Bathroom floor prep

[SomebodyElseDoIt]

I've now stripped a bathroom pretty much back to bare walls/floor. I now want to start putting it back together, starting with the floor...

The existing/remaining floor is T&G, about 22mm thick. It is in reasonable position [edit:condition!] i.e. no rot, and has only bashed about in a couple of places by plumbers and electricians. The joists centres are at 30/57/50/60cm spacing. I've got room for perhaps 15mm of additional material under the new tiles and adhesive.

So should I be adding ply, cement-based backer board, both, or something else? I've even had advice before that I should rip up the floorboards, sister the joists and add noggins, but I'd like to avoid that if not absolutely essential, not least because the bathroom (stud) walls are built on top of the floorboards.

The bathroom won't have a bath in it, just loo/sink/shower. It isn't going to be a wetroom.

 

[Happyplumber]

No more ply is perfect for this job,there is no need to rip out perfectly good tongue and grove floor boards

Make sure to use the adhesive and screws

 

[SomebodyElseDoIt]

Thanks, very helpful.

Now, as it happens, I do need a plumber as a) I don't know which of the many gate valves and stopcocks turns off the hot water [and I can't turn any of them!] b) I need the shower pipework moving c) I'll need a new radiator plumbing in... and probably a few other things...

 

[ree]

Ask the plumber to label the valves and isolators for you.

While the plumbers there, practice turning them on and off esp. any gate valves.

Work out best you can, before the plumber arrives, where everything is going to be centred. Will the WC be raised or moved etc.

 

[ree]

Ask the plumber to check for pipe squeak or hammer while the wall or floor's open - you dont want tile down, and then to start hearing the dreaded noises.