Over boarding chipboard flooring with 6mm Marmox Board

[richardbell81]

Hello all,

Following on from my last thread... tiling-on-to-chipboard-flooring-t53200.html

I wondered how you would suggest fixing 6mm Marmox board to 18mm chipboard flooring. I haven't been able to do anything about it since my last post as i've been away so just to re-cap...

I'm tiling a small bathroom floor (2.2 m2, pic attached) with large porcelain tiles (600x300x10mm). I removed the old damaged floorboards and replaced them with 18mm Tongue & Groove Waterproof Treated Chipboard Flooring 18mm. I would say the floor is solid with 'slight vibration'. I wanted to avoid adding any more height to the floor so I was planning to tile directly onto the chipboard with BAL spff... but thanks to all of yours advice I have decided to compromise and overboard with a 6mm tile backing board. I can't go any thicker than this which is why it's a compromise! I have decided to use Marmox/Wedi board as it will add that bit more strength to the floor, it's waterproof and is a much better substrate to tile on to. I realise I should go for a thicker backer board but I really can't add any more height to the floor due to the position of the soil pipe!

My plan was to...
- screw the Marmox board down (screws 150mm apart) with a 'sandwich' layer of adhesive in between. Was going to us either BAL spff (or Supercover rapid flex as I have a spare bag!).
- Tile onto the Marmox board using BAL Single Part Fastlex
- Grout Using BAL Wide Joint + GT1 additive

How does that sound? Your advice really is appreciated!