Most subcontracts include a sentence that does more damage than any other: the subcontractor shall perform its work in accordance with the contractor's project schedule, as updated from time to time.
That sentence makes the general contractor's schedule your commitment. The durations the GC's scheduler chose for your work, the dates your areas are supposed to be ready, and the logic that ties your work to everyone else's all become the standard you will be measured against. When the job runs late, the schedule decides who pays.
Electrical, mechanical and civil contractors carry more schedule risk than almost anyone on a project, because so much of the critical path runs through their work. Yet many never look at the GC's schedule in native form. They see a PDF of the bars that affect them, if that.
Here is what an electrical, mechanical or civil contractor working under a GC should check, and when. To you, your contract is the whole job. The GC's schedule is where that job gets won or lost.
When to review
Three moments matter most:
- Before signing, or before the baseline is accepted. This is when objections are cheapest. Once the owner accepts the GC's baseline and your subcontract ties you to it, changing your durations means asking someone to admit their accepted schedule was wrong.
- Every month, when the update comes out. Updates are where durations quietly get shorter and logic quietly changes.
- Whenever you are told to accelerate or resequence. That instruction should be compared to the schedule before you comply.
What to check
Your durations against your plan. Pull every activity for your scope and compare the duration to your estimate: the crew size and production rate you priced. A 40-day rough-in shown as 25 days is not a scheduling detail. It is a crew-size commitment you never agreed to.
How your work is broken down. If all of your rough-in on three floors is one activity, the schedule cannot show that floor 2 was handed over late. Ask for your work to be broken down by the same areas the GC uses for handovers.
Your access dates. The dates your areas become available are usually driven by other trades: structure, framing, ceiling grid, permanent power. Check what logic drives your start dates and whether it is realistic. An area-ready date with no real predecessor is a date nobody is responsible for.
Logic ties to the trades around you. Your work depends on inspections, other trades' completion and owner decisions. If those ties are missing, a late predecessor will not show as a delay to your work. It will show as you being late.
Float. Check whether your activities show float, and whether that float is real. Float on paper that depends on a predecessor finishing early is not float you can use.
Long-lead equipment and submittals. For electrical and mechanical subs, switchgear, panels, generators, air handlers and chillers often drive the job. Check that submittal, approval, fabrication and delivery are all modeled with the durations your vendors actually quoted.
What to do with what you find
Put it in writing, tied to activity IDs. A list that says "Activity E-2140 shows 25 working days; our bid assumed 40 working days at a 6-person crew" is something the GC's scheduler can act on and something that protects you later. A general complaint that the schedule is unrealistic is neither.
Then track it every month. Compare each update to the last one and to the baseline. Log every shortened duration, every changed tie and every slipped access date that affects your scope. That log is the foundation of any later time extension request, acceleration claim or defense against back charges.
When the schedule is already squeezing you
If durations are already being compressed, or your crews are being sent out of sequence, the same review becomes evidence. The comparison of updates shows what changed and when. A time impact analysis built on the GC's own schedule shows whether the change delayed your work, and by how much. Out-of-sequence work does not automatically mean critical path delay, so it is worth knowing honestly whether the time is supportable before a request goes in.
Where CPM Pros fits
CPM Pros supports electrical, mechanical, plumbing, fire protection and civil contractors working under a GC. We review the GC's Primavera P6 schedule from your side. We read the native file or the PDF, check your durations, access dates and logic against how your crews actually install, and give you a written list tied to activity IDs. We also track the monthly updates and build the fragnets and time impact analyses when a delay needs to be proven. Electrical contractors on large jobs use us exactly this way.
Send the GC schedule PDF or your contract, and we will send back a written quote, typically within 3 business days.