What hidden costs should I actually build a contingency for?

Short answer: The most common under-budgeted items are imported material shipping and customs
delays, mid-construction design changes, soil surprises, site security, waste removal, perimeter walls
and gates, landscaping and irrigation, generator or pressure-system upgrades, and owner-requested
scope changes.
Why it matters: None of these are exotic — they show up on most projects in some form. The buyers
who get surprised aren’t unlucky; they just didn’t plan for the gray areas.
What to check:
● Ask your builder what contingency percentage they recommend and why
● Get clarity on who absorbs cost from owner-requested changes mid-build

● Ask specifically about soil conditions on your lot before finalizing your budget
Bottom line: The goal isn’t to eliminate hidden costs — it’s to stop pretending they don’t exist and build
a realistic buffer around them from day one.