certificate of substantial completion. Document verified by an architect, engineer, or owner of a construction project that the project is substantially complete and is approved for payment by the general contractor on the date of final payment.Click to see full answer. In respect to this, who issues the certificate of substantial completion on the construction project?When a project reaches this stage, the prime contractor usually wants a Certificate of Substantial Completion by the contract administration. This certification often includes a punch list of small items that still need finishing and its corresponding timeline to complete them.Secondly, how is substantial completion defined? Substantial Completion refers to a stage of a construction or building project or a designated portion of the project that is sufficiently complete, in accordance with the construction contract documents, so that the owner may use or occupy the building project or designated portion thereof for the intended purpose. Also know, who signs certificate of substantial completion? In many cases, the contractor and owner, including engineers, architects, or any other party, would sign the certificate, creating the date of the project completion. When a third party has produced a certificate of substantial completion, one of the key milestones have been reached according to the contract terms.Why is substantial completion important?The date of substantial completion is extremely important, because it determines the date that a contractor is no longer fully liable for delayed completion or for minor incomplete details. After substantial completion, the owner again becomes responsible for the property, i.e., security, utilities, etc.