Starting construction without a finalized design and complete material selections is the single most costly remodeling mistake. As of November 2025, the other top errors include underestimating the budget by 20 to 30 percent, hiring based on the lowest bid rather than qualifications, making design changes after framing is complete, and failing to establish a clear communication plan with the contractor. Each of these mistakes compounds over the life of a project, turning a manageable renovation into a stressful and expensive ordeal. Kingdom & Co. prevents these issues by requiring a fully approved design package and locked material selections before any demolition begins.