| Scope | Typical range | Notes |
|---|---|---|
| 2-piece powder room (rough-in exists) | $10–14K | Toilet, vanity, tile floor |
| 3-piece with tiled shower | $18–28K | The standard basement build |
| Breaking concrete for new drains | +$3–6K | When no rough-in exists |
| Sewage ejector (below sewer line) | +$2–4K | Pump and pit when gravity cannot drain |
| Spa-grade upgrade (stone, glass, niche) | +$8–15K | Matches our bathroom portfolio |
A basement bathroom lives in the most moisture-exposed room of the house. We build them waterproof-first: membrane systems behind every tiled surface, moisture-resistant board instead of standard drywall, and mechanical ventilation sized for a below-grade room. It is the difference between a bathroom that looks good on handover day and one that still looks good in year ten, which is why every Desire Basements bathroom carries the same lifetime warranty as the rest of the build.
New plumbing and electrical below grade require permits and staged inspections in every GTA municipality. The plumbing rough-in is inspected before the slab is closed, and electrical work is ESA-inspected. If a contractor suggests skipping permits on a basement bathroom, that quote is cheaper for a reason. Our free quote checklist shows what else should be itemized before you sign anything.
The median completed basement renovation in our 2026 Cost Report is $103,000, and nearly every project at that level includes a bathroom. In a legal basement apartment it is required in practice, and it is a large part of why GTA suites rent for $1,700–$2,400 per month. To price your whole project, try the basement cost calculator, and monthly-payment financing is available on every build.
Every basement bathroom starts with one question: is there a rough-in? A rough-in is a set of capped drain and vent stubs the builder left under the slab, usually near the main stack. If it exists, the toilet, shower and vanity drains are already waiting below the concrete and the plumber connects to them. If it does not, we cut the slab, trench to the main drain, run new lines, backfill and pour. That is the +$3,000 to $6,000 line in the table above, and it is the single biggest reason two bathrooms of the same size can come in thousands apart.
The second question is where your house's sewer line sits. Most GTA homes drain by gravity: the basement fixtures sit above the municipal line, water runs downhill, done. Some do not. Older Toronto and Etobicoke houses on low lots, and any house where the basement has been underpinned, can end up with fixtures below the sewer. There the fix is a sewage ejector: a sealed pit under the slab with a pump that lifts waste up to the main line. It is reliable, quiet when installed properly, and it adds $2,000 to $4,000. We tell clients which house they have before anyone picks a tile.
Venting is the part nobody sees and the inspector always checks. Every fixture needs a vent so water flows and traps hold their seal. Below grade, that vent has to tie into the existing stack or run up through the house, and the route is often the hardest plumbing puzzle in the basement. The bathroom fan is separate: a below-grade room needs mechanical exhaust ducted outside, not into a joist bay, sized for the room and on a timer so it actually runs.
All of it is permitted and inspected. The plumbing rough-in is inspected in the open trench before the slab is closed. Framing and insulation are inspected before drywall. Electrical is ESA-inspected. Then the finishing starts, and in the shower that means a Schluter-KERDI system: a bonded waterproofing membrane over the whole shower assembly, walls and floor, so the tile is a finish and not the thing keeping water out of your framing. A curbless shower, where the floor slopes to a linear drain with no step, uses the same system on a recessed pan. A steam shower adds a vapour-tight enclosure to the ceiling, a sloped ceiling so condensation runs to the wall instead of dripping, and a steam generator in an adjacent closet. Ben Sinclair Avenue and Rattlesnake Path both have one; Austin Rumble Court has a steam shower in the ensuite and a dry sauna with its own steam unit next door.
Once the plumbing is settled, the price is decided by surfaces and glass. Tile to the ceiling is the choice our clients ask about most. It costs more in tile and labour than stopping at the shower head, and it is worth it in any bathroom with a steam shower, or any room you want to photograph. The bathroom on Botfield Avenue in Etobicoke took it one step further with a tiled ceiling, which turns a small room into a single continuous surface.
