As-built drawings (also called existing-conditions drawings) record a building the way it actually stands, not the way an old plan says. We found no verified City rule that requires them as such. You need them in practice when you plan work that needs plans, such as moving walls, opening floors, adding a dormer or converting a two-flat, and the building has no reliable drawings. Check with the Department of Buildings what your permit asks for.
As-built drawings in Chicago are measured drawings of the building as it exists today. An architect or structural engineer needs them whenever new plans must be drawn over an old building, because the old plans, if any, are often wrong. This page covers when you need them, who makes them, and what to do if you bought a building with nothing on paper.
What are as-built drawings, and does the City require them?
As-built drawings show the real floor plans, wall locations, stairs, openings and structure of a building, based on measuring it. They are also called existing-conditions drawings or measured drawings. They are different from the proposed plans that show what you want to build.
We have no verified City rule that says "an as-built set is required" as a standalone item. What we do have is the City's rule for new work: any plan-based permit requires plans prepared by an Illinois-licensed architect or engineer. Those plans draw the new work on top of the existing building. If the existing building is not documented correctly, the new plans are built on guesses. The City's Standard Plan Review is the route when architectural plans are required. Which documents your specific permit wants is a question for the Department of Buildings.
When do you actually need them?
In practice, as-builts are the first step when all of these are true: the work needs plans, and the building has no reliable drawings. Common cases:
- Opening or moving walls and floors. The City's no-permit list excludes work that cuts into interior walls, partitions or subfloors, or removes a structural support. The plans for that need to know what is there.
- Converting a building. A two-flat deconversion starts with what exists on each floor.
- Adding to a building. A dormer, rear addition or attic room needs the roof and walls documented.
- Buying an older building. You are paying for a structure whose layout and alterations nobody can confirm.
- Fixing a violation that needs drawings. If the repair is structural, an architect or engineer must draw it.
If you only need a routine repair that goes through the Express program, you usually do not need as-builts at all. See do you need an architect for a building permit for the line between the two.
Who makes them, and what if the plans are missing?
Someone has to go measure the building. That can be the architect, the structural engineer, or a drafter working under them. The result is a set of existing floor plans, and, depending on the job, sections, elevations and structural notes. Measuring is not the same as stamping: the licensed architect or structural engineer who prepares the permit plans takes responsibility for them.
Old Chicago buildings are full of changes that never made it onto paper: walls moved, a second kitchen added, a porch rebuilt, plaster hiding what holds the floor up. Owners who buy a building with no plans often learn this only when a wall is opened. Documenting it first costs time up front and saves surprises later.
Akats coordinates drawings with licensed design professionals and builds from them. If you have a building with no plans and a project in mind, our architectural services team can start the process, and the design-build guide explains how one team carries it from measurements to a finished job. For a bigger renovation, Chicago two-flat renovation planning shows who does what.
Common questions
We found no verified City rule requiring an as-built set by that name. Plan-based permits need plans prepared by an Illinois-licensed architect or engineer, and those plans need accurate existing conditions. Ask the Department of Buildings what your permit application requires.
Have the building measured. An architect, structural engineer or a drafter working under them records the existing floor plans and structure. That becomes the base for any new design, so the work is drawn from what is really there.
Sources
- City of Chicago: Guide to Building Permits: When Is a Licensed Architect or Engineer Required?
- City of Chicago, Department of Buildings: Standard Plan Review Permit Program
- City of Chicago: Guide to Building Permits: What Types of Work Do Not Require a Building Permit?
Facts last checked: October 7, 2026.
This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.