Most renovation professionals recommend setting aside 10 to 20 per cent of your total project budget as a contingency fund for unexpected costs. Older properties typically warrant a larger contingency, as hidden issues such as structural damage, outdated wiring, or asbestos are more likely to be uncovered once work begins. Starting with a detailed scope of work, obtaining multiple contractor quotes, and resisting the urge to cut the contingency budget are the most effective ways to stay financially protected throughout the project.