Additional Dwelling Units

In 2023, Council passed a by-law to allow additional dwelling units in South Frontenac to create more housing options. The by-law took effect on January 23, 2024.

An additional dwelling unit (ADU) is a self-contained residential unit with its own kitchen, bathroom facilities and sleeping area on a property that already has a house on it. It can be a space within a principal dwelling like a basement apartment or in-law suite, or a separate building on the same lot close to the principal dwelling.

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Submit a Planning Intake Form  Pay Online   
(submit this form to request a meeting with our planning team to discuss your project or if you are looking for specific information. You will need to submit a sketch with the form.)

General Guidelines

In South Frontenac, you can build up to two additional dwelling units on one property, one or two in the primary dwelling and one in an accessory building for a total of three residential units on one lot. The proposal must meet zoning and building code requirements.

The following general rules apply. See our Zoning By-law for full details.

  • The maximum gross floor area of the unit must be smaller or equal to the floor area of the principal dwelling.
  • In the case where the unit is a separate structure, it must be within 40 metres of the main house.
  • Additional dwelling units must share the same driveway entrance with the principal dwelling
  • Additional dwelling units are prohibited on lands located in a floodplain, within 90 metres of a lake or river, or within 300 metres of highly sensitive (at-capacity) lake trout lakes


This table outlines some of the fees you can expect when building an Additional Dwelling Unit. Fees from third party professionals like designers and water professionals will vary.

Planning Intake meeting $150
Zoning Application (to remove holding overlay for water and to issue Zoning Compliance Certificate $370/$260 if on municipal water
Sewage System Performance Level Review (if needed) $515
Letter of Opinion on water or Hydrogeological Assessment Will vary based on provider
Designer/Draftsperson Will vary based on provider
Building Permit Fee See building permit fees


Grant Programs

Your project may be eligible for a government grant.

Government of Canada Multigenerational home renovation tax credit (MHRTC)

  • The Multigenerational home renovation tax credit (MHRTC) is a new refundable tax credit that can be claimed on your income tax and benefit return starting in tax year 2023.
  • If you are eligible, you can claim this credit for certain renovation expenses to create a self-contained secondary unit. The secondary unit must allow a senior or an adult who is eligible for the disability tax credit to live with a qualifying relative.
  • You can claim up to $50,000 in qualifying expenditures for each qualifying renovation that is completed. The tax credit is 15% of your costs, up to a maximum of $7,500, for each claim you are eligible to make.

Canada Greener Homes Initiative

This program helps homeowners save money and fight climate change by providing grants for energy retrofits.

What is the process to build an ADU?

The process to build an additional dwelling unit is similar to any other zoning or building permit application. It starts with a zoning review, to ensure the project meets the current zoning requirements.

One step unique to ADUs is the requirement of the property owner to demonstrate there is an adequate supply of potable water to support the additional units. This step is not required if the lot is connected to the Sydenham municipal water system.

Once all the zoning requirements are satisfied, we’ll issue a Zoning Compliance Certificate and the property owner can apply for a building permit. The Ontario Building Code lists very specific requirements for ADUs including minimum room sizes, ceiling heights, and specific requirements for exits, windows, plumbing, heating and electrical. We strongly recommend you hire a professional designer who is familiar with the Code to ensure your project meets all the requirements.

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Seven steps to building an ADU graphic

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