September 30, 2026

What a Garden Suite Costs in Toronto in 2026, Line by Line

A garden suite in Toronto costs the builder’s price plus everything that never appears on it. The builder’s number covers the building. It usually does not cover design, survey, permits, servicing the suite from the street or the house, landscaping, financing, or the money you should set aside for what turns up once the ground is open. This article adds up the whole budget.

We don’t give a single per-square-foot number. No public, independent source publishes one for garden suites, and the figures on builder websites vary mostly because each builder decides differently what is “in” the number. What follows gives you the City’s actual fees, the line items to price, and the questions that turn three different quotes into three comparable ones. (You’ll also see garden suites called ADUs, the American term. In Ontario, the terms that matter are garden suite, laneway suite and additional residential unit.) If your lot backs onto a public lane, it falls under Toronto’s laneway suite rules instead; our guide to building a laneway house in Toronto covers what they allow.

The short answer

Think of the total cost of a garden suite as five layers:

1. Construction: the building itself, the foundation, the finishes and the site work the builder has agreed to do.
2. Design and approvals: the architect or designer, the survey, engineering, and the permit.
3. Connecting the suite: water, sewer, hydro, heat and any work in the yard or the lane to get them there.
4. Charges and financing: development charges (or their deferral), the interest on money borrowed to build, and legal fees.
5. Contingency: money held back for things nobody can price yet.

Builder quotes usually cover layer 1 and part of layer 3. Layers 2, 4 and 5 sit with you, and layer 3 is where quotes disagree most. If a number you’ve seen looks low, check which layers it includes before you compare it to anything.

What drives the price of a garden suite

Some of these are choices and some are set by your lot, which tells you where you have room to move.

Size and shape

The kitchen and bathroom cost about the same whether the suite is small or large, which is why small suites tend to cost more per square foot than large ones, and why a per-square-foot figure quoted without a size attached tells you very little. A simple rectangle with a plain roof costs less to frame and less to insulate than a building with jogs and cutouts. A second storey adds stairs and structure, but it also lets you fit more floor area on a small footprint.

Toronto’s zoning rules allow two-storey garden suites where the setback and separation requirements are met, and basements are permitted (City of Toronto, Garden Suites). A basement is a real cost decision. Digging costs money, and in much of the city you’ll be thinking about groundwater, drainage and how the suite drains to the sewer.

Access and the yard

Getting materials to the back of the lot is part of the price. A lot with a side passage wide enough for a small machine is a different job from one where everything is carried through the house. Ask each builder how they plan to get the excavation, concrete, lumber and drywall to the back, and whether the plan is in the quote or left as an assumption.

The City also requires access for emergency services from the street, with a maximum 45-metre travel distance and a minimum width of 1.0 metre (City of Toronto, New Garden Suite). On a deep, narrow lot, this can decide where the suite goes before any design work starts.

Foundation, trees and finishes

Foundation type depends on soil, groundwater and nearby tree roots, none of which shows on a drawing, so ask your designer whether a geotechnical opinion is warranted. The City asks for a Tree Declaration Form on any project that could damage private or City trees. Finishes have the widest spread of all: ask each builder to price against the same written finish schedule, with named allowances for anything not yet selected.

An allowance is a placeholder for something you’ll pick later, and it’s often where a low quote gets its price. We cover this in how to read a construction estimate.

The owner’s budget, beyond the construction price

This is the table most builder quotes leave out. It lists the items an owner budget should hold. We haven’t put dollar figures against the items the City doesn’t publish. Get a quote for each, and write down who supplied it and when.

Set this up as a spreadsheet before you talk to builders and fill it in as quotes arrive. An empty line tells you what to ask about next.

What the City actually charges for the permit

For 2026, the permit fee is calculated as a service index multiplied by the floor area in square metres. The service index for single-family dwellings, which is where garden suites sit, is $18.56 per square metre. There’s a minimum fee of $214.79, and each new residential unit in an application adds $56.33 (City of Toronto, Building Permit Fees).

As an illustration of the arithmetic only: a suite with 60 square metres of floor area (about 645 square feet) would carry a permit fee of 60 × $18.56, or about $1,114, plus the $56.33 unit fee. The City also charges $92.79 an hour (2026) for examination and inspection activities beyond the base fee, so treat that figure as the floor. Fees are reviewed each year, so check the current schedule when you apply.

