Feasibility Check

Side Addition



These are units created by adding a new self-contained addition at the side of your house. To legally register a unit, there are some specific requirements you will need to meet. The city refers residents to this Ontario website for a detailed guide for checking these requirements. Before you review the information provided by the Ontario website guide, check out our checklist below as a starting point to see if your home is a candidate for this kind of suite. Remember to verify all code requirements with your local code, or hire a professional to do this for you!


Spatial Requirements

Check to make sure you have a room for an addition


Look up your property
Side and rear yard setbacks are specific to different neighbourhood zones. You can look up your property’s specific zoning regulations using this map.Here’s a video that explains how to use the city’s  map website. If you have trouble navigating, ask a professional for help!

Check the side yard setback
Once you locate your property on the zoning map, you can find a link to the zoning rules for your property. This will tell you the allowable setbacks and other regulations. You can also use a measure tool to check the size of the building or other dimensions. Here’s a video that explains how.


Check if you have space for a side addition
After you find your side yard setback requirement, find your side property line, measure the required setback distance from it, and then measure the distance from that point to your home. 

This last number is the distance you have to build within. If you’re going to make a stand-alone unit. If you only have 2 or 2.5 meters, you may be able to squeeze in some sort of micro unit. 3m is an ideal width to fit a more typical unit.  


Check for protected trees.

  • Are you in an area protected by the Ravine and Natural Features By-law? Check here.
  • Are there any trees over 30cm in diameter?

If your answer is yes to either of these questions, your trees require protection. Look up the required dimension for the required Tree Protection Zone around each trees New construction should stay out of this zone, otherwise you will need to apply for a permit to injure or remove your tree.You can find more information on tree protection zones, and permits for injuring or removing trees on the city’s website.



Can you put in windows?


Natural light is a necessity for housing. If your addition will block windows in the existing house, you may need to add new windows to replace them.

We recommend making sure at least 2 sides of your addition are at least 1.2m form the property line. This will make it easy for you to add windows. If your wall is closer to the property line, adding windows requires additional fire protection (like sprinklers or fire shutters) which can be expensive!

You may also need to provide a second exit through a window in your unit that is large enough for a person to get through and easily open without any tools.




Electric, Heating/Air, and Plumbing

Check your utilities


Check your electrical service

Step 1 - Check the existing electrical service on your electrical panel

Find the circuit box. Find the main cut-off switch—this is typically the biggest switch in the box. The cut-off switch often has the number of amps written on it. You will likely need a minimum of 100 amps.

Step 2 - Use the chart below to calculate the existing electrical capacity (Coming soon.)

Step 3 - Check how many units you can add based on the existing electrical capacity. (Coming soon.)

Verify the level of electrical service you will need with a licensed electrical engineer or electrician.


Cost Considerations


Check to see if there are existing windows. And if there is ample space outside of the windows, this space is needed for emergency exiting. The Ontario website noted above provides specific requirements for these windows, but an architect or designer can help design this precisely.

- unit access
- fire and sounds separation
- site work
- new construction


Case study



The side addition case study involves adding a distinct living unit by building a new structure connected to the side of the existing structure of the house. The only changes made to the existing building are to the adjoining side wall which now acts as the fire separation and unit demising wall. Unit access to the side addition exists off the front of the addition. Major considerations include allowable building area, construction implications, and plumbing.


Existing Floor Plans
Case Study Floor Plans




This website, including all data and information incorporated herein, is being provided for information purposes only and is not intended for and has not been approved for use for construction at any location. For certainty, The University of Toronto, John H. Daniels Faculty of Architecture Landscape and Design and LGA Architectural Partners provides no representation or warranty regarding any use of or reliance upon this website, including no representation or warranty that this website  complies with applicable laws (including any applicable zoning by-laws or building code requirements) and no representation or warranty that any cost estimates included in or based upon this website have been validated by the applicable market. Any use of or reliance upon this website by any person for any purpose shall be at such person’s sole risk and The University of Toronto, John H. Daniels Faculty of Architecture Landscape and Design and LGA Architectural Partners shall have no liability or responsibility for any such use of or reliance upon this website by any person for any purpose. Prior to any use of or reliance upon this website by any person for any purpose, consultation with a professional architect duly licensed in the applicable jurisdiction is strongly recommended.






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