A construction schedule built from the same takeoff as the estimate lets you test cost and time together: durations come from quantities and labor hours, time-related general conditions follow the calendar, and delays can be measured against a documented baseline. Priced separately, the estimate and the schedule drift apart, and the gap usually shows up as lost margin.
This guide explains how estimators and project managers connect the two, what a CPM schedule needs to be useful, and where a schedule belongs in the bid process.
What is a CPM schedule?
The critical path method models each activity with a duration and logic ties to its predecessors and successors. The software calculates the longest path of connected activities, the critical path, and the float on every other activity. Float is the time an activity can slip without moving the finish date. Activities with zero float are the ones the superintendent protects first. For terms such as float, look-ahead and baseline, see our glossary, and for a deeper standards view, PMI and AACE International publish scheduling practice guides.
How do quantities and labor hours become durations?
Durations start with the takeoff. For a given activity, divide the quantity by the crew's production per day to get crew-days, then adjust for access, sequence, inspection holds and weather. As an illustration of the method only: if a takeoff shows 6,000 square feet of floor tile and a crew is assumed to set a given number of square feet per day, the quotient is the number of crew-days, and a second crew halves the calendar time but raises mobilization and supervision cost. The same labor hours priced in the estimate drive the duration, so the two documents agree.
- Use the quantities from the quantity takeoff, not a rough area.
- Use production rates from your own history or a documented source, and write the assumption down.
- Carry long-lead items such as switchgear, elevators and curtain wall as procurement activities with submittal, review, fabrication and delivery durations.
Why does the schedule change the estimate?
Many general conditions are time-related: project management, superintendent, field office, temporary power, fencing, equipment rental, insurance and bonds for longer durations. A 10-month schedule and a 12-month schedule carry different general conditions even when the direct work is identical. Liquidated damages and early-completion incentives in the contract make the duration a pricing item too. Our Division 01 estimating page covers how those costs are built up.
How do you find the critical path and float?
- List the activities from the work breakdown structure, grouped by area and trade.
- Assign durations from the takeoff-driven crew-days.
- Link predecessors and successors with finish-to-start, start-to-start and lag where the work truly overlaps.
- Apply calendars: working days, holidays, weather days and owner restrictions.
- Calculate the schedule, identify the critical path, and test the logic by adding delays to near-critical activities.
Open ends, excessive constraints and long lags are the common logic errors. A schedule with many hard date constraints cannot show the true critical path.
How do look-ahead schedules help in the field?
A three-week look-ahead pulls activities out of the master schedule and adds the details field teams need: crew sizes, inspections, deliveries and constraints such as an unanswered RFI. Subcontractors commit to dates in the look-ahead, and the weekly update compares planned and actual progress. When a trade falls behind, the look-ahead shows who is waiting and what can be resequenced.
How does a schedule support delay documentation?
If a delay occurs, a baseline schedule, regular updates and daily reports show what was planned, what happened and which activities were on the critical path. Contracts differ on notice requirements, concurrent delay and time extensions, so follow the contract language and consult counsel for claims. The practical point for estimators is simple: a documented baseline made at bid or award is far easier to rely on than a schedule reconstructed after a dispute.
How do Primavera P6 and Microsoft Project compare?
Oracle Primavera P6 is common on commercial, industrial and public projects with detailed specification requirements. Microsoft Project is widely used on smaller and mid-sized projects. Both calculate a critical path; the difference is in resource handling, multi-project support and owner requirements. We build schedules in both and deliver native files with PDF output. See CPM scheduling services.
Where does the schedule fit in the bid process?
Public solicitations often require a preliminary schedule or milestone dates with the bid, and many specifications in Division 01 describe the format and update frequency. Build a short logic-based schedule before pricing general conditions, confirm the duration is realistic for the scope, and carry a note on any assumption, such as access hours or phasing around an occupied building. Our pre-bid process guide shows where this step sits, and budgeting and cost control covers tracking after award.
What should you ask a scheduling partner for?
- A baseline schedule in native format, so your team can update it.
- Activities tied to the estimate's cost codes.
- A written list of assumptions, calendars and constraints.
- A short narrative of the critical path and the main schedule risks.
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Frequently asked questions
What is a CPM schedule?
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A critical path method schedule models activities, durations and logic ties to find the longest path through the project. Activities on that path have no float; a delay to any of them moves the finish date.
How are activity durations estimated?
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Durations come from takeoff quantities, crew production rates and available working days. Quantity divided by crew output per day gives crew-days, which is then adjusted for access, sequencing and weather.
Why include a schedule in the bid?
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Time-related general conditions, liquidated damages and long-lead procurement all depend on the schedule. A bid priced without one can under-carry supervision, equipment and temporary facilities.
Which software do you use for schedules?
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We build schedules in Oracle Primavera P6 and Microsoft Project, and deliver native files plus PDF output.
Written by the Bid Sharp Estimating Team
Bid Sharp provides construction estimating, quantity takeoff, structural and permit drawings, shop drawings and scheduling for contractors across the United States. This article is general information, not legal or engineering advice.
