If you're a GTA homeowner considering a garden suite, the first question is always the same: how much is this going to cost me?
We've built garden suites across the GTA, and we're going to share real numbers — not vague ranges — so you can make an informed decision.
The Quick Answer
A garden suite in the GTA typically costs between $350–400/sq.ft fully built in 2026. For a standard 500–600 sq ft one-bedroom unit, expect $180,000 – $250,000 with mid-range finishes and a slab-on-grade foundation.
These figures include design, permits, site prep, construction, mechanical, electrical, plumbing, and finishes. They do not include furniture, landscaping restoration, or upgrades to your main house.
Full Cost Breakdown
Here's where every dollar goes on a typical 550 sq ft, one-bedroom garden suite build:
| Category | Cost Range |
|---|---|
| Architectural Design & Engineering | $8,000 – $15,000 |
| Municipal Permits & Fees | $3,000 – $8,000 |
| Site Prep (excavation, grading, tree protection) | $8,000 – $20,000 |
| Foundation (slab-on-grade) | $15,000 – $25,000 |
| Framing, Roof & Exterior Envelope | $35,000 – $55,000 |
| Mechanical (HVAC, HRV) | $12,000 – $20,000 |
| Electrical (panel, wiring, fixtures) | $10,000 – $18,000 |
| Plumbing & Water/Sewer Connection | $12,000 – $22,000 |
| Insulation & Drywall | $10,000 – $15,000 |
| Interior Finishes (flooring, kitchen, bath) | $25,000 – $50,000 |
| Exterior Finishes (siding, windows, doors) | $15,000 – $30,000 |
| Servicing (water, sewer, hydro connections) | $10,000 – $30,000 |
| Total Estimate (550 sq ft) | $193,000 – $238,000 |
Foundation: The Biggest Variable
A slab-on-grade foundation is the most cost-effective at $15,000–$25,000. A full basement under your garden suite adds $40,000–$70,000 but also adds livable square footage.
Finishes: Where Budgets Stretch or Shrink
Interior finishes are the most controllable cost. Our advice: spend on the kitchen and bathroom — that's what tenants and appraisers notice.
Costs by City
| City | Permit Fees | Key Notes |
|---|---|---|
| Toronto | $3,000 – $8,000 | Dev charges waived for garden suites |
| Markham | $2,500 – $6,000 | Coach houses allowed on larger lots |
| Mississauga | Waived | Free pre-approved plans, $44M CIP |
| Richmond Hill | $2,500 – $5,000 | May require water service upgrades ($15K–$30K) |
| Vaughan | $3,000 – $6,000 | Zoning review required |
Mississauga offers waived permit fees, free pre-approved floor plans, and the $44 million Community Improvement Plan. If you own property in Mississauga, you're starting with a significant cost advantage.
Hidden Costs Most People Miss
1. Water & Sewer Service Upgrades
Some cities require you to upgrade your existing water service line. In Richmond Hill, upgrading from 19mm to 25mm can cost $15,000 – $30,000+ for the city-side work alone. Always confirm servicing requirements before committing.
2. Tree Protection & Arborist Reports
If your build zone is within the drip line of a protected tree, you'll need an arborist report ($500–$1,500) and tree protection fencing during construction.
3. Grading & Drainage
Proper grading can add $5,000–$15,000 on sloped lots or properties with existing drainage issues.
4. Utility Connection Fees
Budget $3,000–$8,000 for Enbridge gas and local hydro provider connection fees.
5. Survey & Engineering Reports
Property survey ($2,000–$3,500), geotechnical report ($2,000–$4,000), and possibly a grading plan from a P.Eng.
How to Save Money
Choose slab-on-grade over a basement. Saves $40,000+ and simplifies the entire build.
Use pre-approved plans. Toronto and Mississauga offer free designs. Even elsewhere, proven plans save $5,000–$10,000 in architectural fees.
Build during the shoulder season. Late fall or early winter often means better contractor availability.
Right-size the unit. A 500 sq ft one-bedroom rents at only a slightly lower rate than 700 sq ft but costs much less to build.
Is It Worth It? The ROI Math
Build cost: $220,000 · Monthly rent: $2,200
Annual net income: ~$22,400 · Simple payback: ~9.8 years
Property value increase: $120,000 – $180,000
A well-built garden suite typically adds $120,000 – $180,000 to your property's appraised value. Combined with ongoing rental income, the total return makes garden suites one of the best real estate investments available to GTA homeowners.
Frequently Asked Questions
Can I finance a garden suite?
Yes. Most homeowners finance through a HELOC, construction mortgage, or refinancing.
Do I need to pay Development Charges?
Under Ontario's Bill 23, development charges for garden suites are waived or significantly reduced in most municipalities.
How long does it take to build?
From permit submission to move-in, expect 8–14 months total. Construction itself runs 4–6 months for a standard slab-on-grade build.
Do I need to pay HST?
New construction is subject to 13% HST. However, you may qualify for the HST New Residential Rental Property Rebate if used as a long-term rental.
Will my property tax go up after building a garden suite?
Yes, in most cases. Adding a garden suite increases the assessed value of your property, which typically results in a property tax increase. The exact amount varies by municipality and depends on the size and value of the suite. However, in the GTA, homeowners generally don't see a significant increase in property taxes after building their backyard suites. Even if there is an increase, this is easily offset by the rental income the suite generates — even at the higher end, property tax adds less than $300/month to your costs against $2,000+/month in rental revenue. Contact your local MPAC (Municipal Property Assessment Corporation) office for a more specific estimate based on your property.