Subfloor in bathroom?

[JustBeingJuliet]

I'm in the middle of redoing my bathroom and currently have just the old, slightly knackered looking wood floor, as the tiles have been ripped up. Looking at fitting vinyl in there, so I know I need a subfloor laying first. What material do I use for this? Is it just a sheet of 18mm plywood?

vinyl does not need anything special.

Ceramic tiles need a very rigid subfloor, otherwise they crack.

Do you mean you are looking at the joists, or are there floorboards or chipboard?

It's floorboards and it's not level at all so needs something over it. This is how it looks at the minute!

it looks like the boards have been cut and lifted by past plumbers. The floor under the bath is likely to be especially bad.

You could consider taking up all the old boards and putting down a new floor in 18mm WBP ply. If you just want to make the surface fairly flat and smooth, 6mm ply will be enough for a vinyl floor.

In a bathroom, it is useful to cut the ply into pieces that can be lifted to get at the plumbing beneath.

The floor under the bath is shocking! I'm going to do a single piece up to the bath, then seperate pieces under the bath I think. So 6mm is enough? That's helpful :)