The drawings behind the permit cost far more than the fee. An application needs a site plan or survey, fully dimensioned floor plans, elevations and sections, a roof plan, a lot grading plan, an Application to Construct or Demolish, an energy efficiency design summary, designer information, a tree declaration form and a plumbing data sheet where applicable (City of Toronto).

Development charges

Development charges are what a municipality levies on new development to pay for the infrastructure that growth uses. For garden suites, the picture has changed over the last few years, and it’s worth confirming with the City before you budget.

The City’s garden suites page says By-law 1137-2022 exempts the second through fourth residential units on a single parcel from development charges, and that garden suites are exempt from parkland dedication where the parcel holds up to five units (City of Toronto, Garden Suites). On a lot with one house, a garden suite is the second unit. The City’s development charges overview also lists an exemption for the second to sixth unit in developments of up to six units, effective July 24, 2025, and refers to a separate deferral program for laneway and garden suites (City of Toronto, Development Charges Overview).

Which rule applies depends on what’s already on your lot. Where the deferral program applies, the terms are these: the charge is deferred for 20 years from the date the building permit is issued, and it becomes payable earlier if a new lot is created through a plan of subdivision, plan of condominium or consent to sever, or if the property is sold without the buyer signing an assumption agreement. Applying involves a deferral agreement and a restriction registered on title, and the City says its review takes 15 to 20 business days. The City’s instruction is blunt: do not pay the development charges up front, because it can’t credit the fee back (City of Toronto, DC Deferral Program).

So the budget line for development charges is one of three things: nothing, a deferred amount that doesn’t affect your cash now but does affect a future sale, or a real cost. Ask the City which applies to your property, in writing, before you finalize the budget. If you’re adding units to the main house as well, our guide to building a multiplex in Toronto explains how a garden suite counts alongside a fourplex.

Servicing

The City’s guidance says a garden suite’s water and sanitary connections are “intended to connect from the primary dwelling” (City of Toronto). That can be much less work than a separate street connection, and it also means the suite’s demand lands on the house’s existing pipes. Your plumber should confirm the house’s service line size and condition before anyone commits to the plan. Old lead or undersized lines, or a sewer lateral in poor shape, turn a simple tie-in into a replacement.

Hydro is the item owners forget. A new dwelling unit may need a larger panel, a new service to the house, or a separate feed to the suite. Ask an electrician to look at the existing service and tell you what the load calculation says before the design is finished. The same goes for natural gas, if you’re considering it.

The Province’s guide says municipal approval for connections depends on water and sewage capacity in your area, and that you’ll need to speak to your municipality about whether the suite can be serviced through the primary house (Ontario, Building a laneway or garden house).

Contingency

Contingency is your money, held by you, for problems the drawings can’t show. On a garden suite, the largest unknowns sit underground and inside the existing house’s services, so the contingency is properly larger at the start and shrinks as the foundation and rough-in are completed and inspected.

We’ve written about how to size it in how much contingency is enough. The right amount depends on what you know when you set it. A suite with a geotechnical report, a scoped service upgrade and a fixed-price contract needs less than one where none of those exist. Don’t put a percentage from the internet into your budget without asking what it assumed.

Financing

Most owners finance a garden suite from the equity in their house. The federal government’s mortgage insurance rules changed in January 2025 to allow insured refinancing for secondary suites. Under CMHC Refinance, lenders can lend up to 90 per cent of the home’s value after the work, where that value is under $2 million, amortized over up to 30 years; an amortization beyond 25 years carries a 0.20% premium surcharge. The property can have up to four units, one of which must be lived in by the borrower or a close family member rent-free, and the new suite must be self-contained, comply with local by-laws, and not be rented for periods under 90 days (CMHC Refinance; Department of Finance Canada).

Your lender will lend against the finished value but pay out in stages against progress, so you’ll carry some costs (design, permits, the deposit) yourself before the first draw. The interest on the money you borrow during construction is part of the cost of the project, and a longer build means more of it. Talk to a mortgage broker or your bank before you sign a construction contract, not after, so the draw schedule in the contract matches the way the lender pays.

Fixed price or cost plus

The contract structure decides who carries the risk of the unknowns, and for a small building it decides how much you’ll pay attention to the project once it starts.

Fixed price (stipulated sum)

The builder agrees to build a defined scope for a defined price. The price only holds if the scope is defined, which means you need complete drawings, a finish schedule and clear allowances. If the drawings are unfinished, a fixed price is only fixed on paper, and the difference shows up as change orders. The standard Canadian forms for this are the CCDC 2 for larger work, and for small residential work many builders use their own form or a residential form from a builders’ association. Whichever you use, have a lawyer read it.

