# Can I add a rental unit to a house in Hamilton or Niagara? > Can you add a rental unit to a house in Hamilton or Niagara? What Ontario law, Hamilton and St. Catharines say, and the permit a renovation needs. - Canonical HTML: https://www.rebornrenos.com/guides/adding-a-rental-unit/ - Section: Home > Guides > Adding a rental unit - Business: Reborn Renos, 4048 Stadelbauer Drive, Beamsville, ON, Canada (serves Beamsville, Lincoln, Grimsby, Stoney Creek, Hamilton, St. Catharines, Thorold, Niagara Falls) - Phone: (905) 920-1418 | Email: michal.gagatrs@gmail.com - Page updated: 2026-11-02 --- Guides Usually yes. Ontario's Planning Act does not let a municipality prohibit up to three units on a parcel of urban residential land: a second or third unit in a detached house, semi-detached house or rowhouse, or one in a building behind it, within the limits the law sets. Hamilton and St. Catharines publish their own rules, and every new unit needs a building permit. Have the city confirm your lot first. ## What does Ontario's Planning Act say about extra units? It limits what a municipality's official plan may do. It says: “No official plan may contain any policy that has the effect of prohibiting the use of,” and then lists the cases, including these two: - “two residential units in a detached house, semi-detached house or rowhouse on a parcel of urban residential land, if all buildings and structures ancillary to the detached house, semi-detached house or rowhouse cumulatively contain no more than one residential unit” - “three residential units in a detached house, semi-detached house or rowhouse on a parcel of urban residential land, if no building or structure ancillary to the detached house, semi-detached house or rowhouse contains any residential units” [(Planning Act, s. 16(3))](https://www.ontario.ca/laws/statute/90p13#BK31) A third case covers one unit in a building behind the house. For zoning by-laws, section 35.1 says: “The authority to pass a by-law under section 34 does not include the authority to pass a by-law that prohibits the use of” the same units. [(Planning Act, s. 35.1(1))](https://www.ontario.ca/laws/statute/90p13#BK58) On parking, no official plan may contain a policy that has the effect of “requiring more than one parking space to be provided and maintained in connection with a residential unit referred to in subsection (3) other than the primary residential unit”. [(Planning Act, s. 16(3.1))](https://www.ontario.ca/laws/statute/90p13#BK31) Whether your lot counts as urban residential land is a question for the city. ## What does the Ontario government tell owners to do? Its guide defines the thing: “A second unit is a self-contained dwelling unit with a private kitchen, bathroom facilities and sleeping areas.” It tells owners to start with the city: “Before deciding to add a second unit, it is important that you first speak with your local municipal planning and building departments.” It warns that “If you cannot comply with your municipality's by-laws, you will not be able to add a second unit.” And on permits: “To add a second unit in your house, you will need a building permit.” [(Government of Ontario, Add a second unit in your house)](https://www.ontario.ca/page/add-second-unit-your-house) Two cautions from the same page. It carries this note: “Some parts of this guide may not accurately reflect recent changes to land use planning rules introduced under the More Homes Built Faster Act, 2022.” So use it for the permit and Building Code steps, and use the Planning Act above for the zoning rights. It also covers fire and electrical work: “When adding a second unit, the Building Code requires a 30-minute fire separation between units, and also between units and common areas.” and “You will need to get a separate electrical permit to do the electrical work in your second unit and the ESA will need to inspect the electrical work in your second unit.” [(Government of Ontario, Add a second unit in your house)](https://www.ontario.ca/page/add-second-unit-your-house) ## What do Hamilton and St. Catharines publish about extra units? **What two Niagara-area cities say about additional dwelling units, read November 1, 2026** | Municipality | What its page says | Link | | --- | --- | --- | | Hamilton, additional dwelling units | “In May 2021, amendments were made to the City's Zoning By-laws to permit Additional Dwelling Units (ADUs) in Hamilton.” And: “We have a dedicated Additional Dwelling Unit Team to review and issue ADU building permits for existing single family dwellings including up to two internal units & one detached unit.” To check a lot: “To determine if a property is eligible for an Additional Dwelling Unit, look up the address using the Interactive Zoning