As-Built Documentation
Drawings that show what was actually built, not just what was designed.
Quick Answer
As-built documentation is the set of drawings and records that show a building as it was actually constructed, including deviations from the original design such as field changes and relocated systems. Contractors mark up the drawings during construction and deliver the updated set at closeout. Owners use them for maintenance, renovations, and future projects.
The Full Picture
No building is built exactly as drawn. Conflicts are resolved in the field, products are substituted, and routing is adjusted around obstructions. As-built documentation captures those differences so the owner has an accurate record of what is in the walls, above the ceilings, and below grade.
In practice the contractor and its subcontractors keep a marked-up set of drawings during construction, noting changes from the contract documents, often referred to as redlines. At closeout those markups are transferred into a clean set, either by the contractor or by the design team, and delivered to the owner. Terminology varies: some contracts distinguish contractor-prepared as-builts from record drawings prepared by the architect or engineer from the contractor's markups, while others use the terms interchangeably. The contract documents define what is required.
Accuracy is the recurring challenge. Markups made late or from memory can miss concealed work, especially underground utilities, which is why some owners require survey or scanning of critical elements before they are covered. Digital methods such as laser scanning and updated BIM models are increasingly used to support the record, though requirements vary by project.
Although as-builts are delivered after construction, the requirements for them are set in the contract and the specifications. Preconstruction teams read those requirements so that subcontractors price the markup effort, and so the expected format, level of detail, and responsibility for the final record set are clear from the start.
Real Examples
Common Misconceptions
People assume: As-built drawings are the same as the construction documents used for bidding.
Actually: Construction documents show the design intent. As-builts show what was actually installed, including field deviations, change order work, and substitutions.
People assume: As-builts are guaranteed to be perfectly accurate.
Actually: They are only as accurate as the field markups and verification behind them. Contracts often limit reliance on them, and concealed conditions may still need to be verified.
Frequently Asked Questions
What is the difference between as-built and record drawings?
Usage varies by contract. Often as-builts are contractor markups of field conditions, while record drawings are the finished set prepared by the design team from those markups. Always check how your contract defines them.
Who is responsible for as-built drawings?
Typically the general contractor, with each subcontractor contributing markups for their work. The contract may assign final drafting to the contractor or the design team.
When are as-builts delivered?
Usually at or before project closeout. Contracts often tie final payment or retainage release to delivering acceptable as-built documentation.
Why do owners need as-built drawings?
They support operations, maintenance, repairs, renovations, and additions. Accurate records reduce the need for exploratory demolition and help locate hidden systems.
Can BIM or laser scanning produce as-builts?
Yes, they can support or verify the record. Many projects update the model or scan completed work, though the contract determines what format and accuracy are required.