If you are planning a renovation, ADU, or commercial buildout in Los Angeles, you have probably run into both terms: CAD drawings and as-built drawings. They sound similar, and both involve technical floor plans, but they serve very different purposes in the permitting and construction process. Confusing the two can slow down a LADBS permit application or lead to costly rework once a project is underway.
This guide breaks down what each type of drawing actually is, how they are used on Los Angeles projects, and how to know which one your project needs.
What Are CAD Drawings?
CAD stands for computer-aided design. A CAD drawing is any technical drawing created digitally using software such as AutoCAD or Revit, rather than by hand on a drafting table. CAD drawings can represent almost anything: a proposed design, a structural layout, an MEP (mechanical, electrical, plumbing) plan, or a record of existing conditions.
In other words, “CAD” describes the format and tool used to produce a drawing, not what the drawing depicts. A CAD drawing could show a brand new design that has never been built, or it could document a building exactly as it stands today.
How CAD Drawings Are Used in Los Angeles Construction Projects
On most Los Angeles projects, CAD drawings appear at nearly every stage: initial design concepts, structural calculations submitted to LADBS, MEP coordination between contractors, and final as-built documentation. Architects and engineers rely on CAD files because they are precise, easy to revise, and compatible with the digital submission requirements that LADBS now uses for most permit types.
What Are As-Built Drawings?
An as-built drawing is a specific type of CAD drawing that documents a structure exactly as it currently exists, measured directly from the field rather than pulled from old blueprints or memory. As-built drawings capture the real dimensions, wall locations, window and door placements, and structural elements of a building as it stands today, including any unpermitted changes made over the years.
Unlike a general CAD drawing, an as-built drawing is not a design proposal. It is a factual record created through on-site laser measurement and field verification, then converted into a clean CAD file that matches reality down to the inch.
Why LADBS Requires As-Built Drawings for Permits
The Los Angeles Department of Building and Safety frequently requires as-built drawings before it will process a permit application for a remodel, addition, or ADU, especially when no existing plans are on file or when the property has been altered without permits over the years. LADBS uses these drawings to confirm the true starting condition of the building before evaluating any proposed changes. Without an accurate as-built set, a permit application can be delayed or rejected outright. You can review LADBS submittal requirements directly on their official site.
Key Differences Between CAD Drawings and As-Built Drawings
Purpose and Timing
A general CAD drawing is often produced during the design phase, before construction begins, to communicate what a project will look like once built. An as-built drawing is produced after the fact, either to document a building’s current condition before a remodel or to record the final result of a completed project for the permanent file.
Accuracy and Field Verification
Design-phase CAD drawings are based on architectural intent and may shift as the design evolves. As-built drawings, by contrast, are built entirely from field measurements, often collected with 3D laser scanning, so every dimension reflects the physical reality of the structure rather than what was originally planned.
Use Cases: New Construction vs Renovations
CAD drawings dominate new construction, where there is no existing building to measure and the entire design is created from scratch. As-built drawings become essential the moment an existing structure is involved, which covers the vast majority of remodels, additions, ADU conversions, and commercial tenant improvements across Los Angeles.
Comparison Table
| Aspect | CAD Drawings (General) | As-Built Drawings |
|---|---|---|
| Represents | Proposed design or any digital plan | Existing, field-verified conditions |
| Created When | Before or during construction | Before a remodel or after completion |
| Data Source | Architectural design intent | On-site laser measurement |
| Required by LADBS For | New construction plan sets | Remodels, ADUs, additions with no existing plans |
| Accuracy Standard | Design-driven, subject to revision | Matches physical structure exactly |
When Do You Need Each Type of Drawing?
If you are designing a brand new building on a vacant Los Angeles lot, your architect will work almost entirely in general CAD drawings, since there is no existing structure to document. But if your project involves an existing home or commercial building, whether it is a kitchen remodel, an ADU conversion, or a tenant improvement, LADBS will typically want an accurate as-built set before reviewing any proposed changes.
Many Los Angeles homeowners are surprised to learn that even a straightforward addition can require a full as-built survey if the property’s original plans are missing or no longer match what was actually built. Older homes in neighborhoods like Silver Lake, Hollywood, and Culver City are especially prone to this, since decades of informal alterations often go unrecorded. Our 3D laser scanning service captures these conditions quickly and accurately, and our ADU permit drawings team handles both the as-built survey and the proposed design set LADBS requires for a complete submittal.
Frequently Asked Questions
Not exactly. Every as-built drawing is created in CAD format, but not every CAD drawing is an as-built. CAD simply refers to the software and file type, while “as-built” refers to what the drawing represents: a field-verified record of existing conditions.
Not always, but it is common, particularly when the property’s original permitted plans are missing, outdated, or do not match current conditions. LADBS reviewers routinely request an as-built set to confirm the true starting point before approving proposed work.
Only if those drawings still match the building exactly. Most properties have seen at least some unpermitted changes over the years, which means original design drawings often no longer reflect reality and will not satisfy LADBS.
