Basic Duplex Requirements (Ontario)

If you are still thinking seriously about duplexing a home, here is the basic requirements I learned.  This helped me when we were purchasing a home to evaluate the potential for duplexing a new place before even putting an offer on the house.

As I have said in previous posts, I chose to duplex my home in the City of Kitchener, Ontario (Canada).  This is pretty close to the standards in the Ontario Building Code, so I would assume most cities at least in Ontario would be similar to this.  Always check with your municipality to confirm what is needed before starting such a project.

If you are also in Kitchener, the city of Kitchener’s website should have a current list.  This is what I was given in late 2019.  Please remember to first ask your inspector for clarity on these points, as they essentially have final say, and every house is slightly different.

These are the major points to consider:

(1) Fire Separation: 

This part is huge.  When you duplex a home, any walls or floor/ceiling, that are shared, must meet a fire separation requirement. In Kitchener (Ontario) shared walls need 30 minutes of Fire Separation.  Shared Ceilings need 15 minutes.  In english?  Normal Drywall would cover you for 15 minutes on your ceiling (if your inspector approves this, technically they may still want to see Type X drywall); But you would need to put 5/8″ Type X Drywall (Fire Code Core) on your common walls.  This is a thicker drywall, it will give you at least 45 minutes of Fire Separation (so I was told by my inspector). It is 5/8″ thick (instead of the normal 1/2″), and much heavier than normal drywall.  It is interlaced with fibers to retard the spread of fire a little longer than normal drywall.  Now, you only need this on one side of the common wall to meet the fire code. So you will only need to rip up one side of the wall.  If you plan well, it means you may only need to renovate one apartment, not both.

Tip: If you are already ripping off drywall, take the time and add soundproofing while you re-drywall the wall, even just the basic pink insulation will help.  Also, if you can, seal any plumbing or wire holes with silicone to deter mice, and if you can, replace any copper water pipes with PEX pipe, as it makes much less noise. We wish we had done this.  

Heres an interesting point my inspector told me.  I was gutting my home to begin with, so I replaced all my common ceiling and walls with 5/8″ Type X Fire Code Core Drywall.  This gave me a 45 minute fire separation throughout the entire apartment.  He said, because I did this (increased the fire separation on my ceiling), I did not have to have Interconnected Smoke Alarms.  By this point I already had them interconnected and installed, but its a point to consider if you were trying to save some money on wire.

If you were to have any common doors in these shared walls, you would need to install a Fire Rated Door and Frame, and include a self closing device. These types of doors will have some sort of a rating plate.

(2) Furnace Room: 

Depending where your furnace room is, this can be the most difficult room to ensure fire separation.  If your secondary apartment is sharing a ceiling or wall with your furnace room, you will need to ensure it is completely protected with Fire Code Core Drywall.  This also means you need special Fire Code Rings around any pipes going thru walls, and possibly a Fire Damper in any ductwork going thru walls.  This can get very tedious, so have the inspector go thru the room with you and tell you exactly what he wants to see.  (This can save you lots of time and money, as he may not need every pipe and such protected.)

Now, if this fire separation is to difficult to achieve, there is another option, install a sprinkler system. Here is the catch, you will need a certified sprinkler installer to do this part.

Now, if your Furnace room in not touching any of your new apartment through common walls or ceiling, you do not have to do anything for fire separation!

However, in either scenario, if you share a furnace, you will need to get a HVAC Technician to install a Smoke Duct Detector in the air duct system (return air or supply air).  This is a special smoke alarm that needs to monitor your furnace, if it detects smoke, it needs to shut down the fans and gas valve of the furnace system.   The City will need a Letter from the Installer stating his liability that it is installed correctly.  This means a home owner cannot do this job themselves, unless you happen to have an HVAC Company too.

(3) Room Size Requirements: 

Yes there are requirements of what is defined as a bedroom and what a kitchen, etc.  Each type of room needs to be a minimum of what is below:

• Living Room – 145 ft²
• Dining Room – 75 ft²
• Kitchen (1 Bedroom unit) – 40 ft²
• Kitchen (2+ Bedroom unit) – 45 ft²
• Master Bedroom (without closets) – 105 ft²
• Master Bedroom (with closets) – 95 ft²
• Other Bedroom (without closets) – 75 ft²
• Other Bedroom (with closets) – 65 ft²
• Bathroom – big enough for all fixtures

Kitchener, not sure about every municipality, allows you to combine areas.  This is great, for example, if you don’t have a separate dining room, you can combine with your kitchen. Here is the requirements if shared spaces:

• Living Room (more than 1 bedroom) – 145 ft²
• Living Room (only 1 bedroom) – 118 ft²
• Dining Room – 35 ft²
• Kitchen (more than 1 bedroom) – 45 ft²
• Kitchen (only 1 bedroom) – 40 ft²
• Bedroom Area – 45 ft²

So lets do a few examples, you would combine something as follows: Say you have a 2 bedroom unit. You could have a combined living room + dining of (145 + 35 ft²) 180 ft².  Instead of having separate areas of 145 ft² and 75 ft² respectively.  Thats a saving of 40 ft²!

