Garden suites in the Greater Toronto Area cost between $250 and $750 per square foot to build, depending on finish level, foundation type, and city. A typical 650 sq ft garden suite ranges from roughly $200,000 on the basic end to over $500,000 for a high-end build with full basement, separate utilities, and premium finishes.
Toronto by-law 88-2022 caps most garden suites at 60-65 m² (645-700 sq ft) of floor area, with a 4 m height limit and 1.5 m setbacks from rear and side lot lines. Other GTA cities have similar provincial Bill 23-aligned rules. Foundation type is the biggest cost driver after size: a slab-on-grade is cheapest, while adding a full basement adds $50-80 per sq ft of floor area.
Bill 23 (the More Homes Built Faster Act) exempts garden suites from municipal development charges, saving homeowners $20,000-$40,000 depending on city. That exemption is one of the strongest incentives for building a garden suite versus a typical addition, and most GTA cities apply it automatically when the project is registered as an Additional Residential Unit at permit time.
Frequently Asked Questions
How much does a garden suite cost in Toronto?
A typical 650 sq ft garden suite in Toronto costs $200,000-$400,000 for a mid-range build with slab foundation, full kitchen, one bathroom, and shared utilities. High-end builds with full basements, separate utilities, and premium finishes can exceed $500,000. Bill 23 exempts garden suites from development charges, saving an additional $25,000-$40,000 in Toronto. Our calculator above estimates total cost based on your specific build parameters.
What is the cheapest way to build a garden suite?
The cheapest path is a basic-finish, slab-on-grade build with a kitchenette instead of a full kitchen and a single bathroom. Avoiding separate utilities (sharing hydro and water with the main house) saves another $8,000-$15,000. A 600 sq ft basic garden suite at slab on grade can come in around $180,000-$220,000 in the GTA. Lot conditions like soil type, tree protection requirements, and access for materials can push this higher.
Are garden suites still exempt from development charges?
Yes, under Bill 23 (the More Homes Built Faster Act, 2022) garden suites and other Additional Residential Units remain exempt from municipal development charges across Ontario. The exemption is worth $20,000-$40,000 depending on the city. The exemption applies automatically when the project is registered as an ARU at building permit submission. Toronto, Mississauga, Brampton, and Vaughan all currently apply the exemption.
How long does it take to build a garden suite?
Garden suite construction typically takes 16-32 weeks from permit issuance to occupancy. Permitting itself adds 4-12 weeks before construction starts (depending on city, currently 4-8 weeks for compliant designs in Toronto under by-law 88-2022). Foundation work, framing, and envelope take 8-12 weeks; interior finishes, MEP, and inspections take another 8-16 weeks. Weather and site access can extend this on tight downtown lots.
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