What document must include signatures from the architect, contractor, and owner to be valid?

The Certificate of Substantial Completion is a significant document in the construction process, marking the point at which the project has progressed sufficiently to be occupied or used for its intended purpose, yet not fully completed. For this document to be valid, it requires the signatures of the architect, contractor, and owner.

The inclusion of these signatures serves several purposes. First, it indicates that all parties involved in the construction have agreed that the project has reached this critical milestone. Secondly, it establishes a consensus on the state of completion, which is essential for triggering subsequent actions, such as the start of warranties and the beginning of the owner's responsibilities for maintenance.

The other options, while important in their contexts, do not require signatures from all three parties in the same way. The Final Acceptance Form generally signals the owner’s acceptance of the completed work but may not need all signatures. The Construction Agreement outlines the terms of the project but is signed at the outset. The Completion Affidavit attests to completion for the purposes of various legal and financial matters but does not typically require the same level of consensus among all parties involved.