How much does it cost to add a new bathroom where one didn't exist before in a Toronto home?

Adding a completely new bathroom to a Toronto home typically costs $20,000 to $50,000 or more, depending on whether you're building a powder room, a three-piece, or a full four-piece bathroom, and how far the new location is from existing plumbing stacks. This is one of the most complex and expensive bathroom projects, but it also delivers one of the highest returns on investment for GTA homes — adding a bathroom can increase property value by $20,000–$40,000 in the Toronto market.

The cost breaks down into several major categories, with plumbing rough-in being the biggest variable.

Plumbing Rough-In — $3,000–$10,000

This is the foundation of any new bathroom addition and the largest variable cost. If you're adding a bathroom directly above or below an existing one, the plumbing connections are relatively straightforward — you're tapping into an existing drain stack and supply lines. Rough-in plumbing for a new bathroom near existing stacks runs $3,000–$5,000 in the GTA.

If the new bathroom is far from existing plumbing — on the opposite side of the house, in a converted closet or bedroom, or in a basement without a rough-in — costs escalate to $5,000–$10,000 or more. The plumber needs to run new drain lines with proper slope (1/4 inch per foot for 3-inch and 4-inch drains), connect to the main stack, install proper venting, and run new hot and cold supply lines. In a basement bathroom where the drain is below the main sewer line, you may need an ejector pump or macerating toilet system, adding $1,500–$3,000.

A building permit is required from the City of Toronto for all new bathroom plumbing. Your licensed plumber handles the permit application and arranges the required inspections.

Electrical — $2,000–$4,000

Every new bathroom needs at minimum one GFCI-protected circuit for the receptacle outlet, a dedicated circuit for the exhaust fan, and a lighting circuit. If you're adding heated floors, that's another dedicated GFCI-protected circuit. An electrical permit is required, and all work must be inspected by the ESA before walls are closed. GTA electrician rates run $75–$120 per hour, and a complete new bathroom electrical rough-in plus finish is typically $2,000–$4,000.

Framing and Structural — $2,000–$6,000

If you're converting an existing room or closet, framing costs are modest — building partition walls, framing the door opening, and creating plumbing walls (2x6 walls for drain pipes, especially if you're installing a wall-hung toilet with a concealed carrier). If the addition requires structural modifications — removing a load-bearing wall section, reinforcing floor joists to support a heavy soaker tub (a full bathtub weighs 500–800 pounds with water), or modifying the home's layout — structural engineering assessment and additional framing costs can add $2,000–$6,000.

In older Toronto homes (pre-1945), floor joists may need sistering or reinforcement to meet current Ontario Building Code standards for the additional weight and plumbing penetrations. This is common in homes across established neighbourhoods like the Annex, Roncesvalles, Riverdale, and the Danforth.

Finishing — $10,000–$25,000

Once the rough-in trades are complete, finishing costs align with standard bathroom renovation pricing. A basic three-piece bathroom (toilet, vanity with sink, shower) with stock materials runs $10,000–$15,000 for finishes. A mid-range four-piece bathroom (adding a tub) with porcelain tile, semi-custom vanity, and quality fixtures runs $15,000–$25,000. Waterproofing, tile, vanity installation, toilet setting, fixture trim-out, drywall, paint, mirror, and accessories are all included in this phase.

By Bathroom Type

New powder room (half bath): $12,000–$20,000 total. The smallest and least expensive addition — only a toilet and vanity, no shower or tub plumbing. Ideal for converting a main-floor closet or under-stair space in a Toronto home.

New three-piece bathroom: $20,000–$35,000 total. Toilet, vanity, and shower. The most common addition for families needing an extra bathroom.

New four-piece bathroom: $25,000–$45,000 total. Toilet, vanity, shower, and tub. Full-featured bathroom, often added as a second-floor ensuite or basement bathroom.

Basement bathroom (from existing rough-in): $10,000–$25,000 total. Many Toronto homes built after the 1980s have basement bathroom rough-ins — capped drain and supply lines ready for connection. This significantly reduces plumbing costs and makes a basement bathroom addition more affordable.

Always verify that your contractor carries WSIB coverage and liability insurance, and ensure all permits are obtained before work begins. Need help finding a qualified contractor for a bathroom addition? Toronto Bath Remodeling can match you with experienced professionals through the Toronto Construction Network.