Garden Suite vs Bunkie vs Tiny Home: Where the Building Code Draws the Line
In Ontario the line isn’t the name, the price or whether it came on a truck. It’s floor area and plumbing. Ten square metres (about 107 sq ft) with no plumbing is not a “building” under the Building Code Act. Add a sink, or go bigger, and you need a permit. Add a kitchen, bathroom and bed, and it’s a dwelling unit with garden suite rules.
At a glance
Zoning applies to all of them, permit or not. Setbacks, height and accessory building limits still count.
A bunkie is a sleeping cabin with no kitchen. At 10 m² or less with no plumbing it needs no building permit, but zoning still applies. Over 10 m², or with any plumbing, it needs a permit. A tiny home with a kitchen and bathroom, on a foundation or parked on wheels, is a dwelling unit: it falls under the same rules as a garden suite.
Ten Square Metres and a Drain Pipe
The whole question turns on one definition. Section 1 of Ontario’s Building Code Act, 1992 says a “building” is a structure occupying more than 10 square metres, or a structure of 10 square metres or less that contains plumbing. If it isn’t a building under the Act, the Building Code doesn’t apply and no building permit is needed.
Ten square metres is about 107 sq ft. That’s an 8 by 13 foot floor, measured to the outside of the walls. A queen bed, a nightstand and enough room to stub your toe.
There is a second exemption that people mix up with the first. Since the O. Reg. 451/22 amendments, a storage shed up to 15 m² (161 sq ft) is exempt too, but only if it’s one storey, detached, has no plumbing and is used only for storage. Toronto’s when do I need a permit page spells it out. A shed with a bed in it is not a storage shed. Your 14 m² “shed” with a futon and a space heater is a permit you didn’t get.
No permit does not mean no rules. Toronto puts it plainly: even if a building permit is not required, the zoning by-law still applies. That means setbacks, height, lot coverage and the limits on accessory buildings. The wiring needs an Electrical Safety Authority permit regardless of size, and your town may limit how many accessory buildings you can have.
Garden Suite vs Bunkie vs Tiny Home: Five Backyard Buildings, Five Rulebooks
This is how the rules usually land. Your township’s zoning by-law can be stricter, so treat the zoning column as “check with your town”.
| Building | Kitchen / bath | Building permit | Zoning treats it as | Live in it year-round? |
|---|---|---|---|---|
| Bunkie, 10 m² or less | Neither | Not required (not a “building”) | Accessory building or sleeping cabin; setbacks and height still apply | No. It’s overflow sleeping, not a home |
| Bunkie over 10 m² | Neither | Required | Accessory building or sleeping cabin, if your zone allows one | No |
| Bunkie with a bathroom | Bath only | Required at any size | Depends on the by-law; plus septic or sewer review | Usually no |
| Backyard office or studio | Maybe a powder room | Required over 10 m² or with any plumbing | Accessory building | No |
| Tiny home on wheels, parked and hooked up | Usually both | Can be required: ontario.ca says a structure on wheels can be a building if it stays in one spot | Often a trailer, which many by-laws restrict; otherwise a dwelling unit | Only if zoning and the Code both say yes |
| Tiny home on a foundation | Both | Required | A dwelling unit: an ARU or garden suite | Yes, if it meets ARU rules |
| Garden suite / ARU | Both | Required | Additional residential unit | Yes. That’s the point |
Last checked October 2026 · Sources: Building Code Act, 1992, s.1, ontario.ca: Build or buy a tiny home, City of Toronto permit page
A Bunkie Is a Bedroom That Lives Outside
In cottage country a bunkie is where the teenagers sleep so the adults can hear themselves think. It shares the cottage’s kitchen and bathroom. That shared part is exactly what keeps it a bunkie and not a second dwelling.
