As built drawings are produced at the least convenient moment: the project is finishing, budgets are spent and attention has moved on. They are also the drawings the owner will rely on for every future alteration, which makes the usual level of care a false economy.
What they are, and what they are not
Record drawings show what was actually built, incorporating changes made during construction. They are not the tender set with a new title, and they are not a survey. The distinction matters when someone later designs against them.
Be explicit about the basis: whether the set reflects contractor markups, verified site measurement, or a mixture. Anyone using them later needs to know how much to trust them.
Where the information comes from
Typically from several sources of varying reliability: contractor marked up drawings, approved change orders and instructions, RFI responses that altered the work, shop drawings for fabricated elements, and site verification. The quality of the result depends almost entirely on how well these were captured during construction rather than reconstructed after.
The habit that makes it manageable
Update progressively. Capturing changes as they are instructed, rather than assembling everything at handover, is the difference between a straightforward exercise and an archaeological one. By the end of a long project nobody reliably remembers why a wall moved eighteen months ago.
Where a contractor is required to maintain marked up drawings, check them periodically rather than at the end. Markups that have not been kept up are usually discovered too late to fix properly.
What matters most to include
- Concealed services routes, which are the most valuable and most often omitted information
- Actual equipment installed, with model references rather than specified equivalents
- Structural changes and any additional support installed
- Fire stopping locations and rated assembly changes
- Valve, isolator and access panel positions
- Any dimensional deviation from the documented design
Format for the long term
Provide both native files and PDFs, and make sure the PDFs are legible standalone since they will outlive access to the software. Name and index the set clearly. A folder of files named with the contractor's internal codes is nearly useless to an owner in ten years.
Where a model is handed over, be clear about what it represents and to what level of accuracy, otherwise a future designer will assume more precision than exists.
Agree the scope early
As built requirements should be settled at appointment, not at completion: who produces them, from what sources, to what standard, and in what format. Left undefined, they are produced grudgingly by whoever has least standing to refuse, and the quality shows.