What are common hidden bathroom renovation costs?

The common hidden costs are rotten joists, dead pipework, tanking and backer boards, waste disposal, and making good the rooms next to the bathroom. Most of them share one thing: they only show up at strip-out. Until the tiles are off and the bath is out, nobody can see the state of what sits underneath.

Rotten joists top the list. A bath that has leaked slowly for years softens the timber below it, and the floor feels solid right up until it is exposed. Dead pipework is next: old lead runs, corroded fittings, plumbing that was capped off and abandoned by a previous owner. In the ex-rental flats we take on around Lewisham and Balham we almost expect it. Then there is what the walls need before tiling can start. Backer boards and tanking to the wet areas are not optional, but plenty of quotes quietly leave them out and charge for them later.

Two more that surprise people. Disposal, because a stripped bathroom fills a skip faster than you would think, and a skip permit on a London street is not cheap. And making good around the bathroom: the hallway ceiling below, the wall where a chase was cut, the landing carpet that took a beating.

Our approach is to survey properly first and put these items in the written quote where we can see them coming. The quote is fixed, so the price we quote is the price you pay.