Bouncy-as-hell bathroom floor.

[wanabechippie]

Hey.

The Mother-in-law (again) is after a new bathroom suite complete with tiled floor. The bathroom is on the first floor. I'm not sure if its because the joists are too weedy but everytime anyone walks across the floor it rolls and creaks like your on a sodding boat! I swear the shift is something like 15mm in places!

I know there have been similar posts like this here about loft floor strengthening, but I couldn't find owt specifically about other habitable rooms, so sorry for any repeat!

How do i go about strengthening the bathroom floor? I'm thinking it would need to be a case of: strip out the entire bathroom suite, take up the floor boards, replace/sister larger joists to old ones (joist hangers on the outer walls??) and fix 12mm-18mm WBP ply to the joists (without replacing the old boards?) then tile over the top as per the wood floor sticky.

That about right? If so, what size/type of joists would I need to use and would 18mm WBP be overkill?

Thanks muchly.

 

[JohnD]

I'd be inclined to take parts up the old floor and see what the cause is first.

Might be rot, might be excessive notching. Might possibly be inadequate boarding but this is less likely than chipboard that's turned to cornflakes due to damp.

 

[gcol]

If you're taking the floor up and replacing with ply, 18mm is a minimum. 25mm would be better.

 

[wanabechippie]

Righty-ho then. Cheers.

If the joists are a tad on the wimpy side, would screwing 25mm ply directly to them do anything to stop the bounce or would I still need to strengthen the joists?

 

[PilotPete]

This is what I did to my ensuite bathroom floor to strengthen it enough to take a tiled floor. Ensure the existing joists are securly supported at each end and then just use 4x2 to brace where required.



I then covered the floor with 18mm WBP ply, screwed down at 300mm centres.



On top of this I put 6mm Marmox boards for insulation, then undertile heating cable and a self levelling compound to bury the cable.