Erection Sequence Calculator
Plan precast erection: estimate crane picks per day, total erection days, crew size, and project cost.
About this calculator
Precast erection schedules run on a simple rhythm: pick, swing, set, plumb, connect, swing back, repeat, and this calculator turns that cycle time into a daily pick count, then divides total panels by that count to get erection days. Weather and delay time comes off the top as a percentage of the work day before the cycle-time math runs, so a 10% weather factor on an 8-hour day leaves 7.2 productive hours to divide into picks — not 8 hours minus 10% of the final pick count. Required crane capacity is driven entirely by the single heaviest panel in the job, not the average, with a 1.25 multiplier for rigging and dynamic pick loads; the average panel weight input mostly just sets a floor under the heaviest-panel figure; if you enter a heaviest panel lighter than the average, the calculator quietly raises it to match the average, since a project's heaviest single panel can never really be less than the mean panel weight.
Crew size is fixed at six regardless of job size — a typical crane operator, oiler, two connectors, a signalman, and a plumber — so it does not flex for larger or smaller crews the way the cost and schedule numbers do. Mobilization and demobilization cost is a step function of the required crane capacity, jumping between four price bands rather than scaling smoothly, which is worth knowing if your required capacity sits close to one of those band edges.
Inputs
Results
Picks per day
9
How to Use This Calculator
- Enter the total number of precast panels and the average and heaviest panel weights in lbs.
- Set the cycle time per crane pick in minutes (including set, plumb, and weld) and work hours per day.
- Enter the weather/delay factor (%) and the crane hourly rate and ironworker burdened labor rate.
- Read Picks per Day and Total Erection Days to set your schedule.
- Check Min Crane Capacity (lbs) — this is the heaviest piece times 1.25 and sets the minimum crane size.
- Review Erection Cost, Labor Cost, and Total Project Cost for budget planning and subcontractor negotiation.
How the result changes with Cycle time per pick
| Cycle time per pick | Picks per day |
|---|---|
| 23 | 18 |
| 34 | 12 |
| 68 | 6 |
| 113 | 3 |
What each input means
- Total panels/pieces
- Total number of precast pieces to erect.
- Average panel weight
- Average weight per precast piece.
- Heaviest panel weight
- Weight of the heaviest piece (determines crane size).
- Cycle time per pick
- Average time per crane pick including set, plumb, and weld.
- Work hours per day
- Productive work hours per day.
- Weather/delay factor
- Estimated percentage of time lost to weather/delays.
- Crane hourly rate
- All-in crane rental rate per hour.
- Labor rate per person
- Burdened labor rate per crew member per hour.
What each result means
- Picks per day
- Number of precast pieces that can be set per day.
- Total erection days
- Calendar work days to complete erection.
- Min crane capacity
- Minimum crane capacity (heaviest piece × 1.25).
- Crew size
- Recommended erection crew size.
- Crane cost
- Total crane rental cost.
- Labor cost
- Total erection labor cost.
- Erection cost
- Combined crane and labor cost.
- Cost per panel
- Average erection cost per panel.
- Mob/demob estimate
- Estimated crane mobilization and demobilization cost.
- Total project cost
- All-in erection cost including mob/demob.
- Crane utilization
- Crane utilization efficiency.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersTotal panels/pieces = 50, Average panel weight = 12000, Heaviest panel weight = 18000, Cycle time per pick = 45 = 8 input(s) provided
- Calculate Picks per dayPicks per day = max(1, picksPerDay)9 = 9
- Calculate Total erection daysTotal erection days6 = 6
- Calculate Min crane capacityMin crane capacity = heaviestPanel * 1.2522500 = 22500
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why doesn't average panel weight change the crane capacity or cost?
Because required crane capacity is set by the single heaviest panel on the job, not the average — a crane sized for the mean weight could still fail to lift the heaviest piece. Average panel weight only matters as a floor: if you type in a heaviest-panel figure that's lower than the average, the calculator raises it back up to match, since the true heaviest panel can never be lighter than the mean.
How is weather delay time actually applied to the schedule?
It's subtracted from the work day before the pick-rate math runs, not from the final pick count. An 8-hour day with a 10% weather factor becomes 7.2 productive hours, which then gets divided by cycle time to find picks per day — so weather delay compounds through the whole schedule rather than just shaving picks off the end of an otherwise full day.
Does crew size scale up on bigger erection jobs?
No — this calculator uses a fixed six-person crew (crane operator, oiler, two connectors, signalman, and plumber) regardless of total panel count or job size. Larger projects that run parallel crews or add a second crane need to be modeled as separate erection sequences, since the cost and schedule math here assumes one crew working one crane.
Why does mobilization cost jump instead of scaling smoothly with crane size?
Mob/demob pricing here uses four flat price bands tied to required crane capacity (roughly $5,000 up to $10,000 up to $18,000 up to $25,000) rather than a continuous rate, which mirrors how crane rental quotes actually work — a bigger class of crane means a different rig and crew to bring it in, not a proportionally bigger version of the same machine.
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