How to update a subcontractor schedule when dates change

Separate the event from the forecast

The GC moves site access. A reviewer returns comments late. A supplier revises a ship date. Record the event and its date first, then update the affected dependency path. Do not overwrite the original baseline; otherwise the team loses the ability to explain why the forecast moved.

Distinguish an actual date, a committed date, and a planning forecast. Actual means the event happened. Committed means another party accepted a date. Forecast means the team currently expects it. These can be different on the same job.

• Keep a short change note with source and date.
• Preserve the prior milestone for comparison.
• Label unconfirmed dates as forecasts.

Trace the effect across the plan

Move the changed milestone or activity and review its successors. A late approval may push purchasing and production; delayed site access may create storage needs without changing fabrication. The effect depends on the links and available float, not on a rule that every date moves by the same number of days.

Check shared resources across other jobs. A crew displaced by one project may be available for another, while a delayed fabrication slot may collide with a committed package. A project update is incomplete if it creates a portfolio conflict.

• Inspect downstream handoffs and near-term capacity.
• Check whether a date is fixed by contract or can be negotiated.
• Do not automatically shift unrelated work.

Choose and communicate a response

Prepare realistic options: resequence, split delivery, add capacity, expedite an item, or revise a commitment. State the cost and assumptions for each. Ask the appropriate party to decide by a useful deadline, then update the schedule to match the accepted path.

A concise notice can say: the event, affected scope, former and current forecast, decision required, and date by which the decision matters. Contractual notice requirements vary by project and should be handled separately from the working schedule.

• Assign an owner to each recovery action.
• Avoid presenting an unapproved option as the new plan.
• Tell field and shop teams which dates actually changed.

Worked example

A drywall subcontractor loses access to two floors for one week, but material and crew are already booked. The schedule update should show the floor-specific access change, the crew's available alternatives, and any impact on follow-on taping and finishing. It may be possible to work another area rather than move the entire job.

If the alternate area is not released, the plan remains conditional. The PM should request the area decision before remobilization becomes the only option.

• Model by area when access differs.
• Show a conditional recovery path until it is approved.

Keep a small change record

For each material change, record the event date, source, affected area, former forecast, new forecast, and open decisions. A short note linked to the schedule is enough for routine coordination. Do not let the note become a substitute for any contractual notice required by the project.

Compare recovery options against real capacity. Adding a weekend shift can accelerate production only if material, drawings, equipment, and supervision are available. Splitting a delivery can help an early area while increasing trucking or handling. Make these trade-offs explicit before promising a new date.

After a decision, communicate one accepted sequence to the GC, shop, and field. A schedule issue should carry a date and revision label. If the recipient is working from another version, even a technically correct update may not change the work.

Update checklist

After the decision, issue one current forecast and archive the prior one. A schedule loses authority when the shop, field, and GC circulate different versions with no clear status.

• What event changed?
• Which dependencies and other jobs are affected?
• Which dates are actual, committed, or forecast?
• Who approved the response?
• Who needs the revised plan?

Common questions