Plan, Permit & Build Your ADU in Ontario
An accessory dwelling unit is a self-contained home on the same lot as your house, built for rental income, family, and long-term value. We provide full-service planning, design, and construction for every type of ADU across the province.
Ontario’s ADU Specialists
What Is an Accessory Dwelling Unit?
An ADU is a self-contained residential unit built on the same lot as a principal dwelling. Homeowners across Ontario use ADUs to generate rental income, house family members, and add long-term property value.
Our team handles zoning reviews, building permit applications, custom design work, and code compliance so your project moves forward without delays, from a compact basement suite to a standalone backyard build.
What We Handle
- Zoning & by-law reviews
- Building permit applications
- Custom ADU design work
- Ontario Building Code compliance
ADU Options
What Types of ADUs Can You Build in Ontario?
Ontario homeowners can choose from several types of ADUs depending on lot size, zoning, and budget. The most common options include:
Basement Apartments
A secondary suite built within the principal dwelling. Often the most cost-effective route to a legal rental unit when ceiling height and egress allow.
Garden Suites & Coach Houses
A separate building placed in the backyard. Garden suites must meet specific height and floor area limits set by your municipality.
Interior Conversions
Reworking an existing basement or attic into livable, code-compliant space. Typically the least disruptive option for a single lot.
Detached ADUs
A standalone accessory structure on the same lot, sometimes above a detached garage. Requires more setback space than an interior conversion.
Each dwelling unit is located differently based on your property layout and local zoning by-law. We confirm what your lot allows before any design work begins.
Our ADU Services
Full-Service Support From Concept to Inspection
We stay involved at every stage so your ADU build stays on track, on budget, and fully code-compliant.
Planning & Zoning Consultation
We analyze your local zoning by-law, assess property lines and setbacks, and identify which additional residential units are permitted, preventing costly surprises once building starts.
Building Permit Assistance
We prepare documentation, verify compliance with building code requirements, and submit applications to municipal authorities on your behalf, reducing approval timelines.
Custom ADU Design
We create plans that maximize floor area within allowable limits, integrate the new space with your main dwelling, and balance aesthetics with full building code compliance.
Code Compliance & Safety Reviews
We review ceiling heights, plumbing and HVAC, fire separation, and ventilation so every self-contained dwelling meets Ontario Building Code safety benchmarks.
Project Management
From concept through final inspection, we coordinate contractors, run on-site evaluations, and provide ongoing support to keep your build on schedule.
Why Build an ADU
A Versatile Way to Expand Without Buying a Second Property
ADUs have grown in popularity since updated legislation made them easier to permit. Many municipalities now actively encourage owners to build through streamlined programs and pre-approved designs.
Rental Income
A self-contained residential unit generates steady monthly cash flow on land you already own.
Property Value
A well-built additional dwelling boosts resale appeal and appraisal numbers.
Additional Housing
ADUs help address the housing shortage by adding density to existing residential lots.
Family Flexibility
House aging parents or adult children in a private, accessible space on your own property.
The Process
Building an ADU, Step by Step
Five clear stages take you from confirming eligibility to handing over the keys.
Zoning Review
Confirm your lot is eligible and check by-law requirements for setbacks, coverage, and permitted structure types.
Design & Planning
Work with our team to create a plan that meets building code requirements and your personal goals.
Building Permit
Submit the application with all required drawings, site plans, and documentation for municipal approval.
Construction
Build the dwelling to code, with inspections at each key milestone to keep quality on track.
Final Inspection & Occupancy
Pass the final review, then move in your tenant or family member.
Service Area
ADU Planning & Construction Across Ontario
We work with homeowners in every major Ontario city. Not sure if we cover your area? Send us your address.
FAQ
Frequently Asked Questions
Common questions about building an accessory dwelling unit in Ontario.
What is an ADU?
An ADU is a self-contained dwelling unit that includes a kitchen, bathroom, and sleeping area. It functions independently from the principal dwelling and can be attached or detached. These units are built to meet strict safety, size, and livability standards under the Ontario Building Code.
Are ADUs permitted across Ontario?
Yes. Provincial legislation allows ADUs in most zones, though building code rules can vary by municipality. Check your local zoning by-law before starting. Whether you plan a detached build or an addition to an existing dwelling, verify what your lot permits first.
Do I need a building permit for an ADU?
Yes. Every additional dwelling unit requires a building permit. The application process involves submitting architectural drawings, site plans, and proof of code compliance. Our team handles this paperwork so you can focus on the project itself.
What are the minimum standards for an ADU?
The building code sets out minimum standards for size, safety, structure, and systems. Each dwelling unit requires a private entrance, independent kitchen and bathroom, proper ventilation, fire separation between living areas and the rest of the house, and compliance with gross floor area limits. Plumbing, electrical, and heating systems must also meet current code.
How much does it cost to build an ADU in Ontario?
Costs depend on the type of unit, location, and scope of work. A basement apartment conversion typically costs less than a new detached structure. Factors include materials, labour, permit fees, and site preparation. Contact us for a detailed estimate based on your property.
Can I add more than one ADU to my property?
Some municipalities allow both a secondary suite inside the house and a detached garden suite on the same lot. Others limit you to one ADU per property. Review your local by-law or contact us for guidance on what your zone permits.
Does an ADU increase property value?
Yes. A well-designed additional dwelling unit adds flexible living space that appeals to buyers, renters, and multigenerational families. In most Ontario markets, ADUs deliver strong returns through both increased property value and rental income potential.
Guides & Resources
Learn the Rules Before You Build
In-depth guides on Ontario ADU types, zoning, permits, and costs, written for homeowners, not contractors.
What Is an ADU?
A complete guide to accessory dwelling units in Ontario.→
Additional Residential Units
ARU rules, as-of-right zoning, and the 2026 build process.→
In-Law Suites
What an in-law suite is and how it differs from a secondary suite.→
Are In-Law Suites Legal?
Rules, permits, and costs for a legal secondary suite.→
Basement Apartment Requirements
Ceiling height, egress, fire separation, and the code basics.→
Garage Conversions
Turn an existing garage into permitted, livable space.→
Ready to Start Your ADU Project?
Contact us today for expert guidance on building an accessory dwelling unit in Ontario. We confirm your ADU options, estimated costs, and timeline so you know exactly what your property can support.