Chicago, Ill., Mun. Code ch. 13-20 § 13-20-510
Definitions (Chicago Building Inspection Code (Chapter 13-20))
Operative Text
For the purposes of this Article, the following additional definitions shall apply: " Alter " or " altered " or " alteration " or " change " means any action pertaining to a sign or sign structure that requires the issuance of a new permit under Section 13-20-550 , including but not limited to, any modification, relocation, re-erection, conversion from on-premise to off-premise (or vice versa), conversion from static image to dynamic image (or vice versa), conversion in dynamic technology, raising or lowering its height, changing its angle, adding extensions, enlarging its dimensions, deviating from approved permit drawings or supporting documents, or changing the address to which the permit applies. " Owner or lessee of the real property " means: (1) the owner of the real property on which any on-premise or off-premise sign is located; or (2) any on-premise tenant of an owner who maintains an on-premise sign on such owner's real property. For purposes of this definition, the term "owner or lessee of the real property" shall not mean the owner or lessee of an off- premise sign asset or account or of an off-premise sign structure asset or account, or the lessee of air space or exterior wall space for an off-premise sign. The definition of "owner or lessee of the real property" added by the amendatory ordinance of 2017, effective January 1, 2018, is intended to clarify, rather than to change, existing law. Signs. Sign(s) mean any name, identification, description, display, illustration, or character which: (1) is affixed to, or represented directly or indirectly upon, a building, structure, or piece of land; and (2) directs attention to an object, product, place, activity, person, institution, organization, or business. For purposes of this definition, the term "sign(s)" shall also include any item defined as a "sign" in Section 17-17-02159 . The language added to this definition by the amendatory ordinance of 2017, effective January 1, 2018, is intended to clarify, rather than to change, existing law. Signs (electrical). Electrical signs are signs that are electrically illuminated. " Dynamic image display sign " means any sign, or portion thereof, with characteristics that appear to have movement or that appear to change, caused by any method other than physically removing and replacing the sign or its components, whether the apparent movement or change is in the display, the sign structure itself, or any other component of the sign. This includes a display that incorporates a technology or method allowing the sign face to change the image without having to physically or mechanically replace the sign face or its components. This also includes any rotating, revolving, moving, blinking, or animated display and any display that incorporates rotating panels, LED lights manipulated through digital input, "digital ink" or any other method or technology that allows the sign face to present a series of images or displays. " Flat signs " means signs which are placed flat against the building or structure from which they are supported and which run parallel thereto. Signs supported from a canopy are deemed to be flat signs when they are single face. " Ground signs " means signs supported by a structure which rests on or in the ground. " Luminance " means the photometric measure of luminous intensity per unit area of light travelling in a given direction. Luminance is measured in candelas per square meters or "nits." " Motion " or " moving " means the depiction of movement or change of position of text, images or graphics. Motion or moving shall include, but not be limited to, visual effects such as dissolving and fading text and images, travelling, running sequential text, graphic bursts, lighting that resembles zooming, twinkling or sparkling, changes in light or color, transitory bursts of light intensity, moving patterns or bands of light, expanding or contracting shapes, and similar actions. " Nits " means a unit of measurement of brightness or luminance. One nit is equivalent to one candela per square meter. " Off-premise sign " has the meaning ascribed to that term in Section 17-17-02108 . " On-premise sign " has the meaning ascribed to that term in Section 17-17-02109 . " Projecting signs " means signs which project obliquely or at right angles from the building or structure from which they are supported. " Roof signs. " Roof signs are signs which are erected on and supported by the roof of a building or structure. " Static sign " means a sign that does not rotate, move, or have any appearance of changing or movement in the sign, sign components or structure. A "static sign" shall not include any sign that has any characteristics of a dynamic image display sign. " Twirl time " means the time it takes for static text, images or graphics on a dynamic image display sign to change to different text, images or graphics. (Added Coun. J. 11-3-99, p. 13842, § 3; Amend Coun. J. 4-24-12, p. 25060, § 3; Amend Coun. J. 4-30-14, p. 80382, § 3; Amend Coun. J. 11-21-17, p. 61755, Art. I, § 6)
Section 13-20-510 of the Chicago Municipal Code establishes the working vocabulary for the sign regulations contained in this Article. It defines key terms such as "alteration," "dynamic image display sign," "static sign," "on-premise sign," "off-premise sign," and related concepts like "luminance," "nits," and "twirl time." These definitions determine how the broader sign rules are interpreted and applied, setting the boundaries for what counts as a sign, what counts as a change requiring a new permit, and who qualifies as an "owner or lessee of the real property" for regulatory purposes. The 2017 amendments clarified—rather than changed—certain definitions effective January 1, 2018.
Plain English — not legal advice.
Property owners and managers operating in Chicago should be familiar with the definitions in § 13-20-510, because these terms govern whether a sign modification triggers the permit requirements found elsewhere in Chapter 13-20. For example, the broad definition of "alter" or "alteration" means that actions such as changing a sign's height, angle, or technology type—including converting a static sign to a dynamic image display sign—generally require a new permit under Section 13-20-550. Operators who maintain on-premise signs on their property are also specifically included in the definition of "owner or lessee of the real property," which affects their regulatory responsibilities under this Article.
General guidance for property managers — not legal advice for your specific situation. Consult an attorney for advice on your case.
Tenants who maintain on-premise signs on a landlord's property should be aware that § 13-20-510 explicitly includes such tenants within the definition of "owner or lessee of the real property," which can carry sign-related obligations under Chicago's sign regulations. If a tenant makes changes to a sign—such as converting it from a static to a dynamic image display, or altering its dimensions—those actions may fall within the Article's definition of "alteration" and could require a new permit. Tenants with questions about how these definitions affect their signage rights or responsibilities may wish to consult the Chicago Department of Housing or a tenant-rights organization familiar with municipal code compliance.
General guidance for tenants — not legal advice for your specific situation. Consult a tenant-rights organization or attorney for advice on your case.
Generated October 14, 2026 — auto-generated, not yet human-reviewed. See /transparency for methodology.
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