Common DIY mistakes that hurt home resale value include poor planning, inaccurate measurements, and scope creep extending projects far beyond initial estimates. These errors lead to unfinished work, visible defects, or delays that frustrate buyers. Hidden issues uncovered during projects—like rot or faulty wiring—can cause costly pivots or failed inspections if mishandled. Avoid these by locking your renovation scope early, properly measuring, and staging to highlight completed improvements effectively.