What is the main reason a contractor should be cautious about starting work without a complete bid?

The primary reason a contractor should exercise caution when starting work without a complete bid is that it can lead to financial losses if additional materials are needed. A complete bid encompasses a thorough assessment of all project costs, including labor, materials, overhead, and profit margin. By not having a complete and accurate bid, a contractor risks underestimating the materials required for the project, which could lead to unexpected expenses. These unforeseen costs can severely impact the contractor's budget and overall profitability, making it crucial to ensure that all aspects of the project are adequately considered before commencing work.

While clients requesting additional work can be a concern, it stems from the initial lack of a solid bid framework. Competition among contractors can influence project dynamics, but it is not a direct financial risk like the potential for unforeseen material costs. Project timelines can be affected by several factors, but the most immediate risk without a complete bid remains the financial implications.