investigate a productivity change. The Society of Construction Law describes measured-mile analysis as comparing identical or similar activities in disrupted and unaffected periods, with adjustments and other influences considered. Its protocol has a UK focus and does not decide Canadian entitlement. A rate difference alone is not proof that every additional hour belongs in a claim.
Keep records that support a fair comparison
- Define the work and quantity unit. Identify the location, activity and what counts as completed output. Record consistent units and relevant differences in type, dimensions or complexity. A sheet count is only useful if a reviewer can understand what those sheets and the associated operation represent.
- Record hours against that activity. Capture crew composition, assigned labour and the period covered on a consistent basis. Distinguish installation, other tasks, rework and waiting where the project records allow. Do not divide all job hours by one trade's installed quantity and call it a comparable rate.
- Describe the dated conditions. Note access, congestion, instructions, sequencing and other observed influences with locations and supporting records. Keep facts separate from assumed causes. Preserve evidence of ordinary working periods too; a useful comparison needs a credible baseline, not only photographs taken when the crew struggles.
- Check comparability and competing explanations. Give the reviewer changes in crew experience, geometry, material, learning, equipment and other site conditions. Explain missing records and changes in collection method. A period selected as unaffected still needs examination rather than being accepted because its rate is lower.
- Have the analysis and claim reviewed. Reconcile the source data and explain any exclusions or adjustments with qualified assistance. Keep the observed difference, analysis of causes and requested commercial remedy distinct. Applicable methods, contract requirements and recoverability need their own review before the comparison becomes a submitted claim.
Common mistakes
- Recording hours but no consistent completed quantities.
- Selecting a favourable baseline without checking differences in work.
- Assigning the entire rate gap to one observed disruption.
Checklist
The evidence behind a productivity comparison
- Defined activity and location.
- Consistent completed-output unit.
- Matched hours and crew records.
- Dated affected and ordinary conditions.
- Other influences and missing data identified.
- Qualified analysis and commercial review.
Check your understanding
Two periods show different hours per sheet, and the slower period had crowded corridors. Does the gap prove the claim?
