Can I add a second bathroom or convert a closet to a powder room in my Toronto condo?

Adding a second bathroom or converting a closet to a powder room in a Toronto condo is technically possible but involves significant plumbing, structural, and approval challenges that make it one of the most complex condo renovation projects you can undertake. The feasibility depends almost entirely on your unit's proximity to the existing plumbing stack and your condo board's willingness to approve the work.

The plumbing stack is the deciding factor. Every plumbing fixture needs to drain into a vertical waste stack, and in a condo, this stack is shared by every unit above and below you. A new powder room needs, at minimum, a toilet drain (3-inch pipe) and a sink drain (1.5-inch pipe), both of which must connect to the building's waste stack. The critical constraint is drain slope — the pipe from your new toilet to the stack needs a minimum slope of 1/4 inch per foot, and in a condo where your floor is another unit's ceiling, there is typically only 1-2 inches of space available between the finished floor surface and the concrete slab below. This limits how far you can practically run a toilet drain from the stack to roughly 6-8 feet without building up the floor significantly.

If your proposed powder room location is within that distance of the existing plumbing stack, the project is likely feasible from a plumbing perspective. If it is on the opposite side of the unit, 15-20 feet from the stack, the plumbing becomes either impractical or requires a macerating toilet system (like Saniflo) that grinds waste and pumps it to the stack through small-diameter pipe. Macerating systems cost $1,500-$3,000 for the unit and are noisier than gravity-drain toilets, but they solve the distance-from-stack problem when conventional plumbing is not feasible.

Approvals and Permits

This project requires multiple layers of approval in Toronto. First, your condo corporation must approve the renovation — adding a bathroom is a significant modification that most boards will scrutinize carefully. You will need architectural drawings from a designer or architect, a structural engineering report confirming the floor can support the additional fixture weight and that proposed modifications do not affect structural elements, and a plumbing engineering assessment confirming the building's waste stack can handle the additional fixture load. These reports alone cost $2,000-$5,000.

You will also need a building permit from the City of Toronto Building Division for the new plumbing connections. Plumbing permits require that the work be done by a licensed plumber and inspected before walls are closed. An electrical permit is required for the new bathroom's lighting, exhaust fan, and GFCI outlet, with ESA inspection.

Realistic Costs

A closet-to-powder-room conversion in a Toronto condo typically costs $15,000-$30,000 depending on the distance to the plumbing stack, the extent of floor and wall modifications, fixture selections, and finishing. This includes all engineering and permit costs, plumbing rough-in, electrical, ventilation (you must provide mechanical exhaust per Ontario Building Code), flooring, wall finishing, fixtures, and a pocket or barn door to maximize usable space in the small room.

The value proposition can be strong — in the competitive GTA condo resale market, adding a second bathroom to a one-bathroom unit can increase resale value by $20,000-$40,000 depending on the building and neighbourhood. For families or roommate situations, the functional value of a second bathroom is even higher. Consult with a contractor experienced in condo plumbing modifications early in the planning process to assess feasibility before investing in engineering reports and architectural drawings.