Ask any commercial owner where the budget went and you will hear about change orders. But change orders are not random — they cluster in predictable engineering coordination failures. Here are the traps, and how to avoid each one.
Trap 1: The incomplete geotechnical story
The soils report recommended drilled piers. The structural engineer designed for them. Then the drill rig hits rock at half the expected depth — or never finds bearing — and the foundation system gets redesigned mid-construction. The fix is not luck; it is investigation scope. On variable sites, the cheapest money in the project is additional borings before design. Every boring you skip becomes a change order with a 10x multiplier.
Trap 2: MEP routing discovered in the field
The mechanical contractor arrives to find the structural beams exactly where the ductwork needs to go. Coring, rerouting, soffits, and redesign follow — all at field-labor rates. Prevention is a coordinated BIM model or, at minimum, overlaid 2D coordination drawings reviewed in a real coordination meeting before permit. The coordination meeting costs a few thousand dollars. The field conflict costs tens of thousands.
Trap 3: The equipment that does not fit
The specified rooftop unit arrives and the curb does not match, the electrical service is undersized for the actual MCA, or the plumbing fixture rough-ins miss the architectural layout. Equipment submittals must be reviewed against the structural and electrical design — not just the mechanical schedule. Late equipment selections are the number-one generator of MEP change orders.
Trap 4: Unforeseen conditions in renovations
Open the wall and find: no insulation, undersized framing, asbestos, or a structural system nothing like the drawings suggested. Renovation contingencies should run 15-20% (versus 5-10% for new construction), and exploratory demolition before final design converts unknowns into knowns. The exploratory openings cost a few thousand; the surprise costs fifty.
Trap 5: Code interpretations discovered at permit
The plan checker reads the energy code differently than your team did. The fire marshal wants a second stair. The health department reclassifies the occupancy. Pre-submittal conferences exist precisely to surface these interpretations before the drawings are final. The owners who skip them pay in redesign cycles.
The owner's prevention checklist
- Fund the geotechnical investigation properly — it is the cheapest risk reduction available
- Require a coordination meeting with sign-off before permit submittal
- Lock equipment selections before MEP design completes
- Carry renovation contingencies at 15-20%
- Hold pre-submittal conferences with every reviewing agency
- Track change orders by cause — the pattern tells you which process failed
Change orders are a project management output, not an act of nature. The owners who treat them as data — tracking causes, fixing processes — see them shrink project after project. The engineering is rarely the problem. The coordination almost always is.