Is my bathroom floor stable enough for tiling?

[vetinry]

Good evening
We're finally at the stage of installing the new master bathroom in our ongoing renovation project. After careful consideration, I've decided to go for electric UFH rather than wet becuase I didn't want to have to take up the bathroom floor.

However, the plumber has said that he thinks that the joist are too far apart and that I may have problems with tiles. The joists are at approx 600mm centres and there is 22mm plywood over the top. I'm keen not to raise the floor level too much because we will be carpeting the hallway and so ideally I don't want a big step up into the bathroom.

But, to make a better key for tiling, and to provide some downwards insulation for the UFH, I was planning on putting a thin tile backer board down.

I was really hoping not to have to lift the existing floor but question is, will this provide enough rigidity for tiles, or am I going to have to strengthen the floor?


Any advice gratefully received.

Steve

[Dave]

600 centres , are these TGI joists ?


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- Sent from my iPhone

[peteablard]

Hi Steve,
600mm centres are to far apart to eliminate all deflection from the floor. I would lift the ply and add extra supports between the joists at 300mm centres. A little bit of extra work now will save you a lot of problems in the future
Cheers

[vetinry]

Thanks for the replies.

Dave - Not sure what TGI joists are. They are 8 x 2 timber joists.
Pete - should I just use noggins at 90 degrees to the main joists? If so, what size wood should I go for? Will 4 x 2 be strong enough?

I guess it's the answer I was expecting but not hoping for. At least it will allow me to put some insulation in the void below the floor.

So, if I've strengthed the floor, do I still need to use tile backer board, or could I lay the UFH cable and tiles directly onto the ply?

Steve

[peteablard]

4x2 at 90 degrees will be fine mate. I'd still use 6mm insulation boards on the ply