Many shoreline and rural zoning by-laws have a specific category for it, usually called a sleeping cabin. As one example, the Township of Assiginack’s zoning allows one sleeping cabin per lot in its Shoreline Residential zone, up to 60 m², one storey, a maximum height of 4.5 m, and it says a sleeping cabin “shall not include food preparation facilities” (township summary). Other towns use different numbers. Some don’t allow sleeping cabins at all.
What turns a bunkie into a dwelling
Inspectors and by-law officers look for the same three things: a place to cook, a place to wash, and a place to sleep. A bar fridge and a kettle start the argument. A two-burner cooktop and a sink usually end it. Once a bathroom goes in, it’s a building at any size and the sewage has to go somewhere legal. On a septic lot that means checking the system can take the extra flow, through a designer like our partner SepticReplacement.ca.
If what you actually want is a place for your mother to live year-round, build that from the start. A bunkie converted into a dwelling later almost never meets the foundation, insulation, fire and exit rules without a teardown.
Small Doesn’t Mean Exempt
The province’s guide is blunt: “Despite their size or uniqueness, tiny homes are required to meet Ontario’s Building Code” (ontario.ca tiny home guide). And if you haven’t met local zoning, you won’t get the building permit.
On a foundation
A tiny home on a slab, piles or a frost wall is a house. On a lot that already has a house, it’s a second dwelling, which means it’s an ARU or garden suite under zoning. Same setbacks, same fire access path, same servicing questions as any garden suite. The only thing “tiny” changes is the material bill.
Factory-built tiny homes can use Ontario’s two-permit system, in place since January 1, 2022: the town where it’s built reviews the construction, and your town reviews zoning, siting, foundation and hook-ups. Ask the seller up front which permit they carry, and what’s left for you. That “what’s left” list is often foundation, site plan, servicing and heat loss, which is what our permit packages cover.
On wheels
This is where the ads get optimistic. Ontario’s guidance says a structure on wheels “can be considered a building if it is located on the same spot for a period of time”, and lists the things that push it that way: hooked-up services, exterior stairs and anchoring. If it needs a licence plate or can be driven, it’s likely not a building. But that doesn’t make it legal to live in. Many zoning by-laws restrict living in a trailer or RV on a residential lot, and some limit the number of days. Check with your town before you buy, not after it’s in the driveway.
Rule of thumb: wheels change how a structure is classified. They don’t change the septic, the hydro or the neighbours. If someone lives in it with a toilet and a shower, plan as if it’s a garden suite, because the town probably will.
The Home Office Nobody Sleeps In
A backyard office is the easiest of the lot, as long as it stays an office. At 10 m² or less with no plumbing, no building permit. Over that, a permit, but a simple one. Zoning treats it as an accessory building, so the accessory limits apply: height, setbacks and coverage. In many urban by-laws accessory buildings are capped well below the house height and kept close to the rear lot line.
Three things push an office into a different category, and we see all three:
- A powder room. Plumbing makes it a building at any size, and the drain has to reach the sewer or septic. That trench is often the most expensive thing on the job.
- A pull-out couch “for guests”. Sleep in it and a fire and exit review follows. Rent it on a short-term site and you’re now under your city’s short-term rental rules too.
- Building it to convert later. Smart, if you do it on purpose. Put it where a garden suite would meet setbacks and the fire path, build a real foundation, and rough in the services. Then the future permit is a renovation, not a demolition.
Bunkie, office or garden suite? Ask before you buy.
A 30-minute call with a builder who has done this since 1979: $149.99 + HST. Bring the kit link or the quote, and we’ll tell you what it’s legally going to be on your lot and what it’ll really cost to set down.
The Price Tag Is the Smallest Number
Prefab studios get advertised by the box price, and the box is the cheap part. In a 2024 roundup, Storeys listed one 225 sq ft studio from about $85,000 and a one-bedroom from about $249,000, with site prep and permits left to the owner. A finished detached garden suite in Ontario is a different animal: one March 2026 contractor cost guide puts them at roughly $275,000 to $650,000 depending on size, finish and site.
