AS-BUILT DRAWINGS: WHAT THEY ARE AND WHEN YOUR PROJECT NEEDS THEM

As-built drawings show a building the way it was actually constructed, not the way it was designed on paper. The two rarely match. During construction, contractors move outlets, shift walls by a few inches, reroute pipes around unexpected obstacles, and swap materials. Every change makes the original plans a little less accurate. As-built drawings capture the final state of the building with all these field changes included.

Here is a typical situation. An Architect takes on the renovation of an office building from the 1970s. The owner hands over a folder of faded paper plans and says this is all the documentation there is. Before any design work starts, someone has to establish what the building really looks like today: where the walls, pipes, and wiring actually are. That is the job of as-built drawings.

In this article, we explain what as-built drawings are, how they differ from design drawings, what a complete set includes, and how to get accurate as-builts even if all you have is a box of old blueprints.

#1. What Are As-Built Drawings?

An as-built drawing is a revised set of plans that reflects the exact state of a finished building or space. It records the real dimensions, locations, and materials of every element: walls, doors, windows, plumbing, electrical wiring, HVAC, and structural components.

During construction, the contractor usually marks all deviations from the design set right on the working drawings, often in red pen. These marked-up sheets are called red-lines. After the project is finished, a drafter transfers the red-lines into a clean, accurate final set. That final set is the as-built documentation of the building.

#2. As-Built Drawings vs Design Drawings

Design drawings show intent: what the team plans to build. As-built drawings show the result: what was actually built. The difference sounds small, but for anyone working with an existing building it is critical. A wall that sits a foot away from where the plan shows it can ruin a furniture layout, a millwork installation, or a renovation estimate.

Key differences in short:

• Timing. Design drawings are created before construction, as-builts after it.
• Content. As-builts include every approved change order and field adjustment.
• Purpose. Design drawings guide the builders. As-builts serve everyone who deals with the building afterwards: owners, facility managers, and future designers.

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#3. What a Complete Set of As-Built Drawings Includes

The scope depends on the building and the tasks ahead, but a full set usually contains:

• floor plans with verified dimensions;
• elevations and sections;
• plumbing and drainage layouts as installed;
• electrical plans with the real positions of outlets, switches, and panels;
• HVAC layouts;
• notes on materials and on deviations from the original design.

The result is delivered in two formats: PDF for records and approvals, and editable DWG or DXF files for future work in CAD software.

#4. Who Needs As-Built Drawings and When

Property owners and facility managers. With accurate as-builts, any repair starts with opening a file instead of opening a wall. Maintenance teams see where every pipe and cable runs.

Architects and interior designers. Renovation and remodeling projects need a reliable base plan. Working from outdated drawings leads to wrong estimates and redesigns halfway through the project.

Contractors. Many jurisdictions require as-built documentation at project closeout. Clean, professional as-builts also make a good impression on the client at handover.

Buyers and sellers of real estate. Complete documentation raises trust and speeds up due diligence in a transaction.

#5. How As-Built Drawings Are Created

There are three common ways to produce as-builts, and they are often combined.

Field measurements. A specialist measures the space with a laser measure and sketches the layout, then a drafter turns the notes into CAD drawings. This works well for apartments, offices, and small commercial spaces.

Laser scanning. For large or complex buildings, a 3D scanner captures the geometry in a single pass. The resulting point cloud becomes the base for drawings or a BIM model. We described this process in our article on the point cloud to BIM workflow.

Redrawing from existing documentation. If old paper plans or scans exist, the fastest route is to digitize them and update the drawings with the known changes. This is what our CAD conversion services do: we redraw paper drawings, scans, and PDFs into accurate DWG files by hand, so the geometry and dimensions stay reliable. Read also about the 4 main options of CAD digitizing.

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Need accurate as-built documentation for your property or project? Contact ArchiCGI, send over your scans, sketches, or old blueprints, and get a clean, editable set of drawings you can rely on.

Catherine Paul
Content Writer, Editor at ArchiCGI

Catherine is a content writer and editor. In her articles, she explains how CGI is transforming the world of architecture and design. Outside of office, she enjoys yoga, travelling, and watching horrors.

As-Built Drawings FAQ