What are common bathroom renovation mistakes?

The most common bathroom renovation mistakes are layout mistakes, and the biggest is cramming too much in. A bath, a separate shower and twin basins will not fit comfortably in a two by two metre room in an Edwardian semi, whatever the 3D render suggests. You end up with a door clipping the basin, no clearance in front of the toilet and a room that is awkward to use and worse to clean. Pick the two things you actually use and give them space.

Extraction is the next failure. People fit a powerful shower and keep the small fan that was already there, then wonder why the ceiling is speckled with mould by winter. Extraction has to match the steam you are producing, and it has to duct to the outside. Lighting and sockets go wrong quietly: one centre pendant puts your face in shadow at the mirror, the one place you need light, and a shaver socket hidden behind the door helps nobody.

Then there is sequence. Bathrooms only work when built in the right order: strip out, first fix plumbing and electrics, boarding, tanking, tiling, then second fix and sealant. We have been called into jobs in Bromley and Beckenham where the tiling went up before the pipework moved, and the owner paid for the same wall twice. Which products to buy is a separate question. Get the layout and the order of works right and the room will do its job for twenty years.