The simple answer
An as-built drawing is a measured drawing of what is already built. For residential projects, that usually means documenting the existing floor plan, room layout, walls, doors, windows, and major dimensions so future work can be planned from a reliable base.
When as-built drawings are useful
You are planning a remodel or addition and do not have accurate existing plans.
A contractor, designer, engineer, or city reviewer needs existing-condition drawings before moving forward.
A previous owner changed the home and the current layout does not match old plans or assessor records.
You need to document an existing structure before preparing permit drawings or correction plans.
How the as-built process usually works
The goal is not to overcomplicate the project. The goal is to create a clean record of the existing condition so the next person — homeowner, contractor, designer, engineer, or city reviewer — is not relying on guesses.
Review available records
Old plans, assessor sketches, permit history, photos, and listing information can help identify what may or may not match the current home.
Measure the existing condition
The home or structure is measured so the current layout, rooms, openings, walls, and key dimensions can be drafted accurately.
Create existing-condition drawings
As-built plans typically show the current floor plan and may include exterior dimensions, room labels, openings, notes, and other items needed for the next step.
Use the as-built as a starting point
Once the existing condition is documented, it can support remodel design, permit plans, engineering coordination, or city-requested documentation.
What can as-built drawings be used for?
As-built drawings are not only for large projects. They are useful any time the existing condition matters and the old records are missing, incomplete, outdated, or inaccurate.
- Remodel planning and design layout studies
- Room additions and detached structure tie-ins
- Garage conversions, patio enclosures, and existing work questions
- Permit corrections or city-requested documentation
- Contractor bidding and scope coordination
- Engineering review when existing structure needs to be understood
Are as-builts the same as permit plans?
Not exactly. As-builts show what exists now. Permit plans usually show proposed work and code-related information for city review. On many remodels, the as-built becomes the base drawing used to prepare the proposed permit set.
Why accuracy matters
Bad existing drawings can create bad bids, design conflicts, missed structural questions, and confusing permit comments. A measured starting point helps reduce surprises before the project moves further into design or review.
How this connects to unpermitted work
If a city has flagged an existing addition, garage conversion, patio enclosure, or other work, as-built drawings are often one of the first documents needed to explain what is currently there. From there, the project may require permit drawings, contractor verification, or engineering input depending on the condition.
For more on that situation, see our guide on unpermitted additions in Arizona.
Need existing-condition drawings?
Residential Design provides as-built drawing services for Arizona homeowners, contractors, and property owners who need a clearer starting point before a remodel, addition, or permit-related project.