Fixed price works best when the design is complete, the site conditions are reasonably known, and you don’t expect to change your mind.

Cost plus

You pay the actual cost of labour, materials and subtrades, plus a fee, which can be a percentage or a fixed amount. You carry more of the risk of cost overruns and you also keep the savings if things go well. Cost plus can be a sensible fit when the design isn’t finished or when the site is uncertain. It works only if you get reporting: a budget, a monthly cost report, copies of the invoices behind every charge, and a cap or a target price if the builder will agree to one.

The fee structure matters too. With a percentage fee, the builder’s fee rises as the cost rises; with a fixed fee, it stays put whatever the cost. Both are common, and you should know which one you signed.

Our piece on five questions to ask before you sign works through what a contract should say on changes, schedule, payment and disputes. Every one of those applies to a garden suite contract.

Holdback in plain terms

Ontario’s Construction Act requires an owner to hold back 10 per cent of the price of the work from each payment to the contractor, for a period after the work is finished. The purpose is to give people who have not been paid (a subtrade, say) a source of funds, and the way they claim against it is a construction lien on your property.

In practice, it works like this. Each time you pay the builder, you keep back 10 per cent. When the work is substantially performed (broadly, ready for use, with only a small amount left to finish), a certificate of substantial performance is issued and published, and anyone owed money on the job has 60 days from that point to preserve a lien. Once that period has passed with no lien preserved, you pay out the holdback (Construction Act, R.S.O. 1990, c. C.30). Amendments in force from January 1, 2026 also require holdback to be released each year on contracts that run past their first anniversary, which a slow garden suite build can do (Ontario Bar Association, 2026).

Holdback applies even where the contract doesn’t mention it, so settle it before the first payment. Ask your lawyer to confirm the holdback mechanics for your contract and how they interact with your lender’s draws. Ask the builder to confirm in writing that subtrades and suppliers are being paid, and ask for that confirmation with each payment application. And keep the holdback somewhere you won’t spend it. The Act also sets rules on how quickly a proper invoice must be paid; ask your lawyer to explain the payment timelines so that the draw schedule and the invoice routine agree.

Where garden suite budgets drift

Most budget movement on a small build comes from the same few places, and most can be asked about before you sign.

Underground and unseen. Excavation finds fill, rock, a buried oil tank or a drain nobody had drawn. Ask the builder what the price assumes about the soil, and what the rate is per extra cubic metre if the assumption is wrong.

The house’s services. The tie-in to the house turns up a lead line, an undersized panel or a cracked lateral. Have the plumber scope the sewer with a camera, and the electrician do a load calculation, before design is finalized.

Allowances. A quote with generous allowances for kitchen, tile and lighting can look low. Ask for each allowance in dollars, and compare them to what you would actually choose.

Scope that sits between trades. Who supplies the trench for the hydro feed, who patches the wall, who restores the lawn? If two builders list different exclusions, the cheaper one may simply be leaving something out. Ask for a written list of exclusions.

Changes you make. A change once the framing is up costs more than the same change on paper, because it means undoing work. Decide the things you care about (outlet locations, window sizes, kitchen layout) while it’s still paper. Our article on where change orders come from covers this in more depth.

An owner can see most of this early with three habits. Get a written budget with the layers above. Ask for a monthly cost report against that budget, and read it. And put any change, however small, in writing with its price before the work goes ahead.

Timeline from idea to occupancy

We’re not going to give you a total number of months, because it depends heavily on how long design takes, whether you need a variance, and the season you start in. What we can give you is the sequence, and the City’s stated review times for the steps it controls.

1. Confirm the lot works. Check zoning on the City’s interactive map, emergency access and the location of any trees. A Zoning Applicable Law Certificate is recommended before you apply for a permit, and an application is treated as incomplete without one where it’s required (City of Toronto).
2. Design and drawings. Duration depends on your designer and how quickly you decide.
3. Committee of Adjustment, if needed. Only if the design needs minor relief from zoning rules. This adds its own application, notice and hearing, and our guide to the Committee of Adjustment in Toronto sets out each step, the fees and the timing.
4. Building permit. Garden suites are reviewed in Toronto Building’s House Stream, and the City says complete applications there are reviewed within 10 business days (City of Toronto, Review Streams). Incomplete applications have no review time frame, which is why the checklist matters.
5. Development charge deferral, if it applies. The City says its review takes 15 to 20 business days, and it can run alongside the permit.
6. Contract and financing. Line up quotes, choose the contract form, and settle the lender’s draw schedule. This step tends to be slower than people expect.
7. Construction. Ask your builder for a dated schedule that shows the sequence: excavation, foundation, framing, rough-in, inspections, insulation, finishes.
8. Final inspections and occupancy. Inspections are booked through the City, and the suite can’t be occupied until they pass.

