Every spring, bathroom renovations in the GTA start with the same assumptions: cosmetic work doesn’t need a permit, tile is waterproofing, and the city takes two weeks to review. The first two are wrong.
What triggers a permit in a bathroom
Ontario Building Code draws the line at relocation, not replacement.
A new toilet in the same rough-in, a new vanity, a new shower door — none of that requires a permit. Move the toilet drain six inches to square the layout and you need one. That surprises homeowners more than almost anything else on a bathroom job.
Electrical beyond like-for-like replacement triggers an ESA permit. It’s separate from the municipal building permit, and the contractor pulls it, not the homeowner. New circuit for in-floor heat, a new exhaust fan, a heated towel bar on its own circuit — all need ESA sign-off before rough-in closes.
Structural work — wall removal or any expansion touching a load-bearing element — requires sealed drawings and a building permit. Wet room conversions (curbless showers, full wet rooms) often add a waterproofing inspection to the standard rough-in and final.
Toronto’s 15-business-day review clock only starts when the city considers the application complete. Drawings that don’t match, missing BCIN stamps, zoning notes that don’t reconcile — any of those restarts it. Build that buffer in before demo starts.
Tile is not waterproofing
OBC requires wet area waterproofing to meet CSA A118.10. That means a compliant membrane — Schluter Kerdi, Wedi board, RedGard, or equivalent — applied and cured before any tile goes down. The tile and grout sit on top of the membrane. They do not replace it.
Most of the water damage we see behind bathroom tile comes from one of two places: no membrane at all, or a membrane applied sloppily at the transitions. The floor-to-wall corner is where it fails. The membrane needs to run continuously from the floor up to at least 25 cm above the finished floor in the wet zone, with fabric tape bedded into the membrane at every corner — brushing over it is not enough.
If you’re getting quotes and the contractor doesn’t name the waterproofing system, ask. Which product, and how do you handle the floor-wall transition? That answer tells you more than the price does.
Ventilation: the thing that fails inspections
OBC requires a mechanical exhaust fan in any bathroom without operable windows. Even with windows, if the reno touches electrical, the inspector will check ventilation.
Two things get failed consistently: a fan ducted to the attic instead of an exterior wall cap, and a fan rated under 50 CFM in a full bathroom. Target roughly 1 CFM per square foot of floor area. Soffit vents don’t count. Terminate the duct outside.
Trade sequencing for a gut reno
Demo → rough plumbing → rough electrical → ESA rough-in inspection → cement board substrate → waterproofing membrane with fabric tape at transitions → tile setting → grout → fixtures → ESA final → building final.
The break that causes callbacks: plumbers setting the toilet before grout is done so they can walk through freely. Don’t allow it. Grout lines cracked by foot traffic around the toilet flange are a warranty call that’s entirely avoidable.
Rough-in and final inspections in Toronto book out 5–10 business days. Get the request in before the work is ready, not after.
If you’ve run into any of this on an Ontario bathroom reno — a permit surprise, a waterproofing dispute, an inspection backlog — share it here. The specifics are what make threads like this useful.
For the same breakdown on kitchen renovations — permit triggers, trade order, and where GTA timelines stall — see the kitchen reno guide for Ontario (2026).
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