Inside the shower, the details add up. A recessed niche is framed, waterproofed and tiled as its own small box, and a niche with a mitred edge costs more than one with a metal trim. A built-in bench, like the one in the Rattlesnake Path steam shower, means more framing, more membrane and more sloped tile. Glass is the next line: a fixed panel is the least, a frameless swing door with a 10 mm panel is the most, and a curbless shower usually wants floor-to-ceiling glass because there is no curb to stop water at the threshold.
A heated floor is the upgrade with the best return in daily comfort. An electric mat under the tile, on a programmable thermostat, takes the one honest complaint about a tiled basement bathroom, the cold floor, off the table. Baynards Lane and Rattlesnake Path both have it. The vanity is the last variable and one of the widest: a stock vanity with a moulded top is a few hundred dollars, a custom floating vanity with a stone top, an undermount sink and wall-mounted faucets is several thousand, and the mirror above it ranges just as widely. None of these decisions are wrong. They are the difference between the bottom and the top of the range, and a 3D design shows you which ones you are actually paying for before the tile is ordered.
Three layouts cover nearly every basement. A two-piece powder room is a toilet and a vanity in about 20 square feet, usually tucked under the stairs or off the bar. Where the rough-in exists it lands at $10,000 to $14,000, and it is the right answer for a basement whose main job is entertaining. A three-piece adds a tiled shower and is the standard basement bathroom: $18,000 to $28,000 as part of a full renovation, with the low end a straightforward shower over an existing rough-in and the top end a curbless, glassed, tile-to-ceiling room with a heated floor. A bedroom downstairs almost always means a three-piece: Botfield Avenue in Etobicoke and Carlyle Crescent in Aurora both put a bedroom and a bathroom side by side.
The spa ensuite is the third layout, and it is where the $8,000 to $15,000 spa-grade upgrade in the table goes. It is a three-piece plus: a steam shower with a bench, a heated floor, tile to the ceiling, and often a sauna beside it. Rattlesnake Path in Oakville pairs a tiled steam shower with a bench against a 19-foot bar and a 100-inch fireplace in the room outside. Ben Sinclair Avenue in East Gwillimbury puts a custom dry sauna with a steam unit next to a tiled steam shower. Baynards Lane in Richmond Hill has a curbless shower and a dog-wash spa on the same heated floor. Each was built as part of a full basement in the $170,000 to $270,000 range.
If you are deciding between the three, the honest guidance is this. Build a powder room if nobody will sleep downstairs. Build a three-piece if there is a bedroom, a gym or a guest suite for family. Build the spa ensuite if you want the basement to be the reason you stay home. Our bathroom portfolio shows all three finished, and the project gallery shows the basements they sit in.
Yes. New plumbing and electrical below grade require permits and inspections in every GTA municipality, with the rough-in inspected before the floor is closed.
Yes. The concrete floor is cut to run new drains, or a sewage ejector handles fixtures that sit below the sewer line. Both are routine parts of a full renovation.
For legal suites it is effectively required, and in family basements it is consistently the most-used upgrade we build. It also supports resale value more than any other single basement feature.
Only if the fixtures sit below your home's sewer line. Most GTA basements drain by gravity. Low lots, older Toronto and Etobicoke houses and underpinned basements sometimes need an ejector: a sealed pit and pump under the slab that adds $2,000 to $4,000. We confirm which case applies before the layout is drawn.
They sit in the spa-grade upgrade band, $8,000 to $15,000 on top of a three-piece, depending on glass, tile to the ceiling, a bench and a heated floor. A curbless shower needs a recessed Schluter-KERDI pan and a linear drain; a steam shower adds a vapour-tight enclosure, a sloped ceiling and a generator. Rattlesnake Path and Ben Sinclair Avenue both have tiled steam showers.
A two-piece is a toilet and vanity, $10,000 to $14,000 over an existing rough-in. A three-piece adds a tiled shower and is the standard basement bathroom at $18,000 to $28,000. A spa ensuite is a three-piece with a steam shower, heated floor, tile to the ceiling and often a sauna beside it, as on Rattlesnake Path, Ben Sinclair Avenue and Baynards Lane.
