What Is a Garden Suite?

A garden suite is a self-contained home built in the back yard of an existing house. It has its own kitchen, bathroom, living area and entrance, and it is a separate building rather than a unit carved out of the main house. In Ontario planning language it is the detached form of an additional residential unit (ARU); homeowners also call it a backyard suite, a garden house or a granny flat. Deomax designs and builds garden suites across Toronto and the GTA and carries the feasibility check, the design, the permit, the servicing and the construction on one contract.

Garden suite vs laneway house vs coach house

All three are the same kind of building: a small detached home behind the main house. The difference is the lot. A laneway house sits on a lot that shares a property line with a public lane and is entered from the lane. A garden suite sits on a lot with no lane behind it, so access runs down the side yard. Coach house and carriage house are older names for either one. If there is no lane behind your property, a garden suite is the option available to you. We explain the differences in laneway versus garden homes.

What a garden suite costs in Ontario

Two numbers decide the budget: the hard cost of the building and the soft cost of getting it approved. As a reference point, our published Mississauga garden suite pricing runs $350 to $600 per square foot depending on size, with soft costs (survey, drawings, engineering, permit fees) typically between $15,000 and $50,000 on top. Other GTA municipalities land in a similar band, and the spread between the low and high end comes down to five things:

Size and model. A studio is cheaper per project than a one or two bedroom suite, though the cost per square foot usually falls as the building gets bigger.
Servicing distance and trenching. How far the water, sanitary and hydro have to run from the house or the street, and what is in the way: trees, hard landscaping, grade change.
Foundation and site access. Whether an excavator can reach the back yard, or whether material has to be carried through by hand. Rear-lane lots are the cheapest to build on for this reason.
Soft costs. Survey, drawings, engineering, permit fees, development charges where they apply, and a committee of adjustment application if the design needs relief from the by-law.
Finish level. The same shell can be a rental-grade fit-out or a high-spec one.

Every quote we issue is priced off the real distances on your lot, not an average, and the exclusions are listed at quote stage rather than at change-order stage.

Lot requirements: what the rules turn on

Ontario opened garden suites up province-wide. Bill 23, the More Homes Built Faster Act, requires municipalities to permit up to three residential units on most serviced residential lots, and each municipality sets the detail through its own zoning by-law. Whether your lot qualifies comes down to:

Lot size and depth. Most municipalities set a minimum lot area and a minimum rear-yard depth before a detached suite is possible.
Setbacks and separation. Distance to the rear and side lot lines, and a required separation from the main house.
Height and footprint. A maximum height and a cap on how much of the rear yard the suite may cover.
Tree protection. Protected trees on or near the building footprint can move the building or require a permit of their own.
Servicing. Water, sanitary and hydro have to reach the back of the lot, and older service lines sometimes need upgrading first.
Fire and emergency access. A clear, unobstructed route from the street to the suite entrance, typically at least 1.2 metres wide and within a maximum travel distance from the road.

The approval path

Zoning check. Before anything is drawn, we confirm the zoning position for your actual lot: size, setbacks, height, coverage, access route, trees and servicing. Design work done before this step is design work you may pay for twice.
Design. Layout, elevations and the working drawings, sized to what the by-law allows rather than what looks good on paper. Some cities publish pre-approved plans; where they fit your lot they shorten the review.
Permit. We prepare and file the building permit application and carry it through the review comments. Some municipalities also want a site plan and a grading plan, and some run the design through a planning or urban design review before the building permit.
Servicing and site prep. Trenching for water, sanitary and hydro, excavation and the foundation. This is where budgets move, which is why it is priced off the real distance on your lot.
Build. Framing, envelope, mechanical, electrical, plumbing, insulation, drywall, finishes, kitchen and bathroom.
Inspections and handover. Trade and final inspections, the deficiency walkthrough, registration of the unit where the city requires it, and the paperwork you need before anyone moves in.

