5 Common Primavera P6 Baseline Mistakes That Cause Rejections

The Cost of a Rejected Baseline

A rejected baseline schedule is more than an inconvenience — it delays mobilization, withholds payment applications, and signals to the owner that your team may not have a firm grasp on the project. In our experience reviewing hundreds of CPM schedules across federal, commercial, and data center projects, the same mistakes appear repeatedly.

Here are the five most common Primavera P6 baseline errors we see — and how to avoid them.

Mistake #1: Open-Ended Activities

This is the single most common reason for schedule rejection. An open-ended activity is one that lacks either a predecessor or a successor relationship. In a properly constructed CPM network, every activity must be logically connected — the only exceptions are the project start and completion milestones.

Open ends create "floating" activities that are not tied to the critical path analysis. This means delays to these activities will not show their true impact on the project completion date, rendering the schedule unreliable for both planning and forensic purposes.

Mistake #2: Over-Reliance on Constraints

Constraints override the CPM calculation engine. When you impose a "Must Start On" or "Must Finish On" constraint, you are telling P6 to ignore the logic network for that activity. While some constraints are necessary (contract milestones, permit dates), excessive use masks logic gaps and prevents the schedule from accurately predicting the impact of changes.

Owners and reviewers look for schedules driven by logic, not by imposed dates. If your schedule has more than a handful of constraints, expect questions.

Mistake #3: Unrealistic Activity Durations

Durations must reflect actual production rates for the scope of work assigned to each activity. A common mistake is assigning arbitrary round-number durations (5 days, 10 days, 20 days) without calculating based on quantities and crew productivity.

Reviewers will challenge activities with durations that seem too short (suggesting the work cannot physically be completed) or too long (suggesting the activity should be broken into phases or areas).

Mistake #4: Incomplete Activity Coding

Activity codes enable the schedule to be sorted, filtered, and summarized in meaningful ways. Federal contracts typically require codes for area/location, phase, responsible party, trade/discipline, and WBS level. Missing codes make the schedule difficult to analyze and indicate incomplete planning.

Beyond meeting specification requirements, proper coding is essential for earned value management, progress reporting, and resource analysis throughout the project lifecycle.

Mistake #5: No Narrative Report (or a Weak One)

Submitting a P6 file without a narrative report is like submitting drawings without specifications — the reviewer has no context for understanding your approach. Even when not explicitly required, a narrative demonstrates professionalism and gives the reviewer confidence in your planning.

A strong narrative includes an executive summary of the project approach, a description of the critical path and key driving sequences, phasing and area descriptions, identification of long-lead procurement items, known risks and assumptions, and a summary of key dates and milestones.

Prevention Is Better Than Correction

The time invested in getting the baseline right pays dividends throughout the project. A clean, compliant baseline establishes credibility with the owner, provides a defensible foundation for delay analysis, enables accurate earned value tracking, and streamlines monthly update submissions.

Consider engaging a third-party schedule review before submission. An independent set of eyes often catches issues that the development team has become blind to.