As-built records document what was actually constructed, as distinct from what was designed: final routes of services, actual levels and dimensions, substituted products and materials, and the marked-up or re-drawn information that reflects them. Every building differs from its drawings; the as-built record is the honest account of how.
The family is wider than drawings. It includes red-line markups, schedules of substitutions and approved changes, test and commissioning certificates, manufacturer information for what was actually installed, and the operation and maintenance manuals. Under CDM 2015 the health and safety file carries the safety-critical part of this forward, and clients increasingly specify structured digital handover under ISO 19650 rather than boxes of PDFs.
The Building Safety Act raised the stakes. For higher-risk buildings the golden thread must carry an accurate as-built record, and gateway 3 asks directly whether what was built matches what was approved at gateway 2, with evidence. Changes made during construction have to be controlled and recorded when they happen, not recovered at the end.
The practical challenge is capture. Deviations happen daily and are forgotten weekly: the duct moved to miss a beam, the drainage run adjusted around an obstruction, the substituted fixing. An as-built drawn from memory months later is fiction with a title block. The cheapest reliable as-built evidence is the photograph taken as work proceeds, dated, located and filed somewhere searchable, especially for anything about to be covered up: buried services, filled trenches, closed ceilings and voids.
The record pays back for decades. Whoever operates, maintains, alters or eventually deconstructs the building depends on it, and the absence of reliable as-builts is priced into every future project as investigation, opening up and risk. Handing over a building without them is handing over a set of questions.
Construction Metric files dated, located site photos into a searchable record as the job runs; its Building Safety Act page explains how that supports the golden thread and gateway evidence.