ADUSearch is a tool that empowers property owners, industry professionals, policymakers, non-profit housing providers, and researchers to see the potential of detached ADUs in municipalities across Canada. In particular, the tool provides the ability to explore the physical and financial feasibility of building detached ADUs in compliance with local zoning bylaws on both a lot-by-lot basis and at a neighbourhood level.

ADUSearch doesn’t build ADUs–  instead, we enable ADU construction from citizens and industry professionals while encouraging municipal policymakers across Canada to discover the potential of ADU development in their communities.

Having mapped millions of residential lots in Canada, all of which are subject to different zoning bylaws and regulations, total accuracy is not guaranteed. Moreover, since the physical and policy landscapes of municipalities are constantly evolving, it is possible that changes have occurred since a municipality was mapped.

However, we estimate that over 98% of the lots we have mapped are accurate from a zoning and geospatial basis as our team employs a rigorous policy review process and acquires the most current data available whenever possible. We are aware of a few specific issues regarding miscategorization due to data issues but ongoing updates to our tool and the data used will minimize these accuracy issues. As the tool is for information purposes only, we advise contacting your municipality before moving forward with any development plans. 

Additionally, the tool does not map any regulations related to provincial building codes, municipal services (sewer and hydro), nor design specifications that cannot be captured in our GIS model. For example, perhaps a lot shows up as green (categorized as suitable) but has hydro lines in close proximity that would restrict a detached ADU. ADUSearch would not be able to capture those site-specific features that would require a municipality and/or professional to review.

If you think you found a data accuracy error, please let us know by using the contact form on our Contact page.

The categorization is determined through a comprehensive review of a municipality’s bylaws as well as other planning policies. Through this analysis (in many cases reviewed and/or done in partnership with the municipality), a series of standardized gateways based on the requirements of existing bylaws and regulations are created. These gateways determine whether a particular lot meets the bylaw requirements, and the gateways are paired with geospatial data to allow a model to calculate each lot’s estimated buildable area. From there, we test the minimum size of ADU (as specified by the municipal bylaws) to see if it would fit within that area.

This entire process is loosely standardized but is custom built according to the municipal zoning bylaws. In general, the categories are as follows:

Red (not suitable for a detached ADU): Lot does not meet basic zoning and/or building type criteria and is not suitable for building a detached ADU. 

Yellow (not suitable for a detached ADU. May be suitable for internal/attached ADU): Lot meets zoning and building type requirements but may not have enough buildable area, or municipality may restrict detached ADUs in this area and is therefore, only potentially eligible for an internal or attached ADU. As our tool cannot assess the various regulations for internal/attached ADUs, it flags the possibility for users, should their lot not be suitable for a detached ADU.

Light Green (potentially suitable for a detached ADU): Lot meets zoning, building type, and buildable area requirements, but may have additional requirements and/or restrictions (such as permit needed in flood plain areas).Dark Green (suitable for a detached ADU): Lot meets the zoning, building type, and buildable area requirements and is suitable for building a minimum size detached ADU.

In the property and neighbourhood views of the tool, our model applies a standardized detached ADU size for a detached ADU that would meet the basic size requirements of the municipal zoning bylaws. In the absence of a specific minimum size dictated by the municipality, we assume the minimum size requirements of the provincial building codes.

For the Affordability Layers, we created a custom financial model that assumes a 1-storey detached structure on cement slab with 40.0 m2/431 sq ft. area and separate utility connections from the main dwelling. The inside of the ADU is also assumed to have only one bedroom, one bathroom, one laundry, and standard finishes and appliances. Finally, we assume one additional parking space is required for the ADU on the property. 

The “Homeowner Affordability” function (under the “Layers” tab) is designed to inform users whether an average 2-person household in a dissemination area could afford to build a detached ADU based on their likelihood of getting a loan from a financial institution and local construction cost data. 

In order to determine an area’s affordability outcomes, our financial models apply average or median values for several data points including existing home equity, total household income, household debt (which was pulled from provincial and regional reports), interest rates, and down payment amounts. 

These models and the mapped layers are designed to assist municipal officials, policymakers, and researchers to better understand the financial constraints of this type of housing and, in turn, explore how to support property owners in financing ADU construction. At the property owner level, these models provide an “average household” comparison and the actual affordability of an ADU will vary depending on how the individual financial factors outlined above (i.e. actual home equity, household income, household debt, etc.) differ from the calculated average. 

For a more detailed breakdown of the financial model, please refer to our Financial Modelling Report on the Data Exports page.

