Common-interest ownership glossary
A condominium owner holds a unit interest plus an inseparable share of common elements
Condominium describes a legal ownership form, not a building shape. A detached home, townhouse, or apartment-style unit can be organized as a condominium.
Last updated: August 1, 2026
Condominium: definition first
Direct answer: A condominium is a form of common-interest ownership in which a unit is separately owned and carries an undivided percentage interest in the common elements. Under the Illinois Condominium Property Act, the declaration legally describes each unit, allocates its common-element percentage, and identifies common and limited common elements. Unit ownership and the corresponding common-element share ordinarily cannot be separated.
Why it is on the exam: PSI includes condominiums and cooperatives among common-interest ownership forms in Property Ownership and places association regulations in Land Use Controls. Illinois candidates should connect the national distinction to the current Condominium Property Act rather than treat every multifamily building as a condominium.
Private interest
Separately owned unit
Shared interest
Undivided common-element percentage
Governing instrument
Recorded declaration and bylaws
Administration
Unit owners' association and board
Separate deeded unit ownership from cooperative ownership
| Decision point | Condominium | Cooperative |
|---|---|---|
| Resident owns | Unit estate plus inseparable common-element interest | Shares or membership in the entity that owns the property |
| Occupancy right | Flows from unit ownership and condominium instruments | Usually proprietary lease or occupancy agreement |
| Financing focus | Mortgage or lien on the unit interest, subject to project requirements | Loan commonly secured by shares and leasehold interest, with entity-level obligations also relevant |
| Property title | Unit owner holds the described unit interest | Cooperative entity holds title to the building or property |
Read the declaration to find the legal boundary and percentage
Illinois defines a unit as a part of the property designed and intended for independent use. The declaration supplies the unit's legal description, which can use the identifying number shown on the plat. It also allocates a percentage of common-element ownership to each unit.
The percentage is more than a casual estimate of floor area. Under the Act, it is set through the declaration's statutory framework and can affect voting and common expenses. A buyer should use the recorded condominium instruments rather than infer the percentage from unit size alone.
- Locate the unit boundary in the declaration and plat.
- Confirm the allocated common-element percentage.
- Identify limited common elements assigned to the unit.
- Review amendments, bylaws, rules, budgets, reserves, insurance, and assessments.
Limited common does not mean privately deeded space
Common elements are the portions of condominium property outside the units, including limited common elements unless otherwise specified. A limited common element is reserved for the use of one unit or fewer than all units under the declaration, such as a balcony, patio, parking space, or storage area in some projects.
Exclusive use does not automatically convert the limited common element into part of the unit. Maintenance, repair, cost, transfer of use, and alteration depend on the Act and condominium instruments. Illinois section 26 imposes a recorded-amendment process for transfers of limited-common-element use.
Association governance travels with unit ownership
The Illinois unit owners' association administers the property through its elected board of managers, and each unit owner is a member. The declaration, bylaws, rules, budgets, reserves, and board authority shape shared maintenance, insurance, use restrictions, and decision procedures within statutory limits.
Owners must pay their proportionate common expenses as provided by the governing framework, and Illinois law provides an association lien for nonpayment. A unit can be separately conveyed, but it is not separated from the project's financial condition, recorded restrictions, or its common-element obligations.
The balcony marked limited common element
Question: An Illinois declaration assigns a balcony to Unit 5 as a limited common element. The owner argues that exclusive use makes the balcony part of the deeded unit and outside all association authority. Is that correct?
Best answer: No. Exclusive use can be assigned while the balcony remains a limited common element governed by the Act and condominium instruments.
Why: The unit boundary and common-element classification come from the declaration, plat, and statute. Use assignment, maintenance responsibility, alteration rights, and costs must be read separately rather than inferred from exclusivity.
Lock in the distinction
Exam trap
Do not call every apartment-style residence a condominium. The legal documents and ownership structure decide. A rental building and a cooperative can look identical from the sidewalk.
Memory cue
Condo equals unit title plus an inseparable common share. Then open the declaration for boundaries, percentage, and limited elements.
Quick questions
What does a condominium owner own?
The owner holds the unit estate described by the condominium instruments together with its inseparable percentage interest in the common elements.
What is a limited common element?
It is a common element assigned for use by one unit or fewer than all units, subject to the declaration, Act, and other condominium instruments.
Is condominium a building style?
No. It is a legal ownership form. Different physical building types can be submitted to condominium ownership.
Who administers an Illinois condominium?
The unit owners' association is responsible for overall administration through its elected board of managers, within the Act and condominium instruments.
Primary sources and review status
- PSI Illinois Real Estate Candidate Information Bulletin, June 24, 2026
- 765 ILCS 605/2, Illinois Condominium Property Act definitions
- 765 ILCS 605/4, condominium declaration contents
- 765 ILCS 605/18.3, unit owners' association
Checked through August 1, 2026. This definition is an exam-prep explanation, not a substitute for current law or advice about a live dispute. The current official source controls if the outline or Illinois rule changes.