The City of Kingston now allows additional residential units (ARUs) — including detached garden suites — on most residential lots. Done well, a garden suite is a real second home: rentable, comfortable to live in, and a meaningful addition to your property's value.
The constraints are usually three things: lot coverage and setbacks, parking, and the cost of running water, sewer and hydro to the new building. The first thing we do on any garden suite enquiry is a feasibility check on site to confirm all three.
Costs in 2026 are running $300,000 to $450,000 fully built for a small one-bedroom detached suite, depending on foundation type, how far the services have to run, and finish level. A two-bedroom or larger goes up from there.
Timelines: six to ten months from permit to finish. Permit approval through the City's ARU pathway is usually faster than a major addition because it's a streamlined process, but expect eight to sixteen weeks.
What we'd tell anyone considering one: budget for the services properly. Trenching for water and sewer is the line item that surprises people, and skimping there is what makes the difference between a garden suite that works and one that has problems for years.