Additional Dwelling Units

This includes submitting a complete application with:

• Required drawings and documents
• Compliance with the Ontario Building Code
• Payment of the permit fee

• Inside your existing home (e.g., in a basement or attic), or
• Detached, as a separate building on your property (e.g., garden suite)

Here are some key requirements:

• House Age – Different rules may apply depending on how old your home is.
• Water Service – You may need to upgrade your water line if the plumbing load increases.
• Location in the House – ADUs can be on any level, but rules vary for basements, attics, or upper floors.
• Room Sizes – There are minimum sizes depending on layout (open concept or with walls).
• Ceiling Heights – Minimum height is required, especially in basements and attics.
• Windows – Must be included in living spaces. Size depends on the room’s purpose.
• Safe Exits – Must have safe ways to exit in case of emergency.
• Plumbing – Requires hot and cold water, a sink, toilet, shower or bathtub, kitchen sink, and laundry access (in-unit or shared).
• Smoke Alarms – Must meet CAN/ULC S531, include a flashing light, and be properly labeled.
• Carbon Monoxide Detectors – Required if you have a gas/propane furnace or an attached garage. Can be battery or electric.
• Heating and Ventilation – Shared furnaces are allowed, but you must install a smoke detector in the ductwork that can shut off the furnace in case of smoke.
• Fire Separation – Fire-resistant construction is required between the ADU and the rest of the house.
• Septic System (if applicable) – Must have enough capacity to support the added use.

Requirements for detached units include:

• Water Service – May need to be upgraded depending on total usage.
• Fire Department Access – Must be a clear path from the street at least 1 metre wide and 2.1 metres high.
• Footings and Foundations – Must follow Building Code standards.
• Room Sizes and Ceiling Heights – Must meet minimum requirements.
• Windows – Must meet size rules based on room use. Limits may apply based on how close the wall is to property lines or other buildings.
• Safe Exit – Requires a direct exit to the outside.
• Plumbing – Requires a full kitchen, bathroom, and laundry access.
• Smoke Alarms – Must meet CAN/ULC S531, be hardwired and interconnected, and include a flashing light.
• Carbon Monoxide Detectors – Required if there’s a fuel-burning furnace or an attached garage. Must be hardwired.
• Heating and Ventilation – Must follow Building Code and include an HVAC design by a qualified professional.

To apply, you must submit:

• A building permit application form
• The application fee
• Two sets of construction drawings by a licensed designer

Drawings must include:

• Site plan
• Foundation plan
• Floor plans
• Building elevations
• Cross sections and construction details
• Engineered drawings (if needed)

The Town of Essex uses Cloudpermit, an easy-to-use online system. With Cloudpermit, you can:

• Apply for building permits 24/7 from your phone, tablet, or computer
• Track your application and receive updates automatically
• Book or cancel inspections
• Communicate directly with staff
• Pay online using a credit card
• Submit changes to your permit if needed.

MPAC assesses additional dwelling units (ADUs) in Ontario by including them in the overall property assessment, just like any other structure on the property. This means the value of the ADU is factored into the total assessed value, which in turn affects the property taxes. Generally, an increase in assessment leads to an increase in property taxes. For further information on your assessment please reach out to MPAC at 1 866 296-6722

You may be eligible for an GST/HST rebate on the construction of your ADU. Please see GST/HST New Housing Rebate - Canada.ca for the criteria. We recommend consulting a public accountant or CRA if you have further questions.

No, Additional Dwelling Units are exempt from all Development Charges and

Parkland Fees.