ADU vs Garden Suite vs Laneway Home: What's the Difference?

Short answer: ADU is the umbrella term. Garden suites and laneway homes are both kinds of detached ADU. The real difference is where the building sits on the lot, whether it backs onto a lane, and what your city calls it.

If you're planning a home in your backyard, the label matters less than your lot. But the label decides which rules you read, so it's worth getting straight.

Quick comparison

What is an ADU?

An accessory dwelling unit (ADU) is a self-contained home on the same property as a main house, with its own kitchen, sleeping area, bathroom and entrance. US HUD describes it as a single habitable living unit with separate ingress and egress, subordinate in size to the main home, that can be added to, created within or detached from it.

That gives three basic types:

• Interior: a unit inside the main house, like a converted basement.
• Attached: an addition on the side or back of the house, or above an attached garage.
• Detached: a separate building in the yard. Garden suites and laneway homes are in this group.

In the US, "ADU" is the standard term almost everywhere. In Canada, "secondary suite" usually means a suite inside the main home, while ADU covers suites on the same property, including detached ones. The Province of BC uses exactly that split.

What is a garden suite?

A garden suite is a detached, self-contained home in the backyard of a property with a main house. The City of Toronto defines it as living accommodation in an ancillary building, usually in the rear yard but not on a public lane, separate from the main home. The City of Victoria describes it as a ground-oriented suite in the backyard of a single-family property.

Garden suites are often one storey, though that depends on local rules. Typical uses are housing for aging parents or adult kids, a rental unit, a guest suite or a caregiver's home. Depending on where you live, you may also hear backyard cottage, backyard suite, granny flat or guest house for the same thing.

What is a laneway home?

A laneway home (or laneway house, or laneway suite) is a detached home at the back of a lot that faces onto a rear lane. The lane is the defining feature. It gives access for residents, emergency services and utilities without going through the main house.

In Vancouver, a laneway house is only allowed alongside a single-family home, or one with a secondary suite, on a site served by an open lane, a corner site with lane access, or a site with a street at both front and back. Toronto defines a laneway suite as a self-contained unit in an ancillary building next to a public laneway. In both cities, the laneway home can't be split off and sold separately from the main house.

Other names you'll run into

Canada's housing agency, CMHC, found more than 50 different names for these units in municipal bylaws. The ones you're most likely to see:

• Coach house or carriage house: usually a detached unit, often over or beside a garage.
• Garage suite: a unit built above or into a detached garage.
• Granny flat or in-law suite: named for who lives there, not the building type.
• Backyard cottage or backyard home: a plain-English way of saying detached ADU.

So which one can you build?

Start with your lot, not the label.

1. Do you have a rear lane? If yes, your city may treat a backyard home as a laneway home, with its own rules on height, setbacks and parking. If no, look at garden suite or detached ADU rules.
2. What does your zoning allow? In BC, secondary suites and/or ADUs are now allowed in single-family zones province-wide, and many lots can have three or more units. In the US, rules vary by state and city, and many have loosened ADU rules in recent years.
3. How big, how tall and how close? Floor area, height, setbacks from property lines and distance from the main house usually decide which plan fits.
4. Can you service it? Water, sewer and power connections, plus fire and emergency access, are often the deciding factors.
5. Can the building get in? A finished modular unit needs a clear path and usually a crane. Without a lane, that can rule it out.

Rules change often, and they differ even between neighbouring cities. That's why BuildPanel handles permits for you: we review your lot and coordinate the documents, project professionals, submissions and responses to your permitting authority.

Where BuildPanel fits

The building doesn't change with the label. The same BuildPanel model can be a garden suite in one city, a laneway home in another and an ADU across the border, as long as it meets local rules.

• G15 Series: compact residential layouts, from studio to one-bedroom and two-bedroom, sized for backyards and tighter properties.
• G13 Series: a 13 ft wide platform for guest suites, garden suites and cabins.

BuildPanel ships as flat-packed, factory-built components that are assembled on site, so a garden suite without lane access doesn't need room for a crane to swing a finished box over the house. Every permitted BuildPanel home sits on an engineered foundation and is designed for the local building code, climate and snow load. BuildPanel handles the permits, whether your city calls it a garden suite, a laneway home or an ADU.

For a full-size family home, see the G29 Series, our full-width family platform.

Learn more about backyard homes, guest suites and rental units, or see how the system works.

Next steps

Browse the Plans to find a footprint that fits your yard, check the FAQ on permits, foundations and delivery, and contact BuildPanel with your property location. New to factory-built homes? Read What Is a Prefab ADU?

Frequently asked questions