What an as-built drawing is, and why your project starts with one
An as-built drawing is a measured, current record of what your house actually is — every wall, opening, ceiling height and exterior dimension as they exist today. It is not the plan your house was built from. Those two documents disagree more often than homeowners expect, and every design decision you make downstream is only as good as the dimensions underneath it.
Original plans are not as-builts
A set of original construction drawings tells you what someone intended to build in the year it was drawn. It does not account for the field changes made during construction, the previous owner's addition, the wall someone moved, or the patio that got enclosed. On a house of any age, some of those changes were permitted and some were not, and the paper record rarely reflects all of them.
There is also a simpler problem: for a lot of Phoenix homes, the original plans no longer exist in any form the owner can get their hands on. An as-built is how you get a reliable drawing of your own house regardless.
What guessing actually costs, by project type
Skipping an accurate as-built does not make the real dimensions go away. It moves the moment you find them to a more expensive point in the project.
ADU. A size cap or setback calculated against an assumed lot size, found wrong only after the design is drawn and submitted.
Pool. An equipment pad or barrier layout that does not fit once the yard's real dimensions and existing structures are measured.
Addition. Tie-in points and roof lines designed against exterior walls nobody measured, discovered when construction starts.
Garage conversion. Fire-separation, egress and ceiling-height requirements evaluated against the wrong existing dimensions.
Patio or ramada. A setback that looked fine on paper and violates the real property line once it is field-verified.
Remodel. An interior layout built on guessed room dimensions, requiring a redraw when real measurements arrive.
Every one of those is a redraw, a resubmittal, or a change order. All of them are cheaper than the alternative, which is finding out during construction.
What a complete as-built package contains
A usable package is more than a floor plan. It includes measured floor plans with room dimensions and ceiling heights, exterior elevations, a site plan locating the house and every accessory structure against the property lines, and notes on what was observed about existing construction. It becomes the base drawing every future project on the house is built from — once, properly, instead of re-measured badly each time.
What the measuring actually involves
Documenting a typical Phoenix house is a site visit, not a survey crew. Room by room, exterior wall by exterior wall, with ceiling heights, window and door openings, and the location of structures relative to property lines recorded as they are — including the things that do not match the paperwork. The field measurements then get drawn up into a clean set you can hand to anyone.
Worth being precise about one boundary: an as-built documents the building. It is not a licensed land survey, and it does not replace one where a lender, the City or a boundary dispute requires a surveyor's seal. For most residential design work it is exactly what is needed; where a survey is genuinely required, you will be told so rather than sold around it.
It is also part of your permit record
Where a project touches existing construction, a plan reviewer needs to see the existing condition, not just the proposed one. An accurate as-built is what lets a set show both. If your house has work in it that was never permitted, an as-built is also the first honest step toward resolving that — you cannot legalize what nobody has documented.
Get the free guide (PDF)
The full 18-page Phoenix As-Built Documentation Guide walks through the measuring process, what a complete package includes, what accurate documentation costs, and a readiness checklist for your own home. It is free — enter your email and it comes straight to you.
See also: ADU requirements · Home addition permits · Garage conversion permits · Services