An overlay holds only where every old tile is still bonded, and in a shower it keeps whatever membrane lies underneath, leaks included. Six checks for floors, walls and showers, and where the 12 to 16 mm a floor gains runs into doors and drains.

One maker's warranty leaves heat cracks in its quartz with the owner and covers thermal-shock cracks in its sintered stone. That clause, your hob's manual and the state of the old tiles decide which material goes where.

A hollow tile, a straight crack and a lifted joint are three separate floor failures in Dubai apartments, with three different causes and three different bill payers. How to tell them apart with a coin, and what each one needs.