The project in brief
A 453 sq ft detached ARU, permitted by the City of Kingston and built from bare yard to finished building in about three months for about $210,000, including the fence, sod, deck and shed. The corner lot let the unit face the side street with its own driveway and entrance, so clients do not need to pass the main house or its back yard.
The unit was planned as a separate, quiet space for a massage therapy practice: a treatment room, a bathroom and a second room that can change use over time. Because it is permitted as a detached ARU, the building can serve other uses later, such as a rental or a family suite, subject to the City's rules for that use.
The layout and permit drawings were designed by House of Three Design. We built it.
Why a corner lot works well for a garden suite
On an interior lot, a back yard unit usually shares the main driveway and is reached down a side yard. A corner lot has a second street frontage, which can give the new unit:
- Its own access: a separate driveway and front door for clients, tenants or family.
- More privacy for both buildings: the main house keeps its back yard, and the unit faces its own street.
- Easier construction access: excavators, concrete trucks and lumber deliveries can come in from the side street instead of crossing the existing yard.
Corner lots also come with their own zoning checks, such as exterior side yard setbacks and sight lines at the intersection. We confirm those during the design and permit stage, before anything is built.
How the build went
- Site prep: removed a mature tree and cleared the build area.
- Foundation: excavation, poured footings, concrete foundation walls and a slab with plumbing rough-ins.
- Structure: wall framing, roof trusses, sheathing and house wrap.
- Envelope and services: spray foam insulation, electrical panel and rough-ins, then drywall and finishes.
- Exterior: dark grey siding, asphalt shingles, white windows and a gravel driveway.
- Yard: cedar privacy fence, deck, a shed, grading, new sod and stepping stones.
What it cost
The total project cost was about $210,000 in 2024. That covered the 453 sq ft unit plus the yard work around it: the cedar privacy fence, new sod, the deck and a shed.
Because the total includes the outdoor work, the unit itself cost less than the roughly $460 per square foot you get by dividing $210,000 by 453 sq ft.
Small detached units cost more per square foot than large ones because the expensive parts do not shrink with the floor plan: the foundation, the bathroom, water, sewer and electrical connections, permits and inspections. Your price will depend on your lot, how far services have to run and the finishes you choose. Our ARU calculator shows how rent or a City incentive changes the payback.
This unit was built before Kingston's current ARU incentives were available, so no City funding was used. A similar detached unit today may qualify for a forgivable loan of up to $40,000, though new applications are currently waitlisted. See the Kingston ARU incentive guide for the conditions.
Inside the unit
The treatment room has pot lights, a warm pendant fixture and wood-look flooring. The three-piece bathroom has a wood vanity, a white counter and a glass shower. The second room has large windows on two walls and is set up as a fitness space for now.
Planning something similar? Read about our garden suite builds, check the Kingston ARU rules, or try the lot checker.