New Zealand Structures & Investments Ltd v McKenzie - [1979] 1 NZLR 515

Building contracts, engineers and architects — Authority of Engineer — Variations — Extension of time — Fixed price agreement signed on NZSS form 623 — Owner's Engineer and Engineer's Representative authorised extras increasing cost — Whether delegation to Representative valid — Whether extras validly authorised — Whether Engineer can grant extension of time after completion date — Whether completion certificate once issued can be withdrawn — Whether certificate final.