Practical completion is the contractual milestone at which the works are complete enough for the employer to take over and use them, even though minor items may remain. Few standard forms define it exhaustively; the working test in English practice is that the works are free from defects other than trivial ones that do not prevent the intended use. The judgement is the certifier’s, and honest minds can differ at the margin.
Enormous consequences hang on the date. Liquidated damages stop accruing. Half the retention falls due for release. The risk of loss or damage, and with it the insurance obligation, passes to the employer. Possession returns, the rectification period begins, and the clock starts on the final account processes. Because one certificate moves all of that at once, the date is argued more than almost any other on a project.
JCT contracts have the certifier issue a practical completion certificate, with sectional completion where the works are divided into sections and partial possession where the employer takes part of the works early, each carrying proportionate consequences for damages and retention. NEC takes a different route: Completion is a defined term, tested against what the Scope says must be done by Completion, and the Project Manager certifies it within a week of it occurring. Where the contract lists documentation, test certificates or training as completion requirements, missing paperwork can hold the date back as effectively as missing work.
The pressure around practical completion is usually commercial. Employers facing funding, letting or occupation deadlines want the building; contractors facing liquidated damages want the certificate. Beneficial occupation, where the employer moves in without a certificate, blurs the line and generates arguments about whether taking over the works amounted to completion in fact.
What settles those arguments is evidence of the state of the works at the time: inspection records, the outstanding works and snag lists as they stood, photographs, commissioning results and the correspondence around occupation. The party that can show what was and was not complete on the day usually wins the argument about what the day meant.
A daily photographic record shows the state of the works on any date you later need to prove: see a sample diary Construction Metric built automatically.