The gap between a bunkie and a garden suite isn’t really the walls. It’s what’s underneath and behind them:
Foundation
A bunkie can sit on blocks or piers. A dwelling needs a foundation designed for frost, which in Ontario usually means frost-protected or below the frost line. See foundation options.
Services
Water line, sewer or septic, and a hydro feed sized for heat and cooking. Trenching across a yard adds up fast. See servicing costs.
Heat and energy
A lived-in unit needs a heat loss calculation and an energy-compliant design. That work is done by a BCIN designer such as OntarioHeatLoss.ca.
Six Expensive Backyard Shortcuts
Measuring the inside instead of the outside
The 10 m² is the area the structure occupies. A cabin that’s 10 m² inside is over the line once you count the walls.
Adding the sink after the inspection
A structure of any size with plumbing is a building. A by-law complaint from a neighbour is the usual way this gets found.
Using the shed exemption for a bunkie
The 15 m² exemption is for storage only. Sleeping isn’t storage.
Buying a tiny home on wheels with no plan for where it lives legally
Classification aside, many by-laws restrict living in trailers. Ask the planner first, in writing.
Skipping zoning because no permit was needed
Setbacks and height apply to every structure. Moving a cabin 1 m back from the lot line costs more than placing it right.
Forgetting the insurer
Tell your insurer what’s out back and whether anyone sleeps there. An unreported sleeping building can complicate a claim. See garden suite insurance.
Want something someone can actually live in?
Then it’s a garden suite, and the lot decides what fits. Our $399 + HST lot report checks size, setbacks, servicing and the fire route, in 48 hours, credited toward plans or a build.
Bunkies, Tiny Homes and Offices, Answered
Do I need a permit for a bunkie in Ontario?
Not if it is 10 square metres (about 107 sq ft) or less and has no plumbing, because then it is not a building under the Building Code Act. Over 10 square metres, or with any plumbing, you need a building permit. Either way, zoning setbacks and height limits still apply, and the wiring needs an ESA permit.
Can I live in a bunkie year-round?
Not legally as a home. A bunkie or sleeping cabin is accessory sleeping space that relies on the main house for cooking and washing. Many by-laws ban food preparation in a sleeping cabin. If someone will live there full time, build it as a garden suite under your town’s ARU rules.
Is a 15 square metre shed exempt from a permit?
Only if it is a storage shed: one storey, detached, no plumbing and used only for storage. That exemption came in with the O. Reg. 451/22 Building Code amendments. A building used for sleeping or as an office does not get the 15 square metre exemption; for those the line is 10 square metres.
Is a tiny home on wheels legal in my backyard in Ontario?
It depends on your town. Ontario says a structure on wheels can be considered a building if it stays in one spot, especially with services, stairs or anchoring. Separately, many zoning by-laws restrict living in a trailer on a residential lot. Ask your planner, in writing, before you buy one.
Does a tiny home have to meet the Ontario Building Code?
Yes. The province states that tiny homes must meet the Building Code regardless of size. On-site builds and factory-built units both need permits, and since January 1, 2022, factory-built units can use a two-permit system between the building town and the receiving town.
Do I need a permit for a backyard office?
At 10 square metres or less with no plumbing, no building permit is needed. Larger, or with a washroom, it needs one. Zoning rules for accessory buildings still apply, and electrical work needs an ESA permit.
Can I put a bathroom in my bunkie?
Only with a building permit, because any structure with plumbing is a building. The drain must connect to the sewer or a septic system that can take the extra flow, and your zoning by-law may not allow it. A bathroom plus a kitchen makes it a dwelling unit with garden suite rules.
What is cheaper, a bunkie or a garden suite?
A bunkie, by a wide margin, because it skips the frost foundation, plumbing, septic or sewer connection, heat loss design and fire separation work. But they are not substitutes. A garden suite is a legal home; a bunkie is a spare bedroom. Price the thing you actually need.