A Chicago two flat deconversion turns a two-unit building back into a single-family home. The work itself is familiar: remove a kitchen, open a stairway, reconnect two floors. The paperwork is where owners get caught. The plans must show the building as it exists today and as it will exist when you finish, and they have to be good enough for the City to review. This article covers what those plans should show and who should prepare them. It does not cover zoning or occupancy rules, because we have no verified source for them. Check those with the Department of Buildings and the zoning office before you buy materials.
What is a two-flat deconversion?
A two-flat is the Chicago building type with one apartment on each floor, usually over a basement. Many were built that way and have stayed that way for a century. A deconversion removes the second kitchen, the second set of entries or utilities, and whatever separates the units, so the whole building works as one home.
Owners do this for different reasons. A family buys a two-flat and wants the upstairs and downstairs as one house. A landlord stops renting the second unit. A buyer wants the street presence of a two-flat with the layout of a single-family. Whatever the reason, the City sees the same thing: a change to the building's layout and use, with real work behind it.
Do you need an architect for a deconversion?
Possibly, and the answer depends on the work, not the label. The City says that for most Express-eligible repair work, no architect or engineer documents are needed. It also says any plan-based permit requires plans prepared by an Illinois-licensed architect or engineer, and for most projects that means an architect or a structural engineer.
A deconversion often lands on the plan-based side, because the work tends to include things the City does not treat as simple repair:
- Removing or relocating walls, including walls between the units.
- Opening a floor to connect two levels with a new stair.
- Changing structure to carry loads that the old layout handled differently.
- Reworking egress, meaning the required ways out of the building.
- Moving or removing plumbing, gas and electrical for the second unit.
The City's list of work that skips a permit is narrow. Repairs qualify only if they avoid cutting away part of an exterior wall, interior wall or partition, subfloor or roof, cutting a structural beam or support, changing required egress, or touching mechanical, electrical, plumbing or fuel gas systems. A deconversion touches nearly every item on that list.
We do not claim to know exactly which permit route your building lands on. That depends on your scope, so confirm it with the Department of Buildings. Our article on when Chicago requires an architect or engineer lays out the triggers the City publishes.
What should the drawings show?
We found no verified City checklist for what a deconversion drawing set must contain. So here is what any competent set should cover, in terms a plan reviewer and a contractor both need. Treat it as the planning list to bring to your design professional, not as a City requirement.
- Existing floor plans. Every level, with the real walls, doors, stairs, kitchens and bathrooms. If no drawings exist, this starts with measuring the building. See as-built drawings in Chicago.
- Proposed floor plans. The same levels after the work, with what is removed, what is new, and what stays.
- Structure. Which walls bear load, what holds up what, and how any removed wall or opened floor is supported. This is the part an architect or structural engineer must stand behind.
- Stairs and egress. How people get in, out and between floors after the change.
- Plumbing, gas and electrical changes. What is capped, removed or rerouted, shown clearly enough for the licensed trades to price and permit their share.
- Demolition notes. What comes out, so the contractor and the reviewer read the same drawing.
A deconversion also changes how many kitchens and dwelling units the building has. We have no verified source on how Chicago zoning or the building code treats that change, so ask the Department of Buildings and the zoning office what applies to your address before you commit to a design.
Which permit program will the plans go through?
The City runs several programs: Express, Standard Plan Review, Self-Cert and Developer Services for moderate to complex projects (City of Chicago). Plans for a deconversion typically go to one of the two plan-based routes.
Standard Plan Review is the City's main process when architectural plans are required. It requires an architect to prepare the drawings, submissions go through the E-Plan system, and every project needs zoning approval. The criteria include residential projects with fewer than 50 dwelling units and the removal of non-load-bearing interior partitions (City of Chicago).
Self-Cert lets an Illinois-licensed architect or structural engineer who completed the City's training seal the drawings and take full responsibility for code compliance (City of Chicago). That puts the legal weight on the professional's seal, which is why Self-Cert is a design decision, not a shortcut for the owner.
Which program fits is something the design professional and the Department of Buildings decide with you. Do not let anyone promise you a permit date.
Who prepares the plans, and where does Akats fit?
Only an Illinois-licensed architect or structural engineer can prepare plans for a plan-based permit. To start such an application, you need to be one of those professionals or a City-licensed expediter (City of Chicago). A contractor, handyman or friend with software cannot stand in.
Akats is a general contractor. We coordinate drawings with licensed design professionals, build what the drawings call for, and handle the permit side. That order helps. When the contractor reads the drawings before they are final, problems surface on paper instead of behind a wall. If you are weighing that setup, see design-build or design-bid-build, and the design-build guide for how the pieces fit.
On older two-flats we often find that the walls between the units are not where an owner expects, that a "temporary" second kitchen was added long after the building was built, and that the plumbing for the upstairs unit runs through the downstairs ceiling. None of this is unusual. All of it is why the existing-conditions drawing comes before the proposed one.
What to ask before you hire anyone
- Who will prepare and seal the drawings, and are they Illinois-licensed?
- Which permit program do you expect this to go through, and why?
- Who documents the existing building if no drawings exist?
- Who coordinates the electrical, plumbing and gas trades on the drawings?
- Who talks to the Department of Buildings if the reviewer has comments?
Planning a deconversion and not sure what the drawings need? Our architectural services team can talk through your building with you. For the wider planning picture on a two-flat, see Chicago two-flat renovation: who does what, from plans to permit.
Common questions
Almost certainly, because the work usually involves removing walls, changing stairs or moving plumbing, gas and electrical, and the City's no-permit list excludes those. Which permit program applies depends on your scope. Confirm with the Department of Buildings before work starts.
If the work goes through a plan-based permit, yes: the City requires plans prepared by an Illinois-licensed architect or engineer, and for most projects an architect or structural engineer. Express repair work usually needs none. Check your scope with the Department of Buildings.
Sometimes the work is mostly cosmetic and layout, but removing a wall or opening a floor can affect load paths, and that is structural. Have a licensed architect or structural engineer look at it. For zoning and unit-count rules, ask the Department of Buildings and the zoning office.
Someone has to document the building as it stands before the new plans can be drawn. That is called an as-built or existing-conditions drawing. Our article on as-built drawings in Chicago explains when you need one.
Sources
- City of Chicago, Department of Buildings: Standard Plan Review Permit Program
- City of Chicago, Department of Buildings: Self-Certified Permit Application Program
- City of Chicago: Guide to Building Permits: What Types of Work Do Not Require a Building Permit?
- City of Chicago: Guide to Building Permits: When Is a Licensed Architect or Engineer Required?
- City of Chicago, Department of Buildings: Permits
- City of Chicago, Department of Buildings: Permit Professional Lookup: Help
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.