Often, it's not until a project is complete that one determines its profitability. And profitability at the time of completion can vary significantly from expectations at the time of the bid. The ideal scenario is that a construction business owner can gauge profitability before the project even gets underway. Otherwise, you're not only losing money on jobs; you're putting your business at risk.

Still, a common misconception is that when profits are lost, the loss occurs after the project is started and is due to circumstances beyond one's control. The reality is that when contractors lose money, the loss is most often borne out of the cost-estimation process.

To help you more effectively navigate this process, here are 10 of the most common cost-estimating mistakes putting your business at risk, and what to do about them:

1. Lack of transparency. The estimate should provide a top-level view of the project as well as each line item's most granular details and their associated costs. This way, you eliminate the black-box approach, and anyone can easily understand the process for determining cost, regardless of his or her level of experience. Transparency also invites collaboration and the sharing of best practices throughout the company.

2. Last-minute changes. Late changes result in simple mistakes such as forgotten line items and formula errors from cutting and pasting. Such errors can quickly turn a profitable project into a loss. Accurate cost-estimation systems with built-in formulas and assembly libraries, however, can eliminate most, if not all, of these errors.