When renovating a bathroom, what comes first?

The survey comes first, before you choose a single tile. We check where the soil stack runs, which way the floor joists go, the water pressure, the state of the electrics and whether there is any extraction at all. In the Victorian terraces and Edwardian semis we work on, those five things decide what the room can sensibly become. Skipping this stage is how people end up with a shower that dribbles or a toilet that can't go where they wanted it.

Next, lock the layout and the ventilation before any work starts. Moving the toilet is the expensive decision because the soil pipe has to follow it, so settle that early. Decide where the extractor fan sits and where it vents (outside, never into the loft). Then order everything: sanitaryware, brassware, tiles, the lot. A job that starts before the materials arrive is a job that stalls.

The works themselves follow a fixed order. Rip-out, then first fix plumbing and electrics, then boarding and waterproofing (we tank the wet areas), then tiling, then second fix where the bath, basin, toilet and fan actually go in, then decoration and sealant last. Each stage buries the one before it. Once the tiles are on, the pipework behind them is set for good, which is why changes of mind after first fix cost real money. Make the decisions before the rip-out, not during it, and the job runs straight through.