Floor creaks after laying aquapanel

[Oggy66]

Well having searched around for the best preparation for tiling a bathroom floor over electric UFH I did the following:

• - screwed down the existing chipboard floor to the joists
  - bedded the heavy resin shower tray on mortar
  - glued & screwed aquapanel round the tray to the rest of the floor (using BAL single part flex & aquapanel screws)
  - taped the joints
  - filled the gaps round the edges and covered the tape with more BAL spf

Great, I thought, all ready for the UFH and tiles ……..but now it's started creaking in a couple of areas near the tray where it didn't used to creak before

What's gone wrong? And what's my best course of action to fix it before laying the UFH & tiles?

 

[gcol]

So you applied cement to chipboard to bed the shower tray?

 

[Oggy66]

Yes - is that a problem?

The manufacturers instructions (if I remember correctly!) said to ensure the floor was securely fixed, seal it and then lay the tray on a minimum of 6mm weak mortar - so I screwed it down, sealed it with the dreaded PVA and then layed the tray on mortar.

 

[gcol]

The last thing you apply to chipboard is anything with moisture in it. It swells just like weetabix. The pva won't waterproof it - it'll just slow the passage of water through to the chipboard.
You're probably looking at a swelled chipboard floor that's loosened around the screws (because it's got wet) and now it's dried out, is rubbing when you apply weight to it.