What are the two main approaches to construction estimating?

The two main approaches to construction estimating are top-down estimating and bottom-up estimating.

Top-down estimating involves starting from the large-scale project level and breaking it down into smaller components. This method often uses historical data and a set percentage or value based on similar past projects to estimate the total cost. It is beneficial when a quick estimate is required, or when detailed information about individual items is not readily available.

On the other hand, bottom-up estimating takes a more detailed approach by analyzing each component or activity of the project. Every item or task is estimated individually, and these estimates are then totaled to determine the overall project cost. This method, while more time-consuming, tends to be more accurate as it considers specific project details, quantities, and labor rates.

Both approaches serve different scenarios in estimating. Top-down is typically employed for initial project feasibility assessments, while bottom-up is used for comprehensive project planning when detailed project information is available. Understanding these two approaches equips estimators with the necessary strategies to address various estimating requirements effectively.