A small design change can add $100,000 to a project. The difference in the material price may explain only a fraction of it.
Consider a hypothetical switch to a different floor finish late in a project. The replacement costs slightly more, but it also takes longer to arrive. If the space cannot be completed without it, and the schedule has no room to absorb the wait, that decision can delay handover and extend the cost of keeping the site running.
Look beyond the unit rate
The initial price captures what the team is buying. It does not necessarily capture what the change does to installation, sequencing, or the completion date. Those effects depend on the actual project: what has already been ordered, which trades follow, and whether the affected work sits on the critical path.
For illustration, a $30,000 increase in direct costs plus 14 additional days of site costs at $5,000 a day would total $100,000. Those are hypothetical figures, not a benchmark. The point is to examine the relationship between the price and the delay, then use the project's own evidence to test whether either applies.
A more expensive material may still be the right choice. What matters is that the team can evaluate the full consequence before committing.
Bring the decisions together earlier
The Suffolk-MIT white paper, Construction in the Age of AI, makes a useful case for connecting design options, quantity takeoff, estimating, and scheduling. Considering those inputs together gives teams a better opportunity to understand cost and delivery consequences while the design is still changing.
In practice, that means reviewing a proposed finish against its quantity, supplier quotation, lead time, installation requirements, and place in the programme. A price comparison becomes much more useful when everyone is looking at the same scope and the same timing assumptions.
Make the calculation reviewable
The paper also calls for transparent and auditable AI, supported by secure data practices and accountable professional judgment. If AI helps assess a change, the team needs to see which quantities and prices were used, where those figures came from, and how the assumed delivery date affects the schedule.
A useful review should make it possible to challenge each input. Is that lead time current? Has the extra site cost already been counted elsewhere? Can the work be resequenced? Which costs are confirmed, and which still depend on a supplier or the project team?
This is the kind of clarity we want estimating to provide. A decision is easier to evaluate when its cost, schedule implications, and remaining uncertainties are visible before the money is committed.