A production rates library: your own hours per unit, with the conditions that made them
The roofing estimator has one membrane labour rate in the workbook. It combines an open warehouse roof with a cut-up residential roof full of interfaces. The next townhouse bid resembles the second job, but the workbook hides which hours and quantities created the average.
Keep each rate with its measurement basis and the conditions that produced it. A useful library lets the next user decide whether a previous task resembles the planned one, rather than trusting a number because it appears in a company workbook. Start with a few well-described repetitive tasks. Preserve actual observations separately from allowances or chosen estimating rates, and describe the result in person-hours per unit so its direction is clear.
Build a rate record someone else can reuse
- Define the measured task. State its start and finish boundary, accepted quantity and unit. Identify whether preparation, details, handling, supervision or rework are included. Two records labelled membrane can describe different packages even when both use square metres.
- Reconcile hours and quantity. Use the task's actual time records and accepted completed quantity for the same period and boundary. Check shared personnel and corrections with the foreman. Keep a disputed quantity or incomplete time allocation out of the approved library until resolved.
- Calculate with labelled units. Divide person-hours by completed units for hours per unit. Keep any reciprocal output-per-hour figure separately labelled. Record the underlying totals as well as the result, so a later reviewer can check the calculation and compare its sample size.
- Attach relevant conditions. Describe access, height, geometry, interfaces, crew experience, repetition, work sequence and unusual interruptions. Choose conditions that explain transferability without writing a full diary into every record. Identify assumptions and missing information honestly.
- Separate observations from planning choices. Store the measured rate as historical evidence. When an estimator or foreman selects or adjusts it, record the intended scope and reasoning alongside the plan. An allowance for future uncertainty should not silently rewrite what the earlier crew achieved.
- Maintain the library deliberately. Give it an owner, searchable task names and a review date suitable for the business. Archive superseded or poorly described records with their reasons. Bring new job evidence into the review without averaging different conditions merely to produce one convenient company number.
Common mistakes
- Dropping the task boundary and units from a rate.
- Combining accepted quantities with unmatched hours.
- Overwriting historical results with estimating allowances.
- Averaging unlike conditions without retaining their separate records.
Checklist
Beside every reusable rate
- Defined task, unit and included scope.
- Accepted quantity and matching person-hours.
- Checkable calculation and sample size.
- Relevant conditions and interruptions.
- Separate planning selections and allowances.
- Owner, review date and change history.
Check your understanding
Two jobs have the same task name and unit but different included preparation. Can their rates be averaged for the next bid?
