Key takeaways
| Question | Short answer | Source |
|---|---|---|
| Public figures | The guide separates City-published cost data from a Modular X quote. | Public data and caveats |
| Site drivers | Servicing, access, foundations and electrical upgrades affect the site-specific budget. | Site cost drivers |
| Local fees | Permit fees, development charges and incentives differ by municipality. | Municipal fees |
| Financing | CMHC Refinance eligibility must be confirmed with the lender. | Financing and incentives |
| Lot-first budget | Modular X provides a project-specific budget after a feasibility review. | Where Modular X fits |
What the public data says a garden suite costs
The most detailed public cost figures in Ontario come from Toronto. In May 2025, Gladki Planning Associates reported to the City of Toronto on how its garden suite rules were working, and the City published the report with its final monitoring report. Four figures from that work are useful for budgeting. Each comes with a caveat, and each is shown with its source.
| What was measured | Figure | Source and caveat |
|---|---|---|
| Estimated construction cost on Toronto garden suite building permits, 2022 to April 2025 | Average about $260,000; median $180,000 | Garden Suites Zoning By-law Review and Monitoring Report (May 2025), section 5.1.1. Permit estimates may be under-reported for fee calculation, and some records include work on the main house |
| What architects, builders and consultants told the City's consultants | Actual costs often exceed $300,000–$400,000 | Same report, section 5.1.1. Can be significantly higher where servicing is complex |
| Industry estimates recorded in stakeholder interviews | $200–$300 per sq ft; total $400,000–$500,000 | Attachment 5 to the City's final report, Community and Stakeholder Engagement Details. Interview notes, not audited costs |
| Electrical upgrade where a pole transformer is needed | Around $50,000 | Attachment 5, interview notes on electrical service |
Read together, permit-declared costs sit well below what the industry reports. The same report puts the average garden suite on those permits at about 82 m² of gross floor area, with a median of 68 m².
These are Toronto figures. We found no comparable published cost data from other Ontario cities. Treat them as a reference point, not a price for your lot, and not a Modular X quote.
What moves the number on your lot
The same City work names the costs that push a garden suite past the median:
- Servicing connections. Underground trenching, sewer and water separation and hydro upgrades can add substantial cost and complexity (Monitoring Report, s. 5.1.1).
- Electrical capacity. Existing service often lacks the amperage. In the interviews, three units plus a garden suite needed a 400-amp service (Attachment 5).
- Plumbing access. Costs can be high where connecting to adjacent lines is difficult (Attachment 5).
- Rear-yard access. Challenging site access increases overall project expenses (Attachment 5).
- Two storeys. Two-storey garden suites cost more overall than single-storey designs (Attachment 5).
- Code requirements. A garden suite must meet the same life safety, fire separation and building code requirements as a principal residence (s. 5.1.1).
Trees, grading and the fire access path are set lot by lot. Our lot check flags them before anyone draws a plan.
Permit fees and development charges, city by city
Fees are small next to construction, but they vary, and some cities waive or refund them. This is what each city publishes, checked in October 2026:
| City | What the city publishes |
|---|---|
| Toronto | By-law 845-2025: development charges are not imposed on a second, third or fourth residential unit, and the parkland dedication exemption covers one unit ancillary to the house, "which includes laneway and garden suites", within the by-law's unit limits |
| Mississauga | Building permit fees for additional residential units are refunded automatically once the unit is built and all inspections are complete. A garden suite also pays $81.90 plus HST for a new address, and the City's page says development charges apply to garden suites; its Gentle Density Table of Incentives (April 2026) lists City, Regional and GO Transit development charges as exempt for a second or third unit. Line by line: Mississauga garden suite fees and charges |
| Brampton | A $530 fee plus a $5,000 security deposit, a $200 registration fee and a $2,004.10 permit fee, per the City's Garden Suite Registration Process page |
| Burlington | The ARU Incentive Program, which offered fee waivers and forgivable loans, closed to applications on 1 October 2025. Education Development Charges set by the Halton school boards may apply to detached ARUs. Details: garden suite rules and approvals in Burlington |
| Milton | Every ARU must be registered with the Town for $340 per unit, with an inspection and a yearly renewal that has no fee during the three-year pilot launched in 2025. Details: garden suite registration and servicing rules in Milton |
| Hamilton | An additional dwelling unit may be subject to parkland and development charges; applicable fees are set during permit review |
| Markham | Every garden home and coach house must be registered with Markham Fire and Emergency Services after construction; the City says there is a fee for the inspection and registration |
Fees change. Confirm the current schedule with the city when you apply.
Financing and incentives that exist in 2026
- CMHC Refinance for secondary suites. Owners can refinance to fund a self-contained secondary suite: up to 90% loan-to-value for up to four units, an as-improved value below $2,000,000, and up to a 30-year amortization. The owner or a close relative must live in the home, the suite cannot be rented for less than 90 consecutive days, and CMHC approval is needed before construction or at an early stage. Ask your lender whether a detached garden suite on your property qualifies.
