ADU Permits & Bylaw Guide - St. Catharines

Housing and Building Standards Ontario 3 Minutes Read · published May 26, 2026 Flag of Ontario · By Daniel Roy

St. Catharines, Ontario homeowners who want to add an accessory dwelling unit (ADU) must meet municipal zoning and Ontario building rules before renting or occupying the unit. This guide explains the local permitting path: planning/zoning checks, building permits, inspections, and common compliance issues specific to the City of St. Catharines. It focuses on practical action steps you can take today, the municipal offices that enforce rules, and what to prepare for an application. If your property is in a conservation or heritage area, or part of a multi-unit property, additional approvals may be required.

Overview

An ADU is an additional self-contained residential unit on the same lot as a primary dwelling, often called a secondary suite, basement apartment or granny suite. In St. Catharines, ADUs must comply with the Citys zoning by-law and the Ontario Building Code. Typical municipal checks include maximum unit size, parking requirements, entrances, and fire egress. Before construction or rental, confirm that your lot and dwelling type are eligible under the Citys zoning rules and obtain any required permits.

Check zoning before design work to avoid costly rework.

Penalties & Enforcement

Enforcement for unauthorized ADUs is handled by City departments under the Zoning By-law and Building By-law. Specific monetary fines and penalties for non-compliant accessory units are not specified on the City pages listed in Help and Support / Resources below; please consult those official pages for the most current enforcement detail.

  • Monetary fines: not specified on the cited municipal pages; amounts vary by offence and by-law.
  • Escalation: municipalities typically issue orders, tickets, then proceed to court for ongoing breaches; specific escalation steps not specified on the cited municipal pages.
  • Non-monetary sanctions: municipal orders to cease occupancy, orders to remove or alter structures, stop-work orders and court enforcement actions.
  • Enforcer and inspections: Building Division inspects for code compliance and By-law/Planning staff enforce zoning; use official city reporting/contact channels in the Help and Support / Resources section.
  • Appeals and review: appeal routes vary by instrument (e.g., Committee of Adjustment for minor variances); time limits for appeals are prescribed by the specific by-law or provincial statute and are not specified on the cited municipal pages.
If you occupy an ADU without approval you may be ordered to vacate or remove the unit.

Applications & Forms

Typical applications and permits you will encounter:

  • Building permit application: required for structural, plumbing, electrical and major renovations—see City Building Division for forms and submission process; specific fee schedules are not specified on the cited municipal pages.
  • Zoning compliance or zoning confirmation: demonstrate the ADU meets lot coverage, setbacks, parking and use rules; if a variance is needed, apply to the Committee of Adjustment.
  • Fees: permit and review fees apply; fee amounts and payment methods should be confirmed on official City pages in the Help and Support / Resources section.
Collect property documents and a basic floor plan before applying to speed review.

FAQ

Do I need a building permit to create an ADU?
Yes. Structural, plumbing, electrical or major changes to create a self-contained unit generally require a building permit and compliance with the Ontario Building Code.
Can I rent my accessory unit?
Renting is possible if the unit meets zoning and building requirements and any licensing obligations; confirm with City Planning and the Building Division before listing.
How long does permitting take?
Review times vary by application complexity and completeness; check the Citys Building Division and Planning pages for current processing timelines.

How-To

  1. Confirm zoning: review your propertys zoning designation and permitted uses to ensure an ADU is allowed.
  2. Prepare plans: create a floor plan, site plan and list of proposed changes showing exits, smoke alarms, and parking.
  3. Apply for permits: submit building permit applications and any required planning or variance applications to the City.
  4. Undergo inspections: schedule and pass required inspections (framing, electrical, plumbing, final) before occupancy.
  5. Pay fees and comply with orders: pay permit fees and address any compliance orders issued during review or inspection.

Key Takeaways

  • Start with zoning confirmation to avoid later refusals.
  • Building permits and inspections are usually required; plan for timelines and fees.
  • Unauthorized ADUs risk orders to vacate, fines or court action.

Help and Support / Resources

Categories

General Governance and Administration Public Safety Public Health and Welfare Land Use and Zoning Housing and Building Standards Transportation Environmental Protection Parks and Public Spaces Business and Consumer Protection Taxation and Finance Labor and Employment Education Civil Rights and Equity Elections and Campaign Finance Events and Special Uses Signs and Advertising Utilities and Infrastructure Technology and Data
Daniel Roy

Daniel Roy

Municipal Bylaw Analyst

Daniel analyses municipal bylaws across Canadian provinces and territories. He checks every guide against official municipal and provincial sources.