Substantial completion is a critical milestone defined in the construction contract. It marks the stage when the project is sufficiently complete, in accordance with the contract documents, so that the owner can occupy or utilize the work for its intended purpose. The architect is typically responsible for inspecting the work and issuing a Certificate of Substantial Completion. This certificate formally establishes the date of substantial completion, which is crucial as it often triggers the start of warranty periods, the release of the majority of the retainage to the contractor, and transfers responsibility for utilities and insurance to the owner.

A. The project is 50% complete: This is a progress milestone for payment but does not signify that the project is ready for use or occupancy.

C. All punch list items have been finished: This defines "final completion," which occurs after substantial completion. The punch list is created at the time of substantial completion.

D. The contractor has been paid in full: Final payment, including the final portion of retainage, is made after final completion, not substantial completion.

1. American Institute of Architects (AIA) Document A201-2017, General Conditions of the Contract for Construction.

Section 9.8.1: Defines Substantial Completion as "the stage in the progress of the Work when the Work or designated portion thereof is sufficiently complete in accordance with the Contract Documents so that the Owner can occupy or utilize the Work for its intended use."

2. The American Institute of Architects, The Architect's Handbook of Professional Practice, 15th Edition. Wiley, 2013.

Chapter 10.5, "Project Closeout," page 758: "Substantial completion is the point at which the project is sufficiently complete to be occupied or used for its intended purpose... The date of substantial completion is a very important milestone in the project, as it marks the end of the construction period and the beginning of the warranty period."

3. Glower, C. & Glower, S. (2021). The Architect's Legal Handbook (10th ed.). Routledge.

Chapter 10, "The Building Contract," Section 10.5.3, "Completion": This section distinguishes between practical completion (a UK term analogous to substantial completion) and final completion, clarifying that the former is about the building being ready for its intended use, even with minor defects outstanding. (DOI: https://doi.org/10.4324/9781003053957)