- Canada Secondary Suite Loan Program: not happening. It was announced in the 2024 Fall Economic Statement. Budget 2025 says the program, which was not yet operational, will not be implemented. There is no federal secondary suite loan to apply for. Full status and alternatives: Canada Secondary Suite Loan Program explained.
- Multigenerational Home Renovation Tax Credit. For the 2025 tax year, the CRA lists a refundable credit of 14.5% on up to $50,000 of qualifying costs, a maximum of $7,250, when the secondary unit lets a senior or an adult eligible for the disability tax credit live with a qualifying relative. Full guide: Multigenerational Home Renovation Tax Credit explained.
- Hamilton's ADU grant: closed. Hamilton's Additional Dwelling Unit and Multi-Plex Housing Incentive Program offered 70% of eligible costs, up to $40,000 per unit, in the Housing for Hamilton Community Improvement Project Area. The City says it has reached its funding capacity and the portal is closed to new submissions.
This page makes no promise about rent or returns. A suite's financing case depends on your mortgage, your lot and your plans for the unit.
Where Modular X fits
We do not publish a price list, because the lot sets the number. A feasibility check confirms zoning, servicing distance, trees, access and crane reach first, and then we price your property. City detail: Toronto garden and laneway suite cost, Mississauga garden suite cost, and the city pages for garden suites in Burlington, garden suites in Milton, Hamilton, Markham and Vaughan. Build method: modular vs site-built.
Frequently asked questions
Public cost data is thin outside Toronto. Toronto building permits filed from 2022 to April 2025 declared an average estimated construction cost of about $260,000 and a median of $180,000, according to a May 2025 report prepared for the City. Industry experts interviewed for that report said actual construction costs often exceed $300,000–$400,000. None of these is a Modular X price; a feasibility check prices your lot.
Industry experts interviewed for the City of Toronto's 2025 garden suite monitoring work put typical costs at $200–$300 per square foot, with total costs of $400,000–$500,000. Those are interview figures recorded by the City's consultants, not audited costs.
The City's consultants say permit estimates may not reflect actual construction budgets and may be under-reported for fee calculation purposes. Some permit records also include work on the main house.
It depends on the city. Toronto's By-law 845-2025 says development charges are not imposed on a second, third or fourth residential unit, within the by-law's conditions. Hamilton says an additional dwelling unit may be subject to parkland and development charges, set during permit review. Mississauga refunds permit fees for additional units but says development charges apply to garden suites. Confirm with your city before you budget.
No. It was announced in the 2024 Fall Economic Statement, but Budget 2025 says the program, which was not yet operational, will not be implemented. CMHC's insured refinance for secondary suites is the federal option that exists.
CMHC Refinance lets owners refinance to build a self-contained secondary suite: up to 90% loan-to-value for up to four units, an as-improved property value below $2,000,000 and an amortization of up to 30 years. The owner or a close relative must live in the home, the suite cannot be a short-term rental, and CMHC approval is needed before construction or at an early stage. Your lender confirms whether your project qualifies.
The Multigenerational Home Renovation Tax Credit. For the 2025 tax year, the CRA lists it as a refundable credit of 14.5% on up to $50,000 of qualifying costs, a maximum of $7,250, when the secondary unit lets a senior or an adult eligible for the disability tax credit live with a qualifying relative.
Hamilton's Additional Dwelling Unit and Multi-Plex Housing Incentive Program offered a grant of 70% of eligible costs, up to $40,000 per unit, in its Housing for Hamilton Community Improvement Project Area. The City says the program has reached its funding capacity and the application portal is closed to new submissions.
Sources
- Gladki Planning Associates for the City of Toronto — Garden Suites Zoning By-law Review and Monitoring Report (May 2025), Attachment 4 to PH23.1
- City of Toronto — Attachment 5 to PH23.1, Community and Stakeholder Engagement Details
- City of Toronto — By-law 845-2025 (development charges and parkland, 24 July 2025)
- City of Mississauga — Additional residential units
- City of Brampton — Garden Suite Registration Process
- City of Burlington — Additional Residential Unit Incentive Program
- Town of Milton — Register an Existing ARU
- City of Mississauga — Gentle Density Table of Incentives (April 2026)
- City of Hamilton — Additional Dwelling Units (ADU)
- City of Hamilton — Additional Dwelling Unit and Multi-Plex Housing Incentive Program
- City of Markham — Coach Houses and Garden Homes Guide for Homeowners (April 2026)
- CMHC — Refinance for Building Secondary Suites
- Government of Canada — Budget 2025, Annex 3 (Canada Secondary Suite Loan Program)
- Canada Revenue Agency — Multigenerational Home Renovation Tax Credit (line 45355)
Municipal rules, fees, and programs change. Confirm current requirements with the city at application. Modular X provides exact pricing only after a site-specific feasibility review.
Keep reading
Disclaimer: Figures cited are market estimates provided for information only and are not a quote. Municipal rules, fees, and programs change — always verify current requirements with your local authority. Modular X provides exact pricing only after a site-specific feasibility review.