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5 Signs of an Illegal Basement Apartment

In our previous post "Is Your Basement Apartment Legal? In this post, we provide a guide to spotting illegal basement apartments. We highlight 5 red flags that can help you identify them. Additionally, we offer further details on these signs to assist you in your search.

To discuss, why they are obvious points for illegal basement apartments. We will be leaning more toward the technical side of the Ontario Building code

In the section below we will explore Part 9 and Part 11 of the Ontario Building Code. The building code has two parts. Part 9 applies to new or existing houses under 5 years old. Part 11 applies to houses over 5 years old.

5 Red Flags of an Illegal Basement Apartment

1. Ceiling height under 1950mm, including ductwork and beams.

For a house that is less than 5 years old

The minimum height for the ceiling is 2300 mm over at least 75% of the required floor area with a clear height of 2100 mm at any point over the required area,

Reference Ontario Building Code Ceiling Heights of Rooms or Spaces

For a house that is past 5 years old

In detached houses, semi-detached houses, townhouses, and row houses containing not more than two dwelling units,
(a) Minimum room height shall not be less than 1 950 mm over the required floor area and in any location that would normally be used as a means of egress, or
(b) minimum room height shall not be less than 2 030 mm over at least 50% of the required floor area, provided that any part of the floor having a clear height of less than 1 400 mm shall not be considered in computing the required floor area.

Reference Ontario Building Code Part 11 C102 - Ceiling Heights of Rooms or Spaces

In Summary, if your house is more than 5 years old and no more than 2 dwelling units then the absolute minimum height is 6'-5" or 50% of the room cannot be less than 2 030mm and the other 50% can be less than 2 030mm and any area that is less than 1400mm will not be included in the required floor area.

From the latter building code we quoted, the ceiling height can be less than 1 950mm, however, we will need to also consider the minimum height for a mean of egress required by code is 1 950mm according to OBC Part 11 C127. Therefore this concluded if your basement has a ceiling height that is less than 1 950mm, it is very likely to be illegal.

2. Absence of a separate entrance.

Separate entrance means gaining access from the side entrance, garage, or exterior basement walkout stairs. This access must be from the exterior to the basement apartment and must be separate from the main unit.

(1) Except as provided in Sentences (2) and (3), every dwelling unitcontaining more than 1 storey shall have exits or egress doors located so that it shall not be necessary to travel up or down more than 1 storey .......

Reference Ontario Building Code Travel Limit to Exits or Egress Doors

Part 11 of the Ontario Building Code, specifically C136 - 9.9.9, applies to houses older than 5 years. A separate entrance to the basement apartment is still necessary, although it is less strict.

3. Bedrooms or living spaces without windows.

Windows are one of the major requirements for Bedroom and living space. If there are no windows provided it is likely that the basement apartment is illegal. Please see the code reference below.

For a house that is less than 5 years old

Living rooms and dining rooms 10 % of the area served
Bedroom 5 % of the area served

Reference Ontario Building Code Minimum Window Areas

For a house that is past 5 years old

Living rooms and dining rooms 5 % of the area served
Bedroom 2.5 % of the area served

Reference Ontario Building Code Part 11 C107 - Minimum Window Areas

4. Lack of egress windows in the unit

According to the Ontario Building Code, every unit needs to have at least 1 egress window that provides direct access to the exterior (Reference Ontario Building Code Egress windows or doors for Bedrooms)

5. No smoke alarms in the bedrooms.

All bedrooms must have a smoke alarm, as stated in the Ontario Building Code (Reference Ontario Building Code We also want to emphasize that you should interconnect these smoke alarms. Illegal basement apartments often lack interconnected smoke alarms with the main unit, despite the possibility of having individual alarms.

Understanding and following the Ontario Building Code is important when checking if a basement apartment is legal. As we've discussed, the five key indicators – ceiling height, the presence of a separate entrance, window requirements for bedrooms and living spaces, the necessity of egress windows, and the installation of interconnected smoke alarms – are not just legal formalities but essential components that ensure the safety and habitability of a dwelling.

Following these standards is necessary for legal and safety reasons. It doesn't matter if your property is new or old. If you own a home or plan to rent one, knowing these rules can keep you safe and avoid legal problems.

It also ensures your living space is secure and meets the required standards. A legal basement apartment must meet building standards and provide a safe, livable, and secure home for all.


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The content provided above is intended solely for informational and reference purposes. It is crucial to consult your local municipality's building permit department for accurate and specific information pertaining to your circumstances.

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