Build Your Backyard Dream Home Across Ontario
From garden suites in Toronto to laneway houses in Ottawa, ADU Ontario helps homeowners design, permit, and build accessory dwelling units that add income, space, and long-term value to their property.
Permit-Ready Plans
Plans engineered to municipal ADU by-laws
Ontario-Wide Coverage
GTA, Ottawa, Hamilton & beyond
Fast Turnaround
Design to permit in 6–10 weeks
Custom + Modular
Site-built and prefab ADU options
Transparent Pricing
Fixed quotes — no hidden costs
ADU Options
Every Type of Accessory Dwelling Unit in Ontario
Ontario’s As-of-Right ADU rules now allow up to three residential units on most lots. Here’s how homeowners are making it work — and which option fits your property best.
Garden Suites
Detached backyard homes built from the ground up. Ideal for larger lots, multigenerational families, and rental income in Toronto, Ottawa, and suburban Ontario.
Learn More →Laneway Houses
Perfect for homes backing onto a public laneway — especially in downtown Toronto and older Hamilton neighbourhoods. Compact, modern, and high-yield.
Learn More →Basement Apartments
Legal secondary suites carved out of existing basements. The fastest and most affordable way to add a rental unit while keeping your home intact.
Learn More →Garage Conversions
Turn an attached or detached garage into a fully-permitted living space. Lower site prep costs mean a faster path to move-in ready.
Learn More →Prefab & Modular ADUs
Factory-built units delivered and installed in days, not months. A weather-proof option with predictable costs for Ontario’s short build season.
Learn More →Attached Additions
Expand your primary residence with a legally-separate second unit sharing a wall. Great for tight urban lots where every square foot counts.
Learn More →Why ADU Ontario
Ontario’s Most Complete ADU Resource
We handle every step from feasibility study to final inspection — or give you the tools to navigate it yourself.
By-Law Experts
We track zoning and ADU by-laws across every Ontario municipality, so your project stays compliant from day one.
End-to-End Service
Design, engineering, permits, and construction under one roof. No hand-offs, no finger-pointing when issues arise.
Free Feasibility Review
Send us your address and we’ll tell you exactly what you can build before you spend a dollar on design or surveys.
Financing Guidance
From CMHC’s Secondary Suite Loan to HELOCs and construction mortgages, we’ll walk you through what actually works in Ontario.
Service Area
ADU Planning & Construction Across Ontario
We work with homeowners in every major Ontario city, and our guides cover by-laws for dozens more.
Blog
Learn Before You Build
Our in-depth guides cover Ontario ADU rules, costs, and design decisions — written for homeowners, not contractors.
What Are Accessory Dwelling Units?
Start here for the basics: what counts as an ADU under Ontario’s residential planning rules, the main types Ontario homeowners are building, and how they differ from secondary suites and rental units.
Read More →Are In-Law Suites Legal in Ontario?
The short answer is yes — but the rules vary by municipality. We break down what makes an in-law suite legal in Ontario, what permits you’ll need, and where the common pitfalls hide.
Read More →What Makes a Basement Apartment Legal in Ontario?
Ceiling heights, egress windows, fire separation, parking — here’s the practical checklist of what your basement apartment needs to meet Ontario Building Code and become a legal second unit.
Read More →Ready to See What You Can Build?
Send us your property address for a free, no-obligation feasibility review. We’ll confirm your ADU options, estimated costs, and timeline within two business days.