Mapping”. | [City of Hamilton, Additional Dwelling Units (ADU)](https://www.hamilton.ca/build-invest-grow/construction-renovation/residential-building-renovation/additional-dwelling-units) | | Hamilton, building permits | Its list of projects that require a building permit includes “adding additional dwelling units (ADU Internal), including municipal addressing and street naming”. | [City of Hamilton, Building Permit Application Requirements](https://www.hamilton.ca/build-invest-grow/construction-renovation/residential-building-renovation/building-permit) | | St. Catharines, zoning | Its April 8, 2024 zoning amendment includes “Permissions for two additional residential units (accessory dwelling units) with detached, semi-detached, or townhouse dwellings, including size, height, setbacks, and parking.” | [City of St. Catharines, Zoning](https://www.stcatharines.ca/planning-and-development/zoning/) | | St. Catharines, building permit | “Yes, constructing an ADU in St. Catharines requires a building permit to ensure compliance with the Ontario Building Code and the City's Zoning By-law.” | [City of St. Catharines, Pre-Approved Detached ADU Designs](https://www.stcatharines.ca/building-and-renovating/pre-approved-detached-accessory-dwelling-unit-designs/) | If a design does not fit the zoning, Hamilton's page says: “If the proposed ADU design does not conform to the Zoning By-law then an application can be made for a minor variance.” [(City of Hamilton, Additional Dwelling Units)](https://www.hamilton.ca/build-invest-grow/construction-renovation/residential-building-renovation/additional-dwelling-units) We have not quoted Niagara Falls, Thorold, Grimsby or the other Niagara towns here. Ask yours. ## Does a new rental unit need a building permit? Yes. The Building Code Act, 1992 says: “No person shall construct or demolish a building or cause a building to be constructed or demolished unless a permit has been issued therefor by the chief building official.” [(Building Code Act, 1992, s. 8(1))](https://www.ontario.ca/laws/statute/92b23#BK17) The Act defines the word: ““construct” means to do anything in the erection, installation, extension or material alteration or repair of a building”. [(Building Code Act, 1992, s. 1(1))](https://www.ontario.ca/laws/statute/92b23#BK1) The Building Code says who applies: “the owner of the property on which the proposed construction or demolition is to take place” or “the authorized agent of the owner”. [(Building Code, O. Reg. 332/12, Division C, 1.3.1.2)](https://www.ontario.ca/laws/regulation/120332) More on permits for other kinds of work is in [permits for rental renovations](https://www.rebornrenos.com/guides/permits-for-rental-renovations/). ## What does it mean for my job? The owner (or the owner's agent) deals with the zoning check and the permit. Reborn Renos builds the inside. New rental unit development and the creation of additional rental units are larger projects, quoted separately, and a bigger job gets its own written quote with every line priced. The work is full interior construction: framing, separation walls, drywall, paint, floors, kitchen cabinets, doors, trim and millwork. See [adding a rental unit](https://www.rebornrenos.com/properties/rental-units/) and [apartment and commercial renovations](https://www.rebornrenos.com/properties/renovations/). The walls are on [walls, framing and drywall](https://www.rebornrenos.com/homes/walls-and-drywall/). Before you book, ask whoever you hire who applies for the permit and when the inspections happen. If the space has had a leak, see [water damage and mold in rentals](https://www.rebornrenos.com/guides/water-damage-and-mold-in-rentals/). Two more towns in detail: [Niagara Falls](https://www.rebornrenos.com/areas/niagara-falls/) allows three dwelling units on most lots with a parking space for each added unit, and [St. Catharines](https://www.rebornrenos.com/areas/st-catharines/) lists grants for added units. Investors weighing a conversion can start at [work for real estate investors](https://www.rebornrenos.com/properties/investors/). We work in Beamsville, Lincoln, Grimsby, Stoney Creek, Hamilton, St. Catharines, Thorold and Niagara Falls. Call [(905) 920-1418](tel:+19059201418), Monday to Saturday, 7 am to 7 pm, or send the details on the [request page](https://www.rebornrenos.com/request/). This is a plain summary, not legal advice. The linked law is what counts. Published by Reborn Renos, Beamsville. Updated November 2, 2026. Free to share and quote, with a link back to this page. ## Planning a unit? Monday to Saturday, 7 am to 7 pm. Tell us the property and what you want built. [Call (905) 920-1418](tel:+19059201418) --- Reborn Renos. Call (905) 920-1418. Full site: https://www.rebornrenos.com/