Accessory Apartment: Egress Window/Door

Question Icon
Posted by: from Whitby
10/15/2020 at 12:08:13 PM

I just bought my first home in Whitby, Ontario and will be taking possession later this year. I'm both excited and terrified.

I'm investigating the cost/effort that will be required to complete the basement as a legal accessory apartment and would like to verify my interpretation of the requirements

-One means of egress is required. If I have an egress door, I don't need an egress window.

-Bedrooms must have a window area at least 5% of the rooms floor area, but do not have to be egress windows.

-Provided that an egress door opens into a living/dining room, the window(s) on the door(ie.patio door), count towards the requirement to have 10% window area of the living.

-Egress windows/doors have a minimum size requirement.

Thanks in advance!


User Icon
Carsten from KM&C Homes in Kingston
Date/Time10/15/2020 at 2:08:40 PM

Hi Dave,

Yes that is correct on the egress info, but you also need to consider fire rating, which means you need a fire separation between the two units, ie. Fire rated door, fire rated drywall and ductwork needs to have a fire stop and all holes need to be filled with fire rated caulking so there is a fair bit of things to consider when having a unit in the basement.

Thank you,


Chief Operation Officer

KM&C Homes

User Icon
Richard in Edmonton
Date/Time10/15/2020 at 6:07:53 PM

All bedrooms require an egress window unless the suite is sprinklered. The window must be minimum .35 m2 (3.75 sq. ft.) in unobstructed area (when in the open position) with no dimension less than 380 mm (15").

You will want to have a typical 2'8" door to the exterior and to living areas not only for egress but also for moving furniture.

I don't believe there's a requirement for % of window area for living spaces or bedrooms unless there's a day-care operation in the basement - unless the Ontario Code is different than the National on this point. A long time ago there was such a requirement.

User Icon
Date/Time10/15/2020 at 10:58:06 PM

Hi David,

in Ontario you need to have a glass space in rooms according to type and size of the room,

however if the house is more then 5 years old you can have an architect ask to grandfather it and cut the in half,

you can have 2.5% for a bedroom and 5% for the living room.

if you planing on a door, then it will be at the basement floor level (?) and that means you need to reinforce the foundation with under pining of foam if your city allows it,

the cheaper option i to do an Egress window, this window sill must be cut at least 48" from the floor and have sizes as you said,

you have to conform with the city about the window style since they do not agree to all off them. (not all cities are the same).

if you need a well you need to connect it to the weeping tile,and there are rooles for the wells

thank you

Harry C.

User Icon
David in Whitby
Date/Time10/16/2020 at 9:57:44 AM

Thanks Carsten, I wasn't aware of the fire rated caulking. I'll be sure to take a closer look at the requirements for fire separation.

Thanks Richard, seems like there's some disconnect in building codes at the provincial vs national level. How would we know which takes precedence?

Thanks Harry, for the heads up on the possibility of grandfathering in on the window size. As well as noting some of the key steps for installing an egress door at basement floor level.

I've been learning about the process of putting in egress door/window out of personal interest, however I would definitly be bringing in a professional for the job.

For my city, I believe the window styles are flexible, as long as the escape clearances are maintained. Both in the window opening and the window well. I will definitely be taking a closer look.

The property is 29y/o (built in '91).

I am considering one of two solutions for the egress requirement. Whichever is more cost effective. My preference would be the basement floor level door.

1. Egress door at basement floor level.

2. Egress window in the living. Plus a side entry door at ground level added to an existing common area (stairs) with appropriate fire separation.

Thanks everyone,


User Icon
Dave from 360renos in Ottawa
Date/Time10/17/2020 at 8:38:59 AM

Morning Dave

The Ontario Building Code takes precedence over the national.



Dave Bennett

Owner - 360renosInc.

User Icon
Richard in Edmonton
Date/Time10/17/2020 at 12:02:23 PM

Regarding Building Codes; all Canadian Codes are based on the National. Some provinces/territories adopt the National without change and some make minor revisions (additional requirements) before calling it their own.

Again unless the Ontario Code is different than the National it's not required to have a fire-separation for a secondary suite (which carries a rating and would require fire-rated drywall); rather it's more of a fire stop or fire block which is unrated and requires only regular drywall plus a solid core door at the suite entry. Also the furnace room must be enclosed on the inside with drywall and all joins need to be sealed (i.e. around ductwork/penetrations, etc). Air cannot be mixed from one suite to another (2 furnaces). Here in Edmonton there are builders building new homes with secondary suite included so the required construction details can be viewed.

If you're digging on the outside to install exterior stairs and a door to the basement you may be compromising a Code rule which requires footings to be minimum 4' below grade for frost protection. Of course you will have to start with development and building permits and you may encounter other difficulties.

User Icon
David in Whitby
Date/Time10/19/2020 at 10:06:12 AM

Thanks all for the valuable information!

Search the TrustedPros directory and discover the best contractors in your area.

Find your home service pro
Great renovations start with a great contractor.

Since 2004, TrustedPros has been helping homeowners find the right contractor for their home improvements and repairs.

Post Your Project

Within hours you'll be comparing offers from top-rated professionals. It's free to post and you're under no obligation to hire.

Trustedpros Inc. does not warrant the accuracy, completeness, safety, legality or usefulness of any Content, or Whether Content is Current and up-to-date, and TrustedPros Inc. Shall have no liability whatsoever with respect to your use or reliance upon any content or for content being removed or otherwise ceasing to be available. Please refer to the terms and conditions of use of this websites for more details.

Get quotes from top-rated contractors