What's Actually Happening in DUPage and Lake Counties in 2026
The office-to-residential conversion story in Chicago has been told mostly through the LaSalle Street lens. Downtown Class B office buildings getting reworked into residential. The big city projects with the marketing budgets and the media coverage.
The story most reporters are missing is what is happening in the Chicago suburbs. Oak Brook, Schaumburg, Deerfield, Northbrook, Lisle, Naperville, and a handful of other suburban office corridors are quietly turning into a real conversion pipeline. The math is different. The construction is different. The residents will be different. And the total unit count coming online through this suburban wave will meaningfully exceed what the downtown conversion pipeline delivers.
For developers, investors, and property managers who care about where suburban Chicago multifamily supply is actually coming from over the next three years, this is the story.
Why the Suburban Office Conversion Math is Different
Downtown Chicago office conversion works because the downtown residential rent premium can support the high per-square-foot cost of converting a Class B office building. It only works barely. Most downtown conversion projects need incentive support to close the gap between conversion cost and achievable rent.
Suburban office conversion works for different reasons. The buildings are cheaper to acquire because the suburban office market has been hit harder than downtown. Land value in most suburban office corridors is closer to zero than in the Loop, because there is no alternative use that produces rent. The floor plates are often shallower and easier to convert than downtown towers. Structured parking already exists. And the residential rents in some suburban markets have grown enough that the math starts to work without the same level of incentive support.
The result is a suburban conversion pipeline that is quietly building momentum without the marketing spotlight the downtown projects get.
Where the Activity is Concentrated
Oak Brook is the most visible suburban conversion market. The Hines project on the former McDonald's headquarters campus is the headliner, with residential included as part of a much larger mixed-use redevelopment. But there are smaller Oak Brook office conversion conversations happening as well, tied to the broader corridor repositioning.
Schaumburg has multiple office parks with owners studying conversion. The corridor has seen aggressive office vacancy for years and land values that reflect the reality that office is not coming back at the scale it was. Conversion is one of the few paths that produces value from those buildings.
Deerfield, Northbrook, and Bannockburn along the Lake County corporate corridor have similar conversations. Some buildings are candidates. Others are not. Floor plate, structural system, mechanical infrastructure, and site all determine whether a specific building can convert affordably.
Lisle and parts of Naperville along the I-88 corridor round out the list. Not every Class B office building will convert, but the pipeline of candidates is real.
What Makes a Suburban Office Building a Good Conversion Candidate
The buildings that convert well share several traits. Floor plates in the 60 to 80 foot depth range from window to core work best. Deeper floor plates create too much interior space that cannot get natural light. Column grids that allow for reasonable unit layouts matter. Structural systems that can accept plumbing and mechanical modifications matter. Existing parking capacity that meets residential requirements matters. And a site that supports outdoor amenity space and pedestrian access matters.
The buildings that do not convert well share their own traits. Very deep floor plates. Structural systems that resist modification. Sites that are landlocked between highways or industrial uses. Buildings on speculative land value that will not accept the conversion cost basis. Owners who are unwilling to face the honest math.
The suburban Chicago office corridors have a mix of both. Developers evaluating conversion candidates need a construction team that can walk the building and produce an honest assessment before the acquisition math gets locked in.
The Construction Reality Is Closer to New Build Than Renovation
Office-to-residential conversion is not a renovation project. It is closer to a new build with the structure preserved. That framing matters for how developers, investors, and lenders think about the project.
The plumbing runs are entirely new. Kitchens and bathrooms in every unit means dozens of new supply and waste risers where the original building had a handful. Mechanical systems are usually completely reworked, because office HVAC is not what residential needs. Electrical loads and distribution get redesigned. Window openings sometimes need modification. Envelope work is common. Interior demolition can be extensive.
The trades involved and the sequencing look more like ground-up multifamily than typical office renovation. Contractors who have not done conversion work often underestimate the plumbing and mechanical scope, and the surprises show up in the field during construction. Contractors who have done conversion work know how to walk the building, price the scope honestly, and sequence the work to hit the schedule.
The Resident Profile Suburban Conversion Serves
Suburban office conversion residents look different from downtown conversion residents. Most of them are choosing the suburban location for a reason. Job proximity. School district. Family stage. Cost. They are not downtown renters accepting a suburban compromise. They are suburban renters who now have a housing option they did not have before.
That resident profile drives the amenity, unit mix, and finish decisions on suburban conversion projects. Larger unit sizes than downtown. More family-friendly units. Parking that respects the reality that suburban residents drive. Amenities weighted toward family and fitness rather than urban work-from-home programming. Building design and finish choices that suit the local market rather than the downtown aesthetic.
What Property Managers Should Understand
Suburban office conversion projects come with operational considerations that differ from ground-up suburban multifamily. Building systems may include legacy office elements that were kept for cost reasons. Some suburban conversions include ground floor amenity or commercial space that requires different management than a standard multifamily. HVAC and mechanical systems may have quirks that residents notice.
PMs taking over a suburban conversion asset benefit from understanding the construction history of the building. The best operators walk the buildings during construction, meet the trade partners, and understand what got kept versus what got replaced. That knowledge pays back through the operating years.
The Total Pipeline Is Bigger Than the Coverage Suggests
Nobody has written the definitive suburban Chicago office conversion story yet. The projects are more distributed geographically than the downtown pipeline. Each individual project is smaller than a downtown tower conversion. The developers doing the work are not the same firms that get the downtown press coverage. And the projects are quietly delivering without ribbon-cutting events.
But the cumulative unit count coming through suburban conversion over the next three years will meaningfully outstrip what downtown Chicago produces. Investors and PMs paying attention now will see the pattern before the trade press catches up.
Final Thought
The Chicago suburban office-to-residential conversion wave is real, distributed, and quietly reshaping supply in DuPage and Lake counties. The developers, investors, and PMs who understand the specific building traits that make suburban conversion work are the ones capturing the opportunity.
The construction on these projects is closer to new build than renovation. Getting the right contractor into the conversation early is the difference between a project that pencils and a project that surprises everyone in the field.
Studying a Suburban Office Building for Conversion?
ETI Construction works with developers, investors, and asset managers evaluating Chicago suburban office buildings for residential conversion. Our team walks buildings, produces honest construction assessments, and helps developers understand what a specific candidate will actually cost to convert.
If you are looking at a suburban office building and thinking through the conversion math, we can help you walk it before you commit.
If you are working on a suburban Chicago multifamily project, walk it with us. Request a walk