The City’s clock runs only while a complete application is in its hands. The rest of the calendar is yours.

Questions to ask a builder

Bring these to every builder you interview.

1. What is in your price, and what is not? Can I have the exclusions in writing?
2. Is the price fixed, cost plus, or a mix? If it’s a mix, which parts are which?
3. What do you assume about the soil, and what happens to the price if the assumption is wrong?
4. Who arranges and pays for the water, sewer, hydro and gas connections, and who is responsible if the house’s services need upgrading?
5. What allowances are in the price, and how much is each one?
6. How do you price and approve changes? Will I see a written price before the work happens?
7. What is your payment schedule, and how does it work with holdback and my lender’s draws?
8. Who are your key subtrades, and how do you confirm they’ve been paid?
9. What is the schedule, in dates, and what do you do when it slips?
10. Which inspections do you arrange, and who attends?
11. What does the warranty cover, and who do I call?
12. Can I speak to two owners of small builds you’ve completed in the last two years?

The warranty answer deserves care. Ontario’s new home warranty, administered by Tarion, covers freehold, contract and condominium homes, and Ontario’s guide notes that Tarion requirements do not apply when an existing building is renovated to create a dwelling unit (Tarion; Ontario). Whether a detached suite built for an owner who already holds the land is enrolled depends on how the build is structured. Ask the builder directly, ask for the answer in writing, and if in doubt call Tarion. Whatever the answer, the contract should say what the builder warrants and for how long.

When it makes sense to bring in outside help

A garden suite is a small building, but it puts a homeowner in the position of an owner running a construction project: setting a budget, choosing a contract, approving payments and deciding what to do when the news isn’t good. Many owners do it well with a good builder and a lawyer who reads the contract. Others find that the budget, the contract and the schedule are where they’d like someone who has done it before. That’s the part of the work we do: we help owners set the budget, compare quotes on the same basis, review the contract before it’s signed and keep an eye on cost and progress through the build. To be clear about our experience, Myhal hasn’t delivered a garden suite. Our 20+ years and $3B+ of delivered work, built at PCL Constructors and Oxford Properties, are on larger projects, and the disciplines carry over: a written budget, a comparable set of quotes, a contract that says what changes cost, and regular reporting. If you’d like a second opinion on a quote or a contract before you commit, our development management work is the place to start, or you can get in touch and tell us what you’re planning.

Frequently asked questions

How much does a garden suite cost in Toronto?

The total depends on size, site conditions, finishes and how the servicing works out on your lot. Builder-published ranges cover only part of the cost. Build your own total from the budget table above: design, survey, permits, servicing, landscaping, financing and contingency, alongside the builder’s price, using written quotes for each.

How much is the building permit for a garden suite in Toronto?

For 2026, the City calculates the permit fee as $18.56 per square metre of floor area, with a $214.79 minimum, plus $56.33 for each new residential unit. Hourly charges for examination and inspection can apply on top. The fee schedule is updated annually, so check the current one before you apply.

Do I pay development charges on a garden suite in Toronto?

Usually not. The City says By-law 1137-2022 exempts the second through fourth residential units on a parcel, so a garden suite behind a single house is normally exempt. The City also runs a 20-year deferral program for laneway and garden suites. Ask the City to confirm in writing which applies to your lot before you finalize the budget.

How long does it take to get a garden suite permit?

The City says complete applications in its House Stream are reviewed within 10 business days. It doesn’t include the time to prepare drawings, obtain a variance or answer comments, which usually takes longer than the review itself.

Should I choose a fixed-price or cost-plus contract?

Fixed price suits a complete design on a well-understood site. Cost plus, with monthly reporting and a target price, can suit an unfinished design or an uncertain site. Many small builds do best with a mix: fixed for what can be defined, unit prices for what depends on the ground. Have a lawyer review whichever you choose.