Or you could say have a Kitchen + Dining area, of (45+35 ft²) 80 ft².  Instead of having separate areas of (45+75) 120 ft², thats also 40 ft² saving of space.

And if you had only enough room for a Bachelor apartment, the minimum area is

• Living, Dining, Bedroom and Kitchen – 145 ft²

(4) Light Requirement: 

Each type of room in an apartment has a minimum Natural Light requirement.  This is another key factor in selecting or designing a duplex. You would need to get the square footage of your room, and then figure out the glass area of the window needed.  This would let in an amount of natural light for your room.

For a home less than 5 years old:

• Living and Dining Rooms – 10%
• Bedroom and other rooms – 5%
• Kitchen and Bathrooms – n/a (means you technically don’t need a window)

For an older home, more than 5 years old:

• Living and Dining Rooms – 5%
• Bedroom and other rooms – 2.5%
• Kitchen and Bathrooms – n/a (means you technically don’t need a window)

So, heres an example. You have a basement in your 1980 Raised Bungalow. You want to turn it into a duplex.  You have two basement windows on the side of the house. They are say, 16″ by 30″. Typical contractor grade basement window.  Would it work?  Measure the actual glass area, lets say its 11″ by 25″.  Divide it into feet. (11″/12 = 0.916; 25″/12 = 2.083) That gives you 1.90 ft² (0.916 x 2.083).  Minimum Natural Light Area needed in a room is 2.5% of your room square feet (or 0.025). If you were to make a bedroom and keep that window, it would need to be a maximum size of 76 ft² (1.90 ft² x 0.025).  (Any bigger and you need a larger window.) Now, what is the minimum area needed? Look back up and we see it would also be 65 ft² (with closets) or 75 ft² (without closets).  So we are good.  [Note: this works for a secondary bedroom, but your master bedroom would need a larger window].

How about Egress?  Thats our next example.

(5) Egress Windows: 

An egress window is an emergency exit.  The inspector told me, that each floor needs one Egress window.  There is a minimum size.  If you ordering a new window, tell the supplier that it needs to meet Egress requirements.  They will know what size this is.

Here is a great diagram.

How about our above example?  Our window in our 1980 Bungalow was 16″x30″.  Lets say it opens sideways, and is alittle less than half that width, so say its a 12″ opening.  Would this work for egress?  (12″ wide and 16″ high) No.  While it would work for Natural light above, it would not work for Egress.  However, you only need one Egress for the entire floor in Kitchener (check your local codes to be sure).  So if we, say, put the egress window in the master bedroom or even living room, then we would be fine.

For an Egress Window, a person needs to be able to fit through the opening.  But, if you already have to upgrade your window due to Natural Light Requirements, make sure to choose a design that allows for Egress Requirements.  We chose a Euro Style window, as it opened inward like a door, instead of a slider.  This maximized our Egress opening, while keeping the size of the window smaller.  Tip: Your master bedroom and living room window will always be larger, so try to make one of those your egress window.

Another thing to consider when choosing an Egress window, is the opening position.  Typically a basement window needs a Window Well, as the window is below grade level.  If your window opens outward, then you will need a larger Window Well area to escape. See the diagram below for the minimum sizes.

We chose a style of window that opened inward, this saved us in the space needed for a Window Well.

Tip: If you need to replace a window, try to keep the same width and make the height larger.  This means you will not need to order a new Lintel (the metal bar that goes across the top of your window opening.) Of course, if you need to add significant depth to it, it may require a larger window well.  So try to find a balance between needing a new Lintel and/or a new Window Well.

(6) Parking: 

You will be making a duplex.  Thus it is logical you need at least two parking spaces.  This is the minimum of course.  Kitchener sets the limit at:

• outdoor space: parking space must be a minimum of 2.6m (8.5 ft) wide by 5.5m (18 ft) deep
• indoor space: parking space must be a minimum of 3.04m (10 ft) wide by 5.49m (18 ft) deep

You can choose whether to park in tandem (one behind the other) or beside each other. Obviously you would multiply which ever requirement for the desired style of parking.

Interestingly, you could combine this with garage parking.  If you parked one car in the garage, and one outside, this would also count.  (As long as the garage is located at least 6m ( 19.5 ft) from the property line).

(7) Minimum Ceiling Height: 

This is 6’5″, at any place in the unit.  So measure your lowest point, likely where there is duct work or a beam, and see if you have enough clearance.  Some have had to dig out the foundation to make the space taller.  This can be a very expensive option.

(8) Water Shut Offs: 

You will likely need to install shut off valves for the hot and cold water on each apartment. This is to ensure that when the supply to one suite is shut off, the supply to the other suite is not interrupted. This may require some new plumbing, so consider the ease of separating the water pipes before hand.  (Once separated, you could install a type of water meter to record how much each unit uses if so desired too.)

