Build a detached ADU or convert an existing detached building

Scope of work

• Build one or two additional dwelling units (ADUs) in a detached structure on an existing residential lot

Type of permit application for a new structure

• Residential Accessory Building, Detached Garage or Shed
• Sub type: Accessory Building with Apartment

Type of permit application to convert an existing structure or build an addition to an existing structure

• Residential Additions and Renovations
• Work type: Addition with Accessory Apartment

Submission requirements

The following is a list of documents required to be submitted with your application. Please ensure all your documents, including drawings and forms, are ready in PDF format before starting your online application.

• Survey or site plan showing the following dimensions/details:
  • All existing structures including the gross floor area (house, sheds, decks, etc.)
  • Proposed building with setbacks to property lines
  • Required parking spaces
  • Entry door location and 1.2 m wide unobstructed pedestrian access to the unit
• Drawings
  • Overall floor plans drawn to a recognizable scale including;
    • Room names and room sizes
    • Ceiling heights (including under bulkheads and over stairs)
    • Window sizes (rough opening, glass area, and size of openable portion)
    • Wall/ceiling finishes
    • Location of all plumbing fixtures (including kitchen layout)
    • HRV duct design
    • Total size of the unit measured to the outside of exterior walls
    • If there is more than one ADU in the building, fire separations must be indicated
  • Foundation plan
  • Radon Gas Mitigation – A full active sub slab depressurization (ASD) system and a soil gas barrier under the floor slab is required for residential structures with a building area (footprint) over 20 square meters. Drawings shall clearly indicate details associated with the full active sub slab depressurization system and soil gas barrier under the floor slab.
  • Floor and roof framing plan
  • Engineered roof truss layout signed by the designer (where applicable)
  • Elevations of all sides
  • Cross section of the building showing all floor/wall/roof assemblies
• Energy Efficiency Design Summary form completed by the building designer
• Site Servicing drawings completed by a BCIN designer, Architect or P. Eng. that include:
  • Location, size and type of material of the existing and proposed water and sewer lines from the property line to the house and from the house to the ADU
  • Location, size and type of material of the existing and proposed (if upgrading) laterals from the City main to the property line
  • Note: only one water meter per property so the connections from the house to the ADU must be after the meter.
• Plumbing fixture count sheet
• Schedule 1 form (can be uploaded as a PDF or see fillable form in step 5) – This will be filled out by your BCIN designer or alternatively you can take responsibility for the drawings being the owner of the property without meeting the qualification requirements. If you are taking responsibility as the owner of the property, complete sections A, B, C (description of work) and D with your basis for exemption from qualification and registration requirements being that you are the “owner”.
• Small Multi Unit Residential Registration Form for each unit, filled and signed by the registered property owner

If proposing exterior stairs, the following additional information is required:

• Location of stairs/landing – Include distances to property line(s) on the survey or site plan and floor plan.
• Exterior stair design – Indicate landings, stairs and thickness of concrete walls. One pour design is not permitted. Foundation walls must have proper footings. Footings must bear on undisturbed soil which would be at the same depth as the house footings.

Building Code requirements

The following tables outline minimum Building Code requirements for room sizes and minimum glass areas for windows serving those rooms.

Reference: Sections 9.5 and 9.7 of the Ontario Building Code.

Individual room dimensions

Combination rooms (open concept primary rooms, not including bathrooms)

Ceiling heights

A minimum ceiling height of 6 feet 5 inches is required in an ADU. A minimum of 6 feet 1 inches is permitted under bulkheads within the ADU (e.g. beams and ducts).

Building permit fees

Once your building permit application is deemed complete, you will be notified by email of the applicable fees to be paid. The fees must be paid before your application can be placed in order to be reviewed.

Please visit guelph.ca/building for the current fee schedule.

Inspection requirements

Once the building permit has been issued, construction can begin. The mandatory inspections are identified on the building permit. Please book an inspection through the Guelph Permit and Application System. Please allow 48 hours’ notice for inspections.

An electrical contractor inspection form must be submitted at time of the final building inspection (from a licensed electrical contractor or the Electrical Safety Authority), certifying the additional dwelling unit has been inspected and there are no visible fire or shock hazards associated with the electrical system. This report will be required for both new and existing additional dwelling units and is in addition to any other electrical permits, inspections or certificates that may be required.

Planning your project

If you feel that your project is too complicated to handle yourself, we recommend that you retain the services of a qualified designer to prepare your drawings and specifications.

Some elements or structures may need to be designed by an Architect or Professional Engineer.

All work indicated on your drawings must conform to the Ontario Building Code, City of Guelph Zoning By-law and all other applicable law.  If your proposal does not comply with the Zoning By-law, please speak with Planning Services (519-837-5616 or [email protected]) to discuss your options.

For more information

Building Services
519-837-5615
[email protected]