Realistic timeline from first call to occupancy

Plan the project in two halves. The approvals half (survey, design, permit application and any minor variance) is the longer and less predictable one, and it is where most of the waiting happens; municipal review times vary by city and by how complete the first submission is. The construction half is comparatively predictable once the permit is issued. Starting the drawings and the servicing investigation early is what shortens the total, not rushing the build.

What disqualifies a lot

These are the reasons a lot that looks suitable does not get a garden suite:

No compliant access route. Emergency access is the single most common reason a lot fails. If the side yard is too narrow or the walk from the street is too long, the by-law will not allow the suite without a variance.
Rear yard too shallow. Once the rear setback, the separation from the main house and the suite’s own depth are added up, many newer subdivision lots do not have the room.
Servicing that cannot be reached or upgraded. Lots where the sanitary line cannot be extended at a workable grade, or where the existing service cannot carry another unit.
Protected trees on the footprint. A tree permit can be refused, and a building cannot always be moved far enough to avoid the root zone.
Floodplain, conservation authority or heritage constraints. Lots regulated by a conservation authority, in a floodplain zone or on a heritage property face extra review, and some are excluded outright.
Lot too small or too narrow for the zone. Where a minimum lot area or lot width applies, there is no design that fixes it.

We tell you which of these applies before you spend money on drawings. That feasibility check is the first thing we do on every garden suite.

What you should ask any garden suite contractor

Have you built one in my municipality? Rules and review times are set locally. Toronto, Mississauga and Brampton do not run the same process.
Is the permit in your scope or mine? A quote that stops at construction and leaves you to file the permit is not comparable to one that includes it.
How is the servicing trench priced? Ask whether the quote assumes a distance. A long run to the rear of a deep lot is real money.
Who confirms zoning before design? Design work done before the zoning position is confirmed is design work you may pay for twice.
What does the contract exclude? Get the exclusions in writing at quote stage, not at change-order stage.
Can I see a certificate of insurance? We provide ours on request.

Where we build garden suites

Each city page carries that city’s own rules, lot patterns, costs and permit route: garden suites in Toronto, garden suites in Mississauga, garden suites in Brampton, garden suites in Etobicoke, garden suites in Scarborough, garden suites in Oakville, garden suites in Milton and garden suites in Guelph.

Worth reading before you commit: garden suite zoning by-laws, garden suite utility connections, how to price your garden suite for profit and the benefits of granny flats for homeowners and investors. Already have a garage you could convert instead? See garage conversions and our comparison of garage conversions vs garden suites.

Free in-home consultation anywhere in Toronto and the GTA. Call (647) 760-3999.

Garden Suite Questions, Answered

What does a garden suite contractor do?

A garden suite contractor builds a self-contained second home in the back yard, with its own kitchen, bathroom, sleeping area and entrance, detached from the main house. Beyond construction, the work is proving the lot is feasible, getting the design through zoning and the building department, and running water, sanitary and hydro to the rear of the property.

Does the contractor handle the building permit?

Deomax prepares and files the building permit application and carries it through the review comments. Some municipalities also require a site plan and a grading plan. Always check whether a quote includes the permit, because a construction-only quote is not comparable to a design-build one.

What decides whether my lot can take a garden suite?

Lot size and depth, setbacks and separation from the main house, height and footprint limits, the emergency access route, and servicing plus any tree or conservation review. Emergency access is the most common reason a lot that looks suitable does not work.

What should I ask before hiring a garden suite contractor?

Ask whether they have built one in your municipality, whether the permit is in scope, how the servicing trench is priced, who confirms the zoning position before design work starts, what the contract excludes, and whether they can provide a certificate of insurance on request.

Is a garden suite the same as a laneway house?

They are the same kind of building. The difference is the lot. A laneway house sits on a lot that shares a property line with a public lane and is entered from the lane. A garden suite sits on a lot with no lane behind it. If there is no lane, a garden suite is the option available to you.