Forecasting labour hours from the schedule: how many hours, which months, which trades
The monthly cost review looks acceptable because invoices are current. The foreman says the next floors contain more work than the staffing plan allows. The estimator has measured output from completed areas, but nobody has used it to forecast the hours still ahead.
Convert remaining work into forecast person-hours, then place those hours into the months when the schedule expects the work. Check the units before calculating: multiply quantity by hours per unit, or divide quantity by units per person-hour. Keep trades and work conditions distinguishable so a reassuring total does not hide an overloaded month. This forecast connects remaining scope, observed performance and staffing; it is not simply the unused balance of the budget.
Build the hours behind the staffing request
- Confirm remaining scope. Reconcile quantities and completed work with the current information and schedule activities. Separate changed scope, uncertain quantities and different work types before borrowing one production assumption for the whole package.
- Select a comparable achieved rate. Check which quantities and person-hours produced it, including the recorded support work. Ask the foreman whether access, complexity and crew conditions on the remaining work are comparable; label adjustments and uncertain assumptions.
- Calculate person-hours consistently. Write the rate's units beside the quantity and result. Distinguish a crew-hour from the sum of its members' person-hours, and keep work outside the rate's scope visible rather than silently leaving it out.
- Allocate work to months. Use the activity dates and intended output sequence, accounting for partial months and area releases. Do not spread hours evenly by calendar days when the crew plans most of the work in one part of the activity.
- Compare two separate baselines. Read forecast hours against remaining budget hours, then against confirmed package capacity for each month. A budget difference and a staffing shortage are different questions, even when they appear in the same table.
- Agree the response and update basis. Review quantity, rate, sequence and capacity choices with estimating and delivery. Record the selected assumptions, owners and next update date; preserve the earlier forecast so a changed rate does not erase the reason for the decision.
Common mistakes
- Multiplying quantity by a units-per-hour rate.
- Mixing one crew-hour with one person's hour.
- Moving forecast hours between months without changing the work plan.
Checklist
Your monthly hours table needs
- Remaining quantity and its information basis.
- Comparable achieved rate with explicit units.
- Forecast person-hours by work type and month.
- Remaining budget and confirmed package capacity.
- Unresolved difference, owner and next check.
Check your understanding
A completed area achieved a better rate, but the remaining area has restricted access. Should you use that rate unchanged?