(9) Electrical Panel: 

If you want to get fancy, you could setup the secondary apartment on its own separate sub panel.  This is not a requirement, but it would make it easier to monitor (using some sort of after market monitor system) or you may want to have the city set up a separate Meter one day for the secondary unit.  Either way, you will be adding several large sized appliances in this new unit.  It is best to have a 200 Amp Service Panel.  This allows you to create a 100 Amp sub panel for the new unit.  Remember, you will now need power for (2) two stoves; (2) two dryers; and possibly more things.  You may be able to get by on a 100 Amp Panel, but if you were to add on anything else to this, like say a hot tub or pool pump, or even an electric car charger, and you will definitely need a 200 Amp Panel.  Best to find a home that already is setup with the larger panel, however, if needed, you can have an Electrician upgrade your panel.

So there you go.  If you are shopping for a new home and want to duplex it, think about those main points.  Or if you are contemplating changing your existing home to a duplex, this is a great exercise to see if it is worth it.  If you want a few more points, keep reading.  Otherwise I hope that helped you make your decision.

The following points are not as important when selecting a possible house to duplex, but good points to remember when do the actual construction:

Smoke Alarms: 

Smoke alarms are required in specific areas.  The code states that each floor requires a smoke alarm.  It also says that all new bedrooms need their own smoke alarm.  (However, if the bedroom was not altered to make this duplex, you only need to ensure there is a smoke alarm outside the bedrooms in the hallway.

It also states that there be a Carbon Monoxide Detector adjacent to all bedrooms.

Here is an important part, that I never saw until I was at my final stage of inspection.  This fire alarm needs to have a visual component.  This means, a strobe light.  This is not a normal smoke alarm you buy at Home Depot.  Check a local Electrical Supplier, they usually sell to public as well as Contractors.  A unit in Ontario goes for around $115.  There is usually only 1 or 2 choices. Amazon has them too, but for alittle more money.

So, for our duplex, we had 5 floors, the top 2 floors were original.  The top floor had the original 2 bedrooms and bathroom, this floor we only needed a Smoke Alarm/CO Detector with Strobe light mounted in the hallway adjacent to the bedrooms.

One floor down in this same apartment, we needed again, only 1 Smoke Alarm for the floor (this was living room and kitchen).

Now, the last 3 floors were the new lower apartment.  The main floor of the lower apartment was the kitchen and livingroom, so it only needed one Smoke Alarm located in the center of the room.

The next lower level of the Lower Apartment, was a common room and bedroom, so here I needed one Smoke Alarm/CO Detector located outside the bedroom in the common area.  As well as a Smoke Alarm in the bedroom.

Finally, on the lowest level of the Lower Apartment, we had two bedrooms, a hallway, and bathroom.  We needed one Smoke Alarm/CO Detector in the hallway adjacent the bedrooms, and each bedroom also needed their own Smoke Alarms.

This put our total to 5 Smoke Alarms and 3 combo Smoke Alarm/CO Detectors.  (The price for a Smoke Alarm vs a Smoke Alarm/CO Detector was only around $3, so I bought all the same Combo units).

Bathroom Fans: 

minimum 50 cfm, vented to outside. If you need to construct a new bathroom for this apartment, keep in mind you will need a fan.

Supply and Return Ducts: 

drop to floor level if possible

Blocking on Main Bathroom: 

If you are renovating or constructing a new bathroom, the main bathroom needs to have stud blocking for future installation of grab bars adjacent to bathtub and also near the toilet.  You can use 2×4; 2×6; etc, or even 5/8″ plywood. or larger.  (Just not OSB board). You need to make sure of the following.

For the Bathtub:

• Starting at the control end of the bathtub, measure between 12″-18″ along the horizontal run of the tub.  Then, from there measure 36″ vertically.  You will need to put backing along this vertical 36″.
• Measure up from the rim of the bathtub 6″-8″, and make sure there is backing for 36″ horizontally.

For the Toilet (if your toilet is within 18″ from a side wall) :

• Measure 6″ from the front edge of the toilet bowl, and 30″ off the floor.  Now place stud material for 30″ up (vertical) from this point.
• Measure 30″ off the floor. Starting from the back of the toilet, and put stud horizontally for 30″.

For the Toilet (if you are not near a side wall):

• measure 6″ above the toilet tank, and put stud material for 28″ horizontally above the toilet (centered from center of toilet).

Minimum Hallway width: 

The minimum hallway width is 2’10”.  This is also a good thing to keep in mind if you need to do any renovating to either unit.  We needed to create an entire floor, as it was previously an open basement.  We separated it into several rooms and a long hallway.  So here it was necessary to know the minimum hallway width.  Also good to remember when looking at homes, or deciding if your current home can work for a duplex, is our next point.

Vertical Clearance Above Cooktop: 

Most Municipalities will have a similar point like this in their Building Code.  This is what the City of Kitchener says.  If you are moving around kitchen counters or need to install a new set, make sure to remember this.  Anything you put above the stove, or cooktop, needs to be minimum 30″ from the top of the tallest burner. (Technically if you are putting a metal hood above the cooktop you can make it 23 5/8″).  The next thing, is the side clearances.  Take your tape measure and measure 17 3/4″ on an angle from your burner outwards, this will show you where to run your cabinets to.  See the diagram below for a better visual of what I mean.