Guide · ADUs
ADU rules in Clarington, in plain terms.
Clarington allows up to two additional dwelling units on a property. Whether you get two, one, or none is decided by where your land sits on the map, before anything about your house matters.
The map decides first
This is the step most people skip, and it is the one that can end the project. Clarington’s permissions are not uniform across the municipality. The same house plan is allowed in Bowmanville and refused on protected land a few concessions north.
Two units
Courtice, Bowmanville, Newcastle, Orono
Also the hamlets outside the moraine and the white belt. One unit inside a single detached, semi detached or townhouse, and a second in an accessory building.
One unit
Greenbelt and Oak Ridges Moraine
On the moraine, in prime agricultural and rural residential zones, one unit inside a single detached dwelling. In the Greenbelt, one inside the dwelling or inside an accessory building that already existed before 1 July 2017.
None
Protected land
Natural Core and Natural Linkage lands, floodplains, and Environmental Protection zones carry no ADU permission at all. No design solves this one.
The pre-2017 rule in the Greenbelt catches people out. A barn or detached garage that went up after that date cannot become a unit, however sound it is.
Garden suites and garage conversions
The separate building has its own set of numbers.
If the second unit is going in a detached structure, whether that is a garage conversion or a purpose-built garden suite, these are the constraints that shape the design before you draw anything.
Size and siting
● Floor area has to stay smaller than the main house
● Rear and interior side yards, 1.8 metres minimum
● Front and exterior side yards follow your zone
● Coverage capped at the lesser of 10% of the lot or your zone maximum
Height, and it is split
● 6.5 metres in agricultural and rural residential zones
● 5.25 metres in urban residential zones
● That gap is the difference between a comfortable loft above a garage and a single storey, so it is worth checking your zone before the design starts
Parking
Three spaces, and a front yard that still has to be a front yard.
The main house needs two parking spaces already, and every ADU adds one more on top. A house with one unit added is therefore parking three vehicles.
The catch is that at least 30% of the front yard has to stay landscaped open space. On a narrow urban lot in Bowmanville or Courtice those two rules pull against each other, and the parking layout ends up driving the whole site plan. It is worth solving on paper early rather than discovering it at permit stage.
Servicing
On a well and septic, the Region goes first.
On municipal water and sanitary services the second unit connects through the existing home, which keeps it simple.
On private servicing the sequence matters. A Durham Region Health Department permit has to be in hand before the Municipality will issue a building permit. Adding a dwelling unit changes the load the septic system has to carry, and if the existing bed cannot take it, that becomes part of the project rather than a surprise halfway through it.
On development charges. These are set by the Region and the Municipality, and how additional units are treated has moved with provincial housing legislation. Confirm the current position with both before you build a budget around it, because it is a large enough number to change whether a project makes sense.
The process
Four steps, in this order.
1. Confirm it is permitted. Clarington Planning will tell you whether your property allows an ADU and whether what you have in mind meets the zoning. They are at planning@clarington.net or 905-623-3379 ext. 2660. This call is free and it is the one that prevents wasted drawings.
2. Apply for the building permit. Building Services can be reached at buildingpermits@clarington.net or 905-623-3379 ext. 2310.
3. Book the inspections as the work goes. They are scheduled at stages, not all at the end.
4. Occupancy, then registration. Once the Building Inspector grants occupancy the unit is finished and registered with the Municipality. That registration is what makes it a legal unit rather than an unapproved one.
If the unit is already there
Plenty of houses in Clarington already have an apartment that predates the current rules. A unit established before 14 July 1994 needs an inspection for Ontario Fire Code compliance. If it passes, a compliance letter goes to Planning and Development Services. If it needs upgrades, those can require a building permit of their own.
This is worth doing before a sale or a refinance rather than during one. We have built more than 30 ADUs across Northumberland and Durham, and have been working in this region since 1999.
Frequently Asked Questions
How many ADUs can I build in Clarington?
+
Up to two on a property, but it depends entirely on where the property sits. In Courtice, Bowmanville, Newcastle, Orono, the hamlets outside the moraine and the white belt, you can have one unit inside the house and a second in an accessory building. On the Oak Ridges Moraine in prime agricultural and rural residential zones, and in the Greenbelt, it drops to one. On Natural Core and Natural Linkage lands, in floodplains and in Environmental Protection zones there is no ADU permission at all.
Can I convert my detached garage into an apartment?
+
In most of urban Clarington, yes, as the second of your two permitted units. The detached building has its own rules: its floor area has to stay smaller than the main house, rear and interior side yards need at least 1.8 metres, coverage is capped at the lesser of 10% of the lot or your zone maximum, and height is limited to 5.25 metres in urban residential zones or 6.5 metres in agricultural and rural residential ones. In the Greenbelt there is an extra condition, because the accessory building has to have existed before 1 July 2017.
How much parking does an ADU require in Clarington?
+
The main house has to already have two parking spaces, and each ADU adds one more. At the same time at least 30% of the front yard has to remain landscaped open space. On narrower urban lots those two requirements compete, and the parking layout often ends up setting the site plan.
What happens if my property is on a well and septic?
+
The sequence changes. A Durham Region Health Department permit has to be in place before the Municipality will issue a building permit. An extra dwelling unit increases the load on the septic system, so if the existing bed cannot carry it, upgrading it becomes part of the project. On municipal water and sanitary services the unit simply connects through the existing home.
We already have an apartment in the house. Is it legal?
+
If it was established before 14 July 1994 it needs an inspection for Ontario Fire Code compliance. Pass it and a compliance letter goes to Planning and Development Services. Fail it and the upgrades required may need a building permit of their own. It is far better to sort this out ahead of a sale or a refinance than in the middle of one.
What is the first thing I should do?
+
Call Clarington Planning at 905-623-3379 ext. 2660, or email planning@clarington.net, and confirm your property permits an ADU at all. It costs nothing and it is the step that stops money going into drawings for something the zoning was never going to allow.
Thinking about an ADU in Clarington?
Send us the address. We will tell you what the map allows on that lot before anyone talks about design.
Request a Free Estimate (905) 376-5585Keep reading
See our ADU and garage conversion service, our home additions, and the work we do in Clarington, Durham Region and Oshawa. More guides are in the guides section.