The “Renter Affordability” function (under the “Layers” tab) is designed to inform users whether a renter can afford to rent an ADU based on (1) a median rental income at a 30% affordability threshold and (2) the assumption that the ADU that is priced only at a cost recovery point (i.e. the property owner only recovering their costs and not making any profit).

As the cost recovery point is likely the price floor for any ADU rental, it can be reasonably assumed that weak renter affordability at the dissemination area level would entail even weaker renter affordability (i.e. high, expensive rental costs) when market rent is being charged. 

It is also important to note that rent costs are also significantly impacted by the actual size, location, and features of an ADU. 

For a more detailed breakdown of the financial model, please refer to our Financial Modelling Report on the Data Exports page.

ADU stands for “Accessory” or “Additional Dwelling Unit.” These secondary living spaces are also known as:

  • Additional Residential Units (ARUs)
  • Accessory dwelling units
  • Basement apartments
  • Carriage houses
  • Coach houses
  • Garage apartments
  • Garden suites
  • Granny flats
  • In-law suites
  • Laneway houses
  • Second units
  • Secondary dwelling units
  • Secondary suites
  • Subsidiary dwelling units

ADUs can be inside the main dwelling (e.g., basement apartment), attached to the main house, or completely detached from the main dwelling. Regardless, all types of ADUs must (1) be on a property with an existing main dwelling and (2) contain their own private kitchen and bathroom facilities.

Our tool focuses on detached ADUs – which are also known as DADUs.

Internal ADUs – A type of ADU wherein the additional unit is located within the main dwelling unit (e.g., in the basement). 

Attached ADUs – A type of ADU that shares at least one common wall with the main dwelling unit. 

Detached ADUs – A type of ADU that is located in a separate structure that is on the same lot and that does not share any common walls with the main dwelling unit. 

ADUs provide numerous benefits in a variety of ways.

ADUs benefit property owners by:

  • Being a flexible housing unit that allows for a variety of uses and occupancy depending on the current needs of the existing owners
  • Providing the opportunity to run a rental unit without the need to purchase and maintain a second property
  • Providing supplemental income through ADU rent
  • Providing a separate living space for people who wish to live independently but may require some caregiving or support
  • Allowing for multigenerational family options that include privacy, yet proximity
  • Increasing property value
  • Allowing property owners to downsize to the ADU while renting out the main house

ADUs benefit renters by:

  • Providing access to rental housing in single-family and high-demand areas
  • Providing diverse and affordable housing options
  • Providing the opportunity for multigenerational living
  • Using less energy for heating and cooling, reducing energy bills
  • Preserving community connections through the densification of established neighbourhoods

ADUs benefit the environment by:

  • Increasing densification, in turn decreasing urban sprawl
  • Requiring fewer resources to build and maintain compared to full-size homes and traditional large-scale multi-unit dwellings
  • Using less energy for heating and cooling, reducing carbon emissions
  • Increasing housing availability near areas of employment, thereby reducing carbon emissions from commuting
  • Minimizing environmental impact by utilizing existing infrastructure and services

ADUs benefit communities by:

  • Minimizing visual impact to a neighbourhood compared to the addition of a traditional large-scale multi-unit dwelling, such as an apartment building
  • Promoting more compact and walkable communities
  • Filling the housing gap for seniors, people with disabilities, and newcomers in the housing market
  • Increasing housing availability near areas of employment
  • Facilitating multigenerational living
  • Preserving community connections through the densification of established neighbourhoods
  • Increasing tax revenue while not adding any new infrastructure or services, in turn, providing municipalities with the ability to add/invest in amenities in neighbourhoods 

Yes, generally ADUs need to be registered through a building permit and/or residential rental licensing program with the local municipality. However, the exact requirements and associated costs vary from municipality to municipality. Consult your local planning department for more information.

Although “ADU” and “tiny home” may sometimes be used interchangeably, there are distinct characteristics between the general definitions of these two housing alternatives. While ADUs are forms of permanent housing that exist in addition to a larger main dwelling unit on a lot, tiny homes are often the only residence on a small piece of property and/or are a mobile structure.

Although legislation may differ by province and municipality, in general, mobile homes are not classified as ADUs. Consult your local planning department for more information.

There are many sources where ADU designs can be found, such as independent companies that offer designs (and sometimes even building kits) for ADUs. Additionally, property owners can hire architectural firms to design a custom ADU for their space. Some municipalities also offer sample designs for reference. Visit the homepage for your municipality to see a list of industry partners and/or consult your local planning department to explore your options.

