How Highland Park Handles Accessory Structures: A Practical Guide

Highland Park maintains 38 local ordinances across all categories, and 4 of those deal specifically with accessory structures. Here is a breakdown of what the city actually requires, what is prohibited, and where Highland Park falls on the strict-to-permissive spectrum compared to other cities.

Carport Rules

Highland Park regulates carports as accessory structures under Title XV, Chapter 150 of the Zoning Code (Article II Definitions and Article VII Area, Bulk and Density). Permitted accessory uses are governed by Article IV (Section 150.401 et seq.) and dimensional limits including residential lot development requirements appear in Section 150.703. A separate building permit is required from the Building Division under Chapter 170 (Building Code), which adopts the 2018 International Residential Code as locally amended.

Key details: Zoning Chapter: Title XV Ch. 150. Dimensional Section: Sec. 150.703. Definitions: Sec. 150.202. Building Code: Title XVII Ch. 170 / 2018 IRC. Planning Contact: 847-432-0867.

Building a carport without zoning clearance from the Planning Division or a Title XVII Chapter 170 building permit, or in violation of the Article VII setback, height, or yard-coverage standards, is a Zoning Code violation. The Community Development Department may issue stop-work orders, require removal or after-the-fact permitting, and assess fines under Chapter 150 and the Chapter 10 General Penalty (each day a separate offense). Lots in a historic district that proceed without Historic Preservation Commission review face additional enforcement under Chapter 28.

ADU Rules

Highland Park does not appear to have a specific ADU ordinance. Accessory dwelling units may require zoning approval under Chapter 150. Illinois has no statewide ADU mandate, so the city's own zoning controls.

Key details: ADU Ordinance: No specific ADU ordinance identified. State Law: No statewide ADU mandate. Approval: Zoning approval or variance may be needed. Home Rule: Highland Park has home rule authority. Contact: Community Development: 847-432-0808.

Unpermitted ADUs face stop-work orders and removal or legalization requirements. Fines of $500–$2,000 apply for unpermitted construction. Properties with illegal ADUs may face title issues at sale.

Shed Rules

Building permits required for sheds in Highland Park. The city publishes Shed Permit Requirements (v2.1). Applications must include property owner authorization and be submitted through the Civic Access Portal.

Key details: Permit: Required for all sheds. Guide: Shed Permit Requirements v2.1. Submittal: Via Civic Access Portal. Zoning: Article VII — setbacks and lot coverage. Contact: Building Division: 847-432-0808.

Unpermitted structures receive a notice to either obtain a retroactive permit (with double fees) or remove the structure within 60 days. Fines of $100–$500 apply for non-compliance.

Garage Conversions

Highland Park Code of Ordinances Chapter 150 (Zoning) limits detached garages in residential districts by lot coverage and accessory-structure square footage, with maximum size tied to a percentage of the rear yard or an absolute cap (typically around 1,000 sq ft, whichever is less). All work requires a building permit under Chapter 170 (Building Code), which adopts the 2018 International Building/Residential Codes.

Key details: Zoning Code: Highland Park Code Ch. 150, Art. VII. Building Code: Ch. 170 (2018 IBC/IRC adopted). Max Accessory Area: ~1,000 sq ft or % of rear yard, whichever is less. Required Permit: Yes — Community Development Dept.. Conversion to ADU: Separate change-of-use & ADU approval required.

Constructing or expanding a garage in Highland Park without a permit, or exceeding the rear-yard coverage and accessory floor-area caps in Chapter 150, is a zoning violation. The Community Development Department may issue stop-work orders, require demolition or modification, and impose after-the-fact permit fees. Repeat or unresolved violations can be cited to the City's administrative hearing officer.

The Bottom Line

Highland Park's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Highland Park is broadly strict or permissive.

These rules come from Highland Park's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.