Set aside 10 to 15 percent of your total project cost as a contingency reserve for unforeseen discoveries. When walls open, hidden code violations emerge, or structural issues are found, contingency prevents budget overruns and bad decision-making. Most homeowners who skip contingency end up financing changes mid-project or cutting critical systems to stay on budget. Kingdom & Co. treats contingency as non-negotiable because project surprises are guaranteed, not optional, and contingency separates projects that finish on time from those that halt mid-construction waiting for funding.