Property owners are generally restricted to building only one detached ADU on their lot. However, many municipalities may allow one detached and one internal or attached ADU to coexist on a single lot. 

In Ontario, changes in provincial legislation (Bill 23) indicate that you may be permitted to have both 1 internal/attached and 1 detached ADU. Consult your local planning department for more information.

Detached ADUs are generally assigned their own mailing addresses while internal and attached ADUs can often use the same mailing address as the main dwelling. However, these rules may differ from municipality to municipality. Consult with your local planning department for more information and to learn how to register a new address.

It depends. Lands within heritage conservation areas and properties listed as heritage buildings generally require special permitting before ADU development can take place. Consult your local planning department and heritage conservation authority for more information.

It depends. While some municipalities prohibit the construction of ADUs in floodplain areas, others allow for ADU construction under special permitting. Our tool tries to capture these additional requirements on a lot by lot basis. Consult your local planning department and environmental conservation authority for more information.

It depends. Typically, however, ADU development can take place with special permitting from the local environmental conservation authority. Our tool tries to capture these additional requirements on a lot by lot basis. Consult your local planning department and environmental conservation authority for more information.

Parking requirements (i.e. the number of spaces required per ADU, parking space dimensions, and acceptable space arrangements) vary widely from municipality to municipality. Although the tool’s user-input parking function provides the number of parking spaces needed to accommodate an ADU, due to barriers within the data, it cannot be determined if the existing driveway and/or garage already meets local ADU parking requirements. Consult your local planning department for more information and to confirm if your lot already meets the parking requirements.

You’ve started in the right place! You can use ADUSearch to determine if the lot allows for a detached ADU and if there are additional considerations at this time. From there, we suggest reaching out to your local municipality (Planning and Building Departments) to confirm the information and also the process to apply for a permit. Next, you will need a qualified designer (architect, builder, contractor) to determine a design that will be suitable for your lot. We also suggest reaching out to your financial institution to understand what lending options are available for your property, in order to be pre-approved.

See the homepage for your municipality for a list of industry partners and consult your local planning department to explore your options.

It depends. Generally, from start to finish (design, permit, build, occupancy), it can take 6 months to 1 year, depending on the municipality and availability of builders in your region. This process varies significantly across Canada, but as a rule of thumb, plan at least a year in order to budget for all the disruptions that could take place!

Building permit processes vary across municipalities. It usually begins with a preliminary review with your Planning and/or Building department before a formal application submission, so we would advise that you consult your local planning department for more information. Our Resources tab (above) could point you in the right direction too.

The cost of building an ADU can vary greatly depending on factors such as the location of your property, the type of ADU being built, the size of the ADU being built, and the choice of construction, interior materials, and design. As a rough approximation, ADUs can cost between $120,000 and $400,000 to build.

Adding an ADU to your property will result in an increase in property taxes. After construction of an ADU is complete, the entire property will be reassessed by the province’s assessment authority. The addition of an ADU would be deemed as an “improvement” to one’s property, and the assessment authority would therefore reassess the property at a higher value. However, the total tax impact, as well as the mechanisms for taxation, depend on the actual size of the ADU that was built, the municipal, education, and special rates being applied, the province where the property is located, and the availability of tax relief programs. Consult your local property tax department for more information about specific property tax implications and available tax-related relief programs. 

It depends. The total cost of an ADU can vary greatly depending on its size and design, the location (provincial and municipal) of the property, local permitting and application fees, developer charges, and assessment value impacts. On one hand, the market for ADU construction is relatively new in Canada, and developer charges can be high for early adopters. On the other hand, new legislation and programming across the country demonstrate endorsement for this housing option– which means there are a number of financing opportunities (as outlined below) that can help lessen the cost of permitting and construction. ADUSearch includes financial modeling layers that provide a high level illustration of property owner affordability based on estimated construction, utility, and tax costs.

As ADU development presents one solution to the issue of affordable housing supply, municipal and provincial governments across the country have begun offering incentive programs to encourage the uptake of ADU construction in their community. Refer to our Resources tab (above) for more information.

The National Minimum Regulation (NMR) applies a lenient set of zoning bylaw requirements for building detached ADUs on residential lots. Our team designed the NMR to conduct a baseline analysis in all cities to understand the maximum potential for building detached ADUs under a permissive policy scheme.

The Hypothetical Detached ADU Regulation (HDR) is a set of hypothetical bylaws for detached ADUs. Our team designed the HDR in consultation with ADU advocates from municipal planning services and the planning field to model the potential for detached ADUs in cities without existing regulations in Quebec.