Every remodel has a moment of truth — usually about three days into demo — when something behind a wall turns out to be different from what anyone expected. Old wiring. Soft framing. A water line in a place no plan showed. These surprises aren't failures. They're the nature of working on a home that's been lived in. Good remodels plan for them. Here's how. Build a Real Contingency Into the Budget Plan for 10 to 20 percent of the project budget to sit untouched as contingency.