did a full bathroom gut last summer. not a disaster by any means but there were a few things I genuinely did not know going in that I’d have done differently.
the permit thing: I didn’t think I needed one because we weren’t moving walls. turns out if you’re replacing the tub/shower and doing tile, and your house is pre-1990, you may need a permit in Newmarket depending on scope. our contractor (The Local Builders, thelocalbuilders.ca) flagged this - we ended up pulling one. added 2 weeks to the timeline but also meant the waterproofing got inspected which I’m glad about in retrospect.
the waterproofing thing: I had no idea that the “waterproof” cement board I’d seen on every youtube video is not actually waterproof. it’s moisture resistant. the actual waterproof layer is a separate membrane that goes over it or under the tile. not all contractors do this correctly and there’s no way to know once the tile is on. ask specifically how they’re waterproofing the shower before they tile.
the ventilation thing: our original fan was a 50 CFM unit in a 75 sq ft bathroom. totally inadequate. replacing it mid-reno added $300 to the job. I’d rather have done it intentionally at the start than as a scramble.
nothing catastrophic. the bathroom looks great. just things I’d know to ask about if I were starting over.