Change Orders That Don't Blow Your Construction Schedule
A change order that goes unsigned for two weeks while a GC and owner negotiate price is a two-week schedule hit on whatever critical-path trade is waiting. Authorize work the day you identify the change, settle the price separately, and check your CPM float before you do either.
How Does a Change Order Push Your Completion Date?
The schedule slips in the gap between when a change gets identified and when a sub starts the work. That gap is where the damage happens. Control the gap and you control the date.
Construction schedules run on a critical path: the chain of dependent tasks that sets the earliest possible finish date. Activities off that chain have float, meaning they can absorb a delay without moving the end date. Critical path work has no float. Lose a day there and it goes straight onto the completion date.
Change orders hit critical path work more often than most GCs expect. An RFI resolves late and triggers a structural revision. An owner adds a bathroom in the middle of rough plumbing. A scope clarification shifts a sequence two trades are waiting on. When that happens, how fast you move the CO through the system determines whether the date holds.
The single biggest controllable factor is authorization speed. The most common version of this problem I see is a manageable change sitting unsigned for a week while the GC and owner go back and forth on unit prices. The sub is ready. The materials are on hand. The authorization is the bottleneck. A sub sitting idle while paperwork circulates is a sub billing standby time on the next change request.
What Happens If You Miss the 21-Day AIA Notice Window?
Under AIA A201-2017 Section 15.1.3, a party must give written notice of a claim for additional time within 21 days of when they first recognize the condition giving rise to that claim. Miss that window and the time extension claim may be waived, regardless of how legitimate the delay is.
This cuts both ways. If a CO is going to push your schedule, file written notice before those 21 days close. If a sub claims the CO blew their schedule, check whether they gave you timely written notice under your subcontract. Some subcontracts tighten the window below 21 days. Some require a preliminary schedule impact statement alongside the notice. Read those provisions before the project starts, when you can still negotiate the language.
The notice is a document that preserves your options. You file it, keep working, and sort out the time credit during the price negotiation. Skipping it because the project relationship feels solid is the routine mistake. The relationship feels solid until something expensive happens.
If your subcontracts do not have explicit notice provisions, the conversation with your attorney about adding standard language costs less than one disputed delay claim.
How Do You Keep Work Moving While Negotiating Change Order Price?
Most commercial contracts include a Construction Change Directive. The AIA G714 form is the standard vehicle. A CCD lets an owner authorize work to proceed on a time-and-materials basis while a fixed price is still being negotiated. The sub tracks hours and materials. The parties agree on a fixed price later. Work does not stop.
Here is how the two authorization paths compare:
| Standard CO | CCD (AIA G714) | |
|---|---|---|
| Price settled | Before work starts | After work completes |
| Work starts | After signature | Same day as directive |
| Schedule risk | High if price dispute stalls | Low: work proceeds |
| Cost risk | Low: fixed price agreed | Moderate: T&M exposure |
| Best use | Simple, non-urgent scope | Critical-path changes with open pricing |
Using a CCD well requires a current, clean rate sheet from the sub. T&M billing at undocumented or inflated rates turns into a fight in the middle of a schedule crunch. Pull the sub's prevailing rate sheet at prequalification, before the job starts, and confirm it is current and signed. Running that verification before the project clock starts is what a platform like SubSource is built for: getting prequalification documents in hand before a CO request puts everyone under pressure.
Put the work authorization in writing the same day you give verbal direction. A verbal go-ahead followed by a written CCD that afternoon is a defensible record. On large scope items, confirm the CCD covers the full scope the sub needs to mobilize. A sub who mobilizes and finds the authorization was narrower than the work will stop again. Close that gap in the directive itself.
How Do Material Lead Times Affect Change Order Scheduling?
Labor is visible. A sub is on site or not. Material lead times are invisible until a trade shows up and there is nothing to install.
A change order that looks labor-light can carry a long procurement tail. Adding a specialty door or swapping an HVAC unit triggers procurement. So does running additional conduit to a location that takes fittings not already on site. A four-week lead time on specialty materials means the CO adds at least four weeks to that scope, regardless of how fast the paperwork gets signed.
Ask for the material procurement lead time as part of the CO request, alongside the price. A complete CO submission from a sub should include:
- Scope description and affected schedule activities
- Labor hours and crew size
- Material items with quantities
- Lead time on anything that cannot be sourced same-day or same-week
- Which CPM activity the material feeds
If the lead time hits a critical-path activity, authorize the material procurement separately and immediately. Most standard contracts allow a partial authorization for procurement for exactly this reason.
Keep a one-page procurement log for active COs. The columns that matter: scope description, material item, lead time, order date, expected delivery, and which schedule activity it feeds. Update it weekly. It catches a delivery problem before the trade mobilizes to a site with nothing to start on.
How Do You Check Float Before Authorizing a Change Order?
Float is the schedule buffer between non-critical activities and the critical path. Change orders consume float quietly. Individually, each CO looks harmless. The cumulative effect is the threat.
Run a float check on every CO before you authorize it. Open the CPM schedule, find the activity the CO touches, and note the total float on that chain. If the float goes negative, the CO hits the critical path and the 21-day notice clock is running. If the float gets thin but stays positive, flag that chain for the next CO that touches it.
This is not a full delay analysis. It takes ten minutes with someone who knows the schedule. The difference is catching a schedule problem while there is still time to respond, rather than discovering it in the final month of the job when the only option left is acceleration cost.
What If an Owner Directs You Verbally to Proceed?
Send a same-day email confirming what was authorized: the scope, the basis (T&M or fixed price), and that formal documentation will follow. That email is a contemporaneous record of the direction. On a large scope item, get your contract attorney involved before you proceed on undocumented authorization.
Does a Zero-Cost Change Order Still Need a Schedule Review?
Yes. A no-cost CO that changes a detail, a sequence, or a material spec can still consume float or hit the critical path. Cost and time are independent variables. Run the float check regardless of the dollar amount.
What If a Sub Claims the CO Blew Their Schedule but Never Gave Written Notice?
Check your subcontract's notice provision first. If the sub failed to give timely written notice as required, the claim may be contractually waived. Document your review of the notice provision and the sub's failure to comply. Even so, understand whether the CO affected your own critical path. A delay that moves your schedule has downstream consequences regardless of the sub's claim status.
On the next CO request you receive, before you respond to the price, open the schedule and find the activity it touches. Check the float on that chain. If it is under five days, treat it as a potential critical path event and prepare the notice documentation before you authorize anything.