10 common causes of construction cost overruns and how to reduce them

1. Incomplete or uncoordinated design

Starting construction while dimensions, levels, structure or building services are still being resolved increases the likelihood of changes and demolition. Early coordination reduces expensive field decisions.

2. Poorly defined scope

When contract inclusions are unclear, disputes arise over extras, supplies and responsibilities. A measurable scope with explicit exclusions improves control.

3. Unreliable quantities

Takeoff or budgeting errors lead to shortages and unplanned purchases. Quantities should be based on current drawings and updated when design changes.

4. Owner changes during construction

Changing finishes, layouts or specifications can affect materials already purchased and work already completed. Each change should be evaluated for cost and schedule before approval.

5. Urgent procurement

Poor planning reduces the ability to compare suppliers, negotiate and verify specifications. Buying under pressure usually increases price and error risk.

6. Rework caused by quality or coordination issues

Demolishing and rebuilding consumes material, labor and time. Checks before concrete pours, wall closures and finishes can prevent rework.

7. Low productivity

Uncoordinated crews, unavailable work fronts, insufficient equipment or waiting for materials create indirect cost. Scheduling should be tied to realistic resources.

8. Weak control of extras

Small extras can accumulate quickly. Each should have a description, justification, quantity, value and approval before execution whenever possible.

9. Underestimated logistics

Difficult access, internal hauling, limited storage or time restrictions can affect productivity. These conditions should be included in the budget from the beginning.

10. No contingency allowance

Every project has uncertainty. A reasoned contingency helps absorb unforeseen events without confusing them with budgeting errors or scope changes.