- As-Built vs. Design Drawings: What Sets Apart an As-Built from Others
- Why Contractors Need As-Built Drawings
- How As-Built Drawings Are Created
- Common Mistakes That Undermine As-Built Accuracy
- Design Drawings vs. Shop Drawings vs. As-Built Drawings
- As-Built Drawings Document What Has Actually Been Built
- FAQs
An as-built drawing shows the building as the construction team completed it, not as the original design intended. It records every change made during construction, such as relocated outlets and rerouted ductwork, making it the only drawing that accurately reflects the building’s final condition. Failure by contractors to produce an as-built drawing results in this documentation gap.
Usually, the discrepancy between design intent and actual construction is not small. The field conditions, the substitutions of materials, the coordination adjustments, and the changes demanded by the client all build up during the process of construction, and at the end of construction, the design drawings can become seriously outdated when compared to what actually is in the building. The as-built drawings are meant to eliminate this discrepancy.
As-built drawings are updated construction drawings that document the completed structure as it exists on site. They record every modification made during construction, including changes to dimensions, materials, equipment locations and building systems. Contractors require as-built drawings because design and shop drawings show the intended construction, while as-built drawings show what the project team actually installed.
As-Built vs. Design Drawings: What Sets Apart an As-Built from Others
Design drawings are those that show the design concept before any alteration due to construction or change orders. By contrast, shop drawing services add detailed fabrication and installation information for a particular trade based on the approved design. Unlike design drawings, teams prepare as-built drawings after construction and record every alteration, substitution, and deviation made during the project.
Why Contractors Need As-Built Drawings
- Facility management and maintenance — building operators need to know the actual location of MEP systems, not their originally designed location, to maintain them safely and efficiently.
- Future renovations — a renovation team working from outdated design drawings instead of as-builts risks cutting into a wall or ceiling without knowing what’s actually routed through it.
- Warranty and compliance documents — as-built drawings form an important part of construction documentation services and may support project handover, warranty claims, regulatory submissions and future reference.
- No repeated site surveying — accurate as-built drawings ensure that future project teams do not have to conduct another survey on existing site information.
How As-Built Drawings Are Created
The construction team usually begins the as-built drawing process by marking field changes on the original design drawings. Surveyors or laser scanning specialists then verify those redlines when necessary. Finally, the drafting team uses professional CAD drafting services to produce accurate CAD drawings that reflect verified field conditions rather than the original design with scattered notes.
Our guide to the Scan to BIM process explains how project teams convert laser-scanning data into coordinated models for documentation, renovation and facility management.
The verification step matters more than it might seem. The accuracy of the redlines depends entirely on the person recording the changes. When teams rush the markup process, they may omit important details or record inaccurate dimensions. A design team drafting up redlines into a finished as-built plan that does not have its own independent verification of areas of question to ensure accuracy in terms of field conditions could potentially generate an official-looking but inaccurate document.
Common Mistakes That Undermine As-Built Accuracy
- Treating redlines as final — converting field markups directly into as-built drawings without verifying uncertain areas against actual conditions.
- Waiting until project closeout to start — trying to reconstruct months of changes from memory at the end of a project produces far less accurate results than updating documentation as changes happen.
- Documenting only major changes — smaller field adjustments get skipped because they seem insignificant at the time, but can matter considerably during a future renovation.
Design Drawings vs. Shop Drawings vs. As-Built Drawings
| Drawing Type | Purpose | When It’s Used |
|---|---|---|
| Design Drawings | Represent the original design intent before construction | During the design and permitting stages, before construction begins |
| Shop Drawings | Add fabrication-level details for a specific trade | During construction, before contractors install that trade’s work |
| As-Built Drawings | Record the building’s actual final constructed condition | After construction, for handover, closeout and future reference |
As-Built Drawings Document What Has Actually Been Built
All buildings are changed slightly from design to reality, and an as-built drawing is the only way to document the differences. Omitting this process does not reduce the time necessary for the task; it simply moves the work required to determine what really exists onto someone else, typically in an even more undesirable time frame.
Need Accurate As-Built Drawings for a Completed Project?
Optimar Precon converts field redlines and survey data into clean, verified as-built drawings for architectural, structural and MEP systems. Contact us to discuss your project scope.
FAQs
Requirements vary by jurisdiction and project type, but most permitting agencies and building owners require project teams to submit as-built drawings during project closeout.
As-built drawings responsibility is usually specified in the construction contract. It could either be the general contractor, the subcontractor of his particular trade or even an independent CAD drafting team whose job would be to convert the field red lines into drawings.
These two types are usually interchangeable, although there are those who define the former as a design drawing that has incorporated all the changes made thus far, while the latter involves a check against the field condition using surveying and inspections and not just reports of changes.
The required accuracy depends on how the facility management team plans to use the drawing. If the team will rely on it for future maintenance, the drawing must accurately show the building’s dimensions and installed conditions.
Yes, this has become increasingly common. An as-built BIM model contains the same information as a 2D as-built drawing while preserving the model’s data for facility management systems to use.
Continual updating is always more accurate than doing reconstruction later when it is too late, and memories have faded.
