Which document establishes the actual start date from which the project duration is calculated?

The Notice to Proceed is the document that establishes the actual start date for a construction project. This notice is issued by the project owner or the owner's representative to the contractor, instructing them to commence work on the project. It signifies the formal authorization for the contractor to start mobilizing resources and executing the work as outlined in the contract.

The notice is crucial because it not only signifies the beginning of the project but also marks the point from which the contractual timeframes and schedules are tracked. Without this document, it would be challenging to determine when the project officially begins, which is essential for managing timelines, accountability, and addressing any delays effectively.

In contrast, the Certificate of Substantial Completion refers to the point at which the project is sufficiently complete for the owner to occupy or utilize, but it does not establish the start date. A Stop Work Notice is issued to halt work due to various reasons but does not relate to the commencement of work. A Change Directive is used to modify the work or contract terms but again does not indicate when the project starts. Thus, the Notice to Proceed is critical for establishing the official start date that governs the project duration.