Over boarding Chipboard floor with 6mm Marmox board

[richardbell81]

Hello all,

Following on from my last thread 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!

 

[nybor62]

have you got the screws washers and jointing tape, and as you removed the old floor i would have gone with 18mm wbp ply instead of the chip board, imo

 

[richardbell81]

have you got the screws washers and jointing tape, and as you removed the old floor i would have gone with 18mm wbp ply instead of the chip board, imo

Using 25m galvanised screws with 30mm washers. Part of the reason for over boarding is that I know chipboard isn't the best substrate but I can't take up now as it has been screwed down (and glued in places where it covers the old upstairs concrete fireplace hearth).

 

[nybor62]

ok you seem to have it all covered

 

[richardbell81]

Using 25m galvanised screws with 30mm washers. Part of the reason for over boarding is that I know chipboard isn't the best substrate but I can't take up now as it has been screwed down (and glued in places where it covers the old upstairs concrete fireplace hearth).

Really? That's the first time i've heard that! :smilewinkgrin:

 

[Perry]

only thing you may get away with IMO is 10mm never gone any thiner stuck down with something like fastflex or timberflex then spf with the tiles

 

[richardbell81]

Really? That's the first time i've heard that! :smilewinkgrin:

So confusing, I suppose it comes down to personal experience. In my last post I had quite a few suggesting 6mm tile backing board. Would using Hardiebacker make a big difference as opposed to Marmox?

 

[macten]

If I was only going to overboard at 6mm I would use NoMorePly stuck down with their megastrength glue and screws.
Minimal height increase as not using a layer of adhesive and this stuff really works well for what you are doing.

 

[richardbell81]

If I was only going to overboard at 6mm I would use NoMorePly stuck down with their megastrength glue and screws.
Minimal height increase as not using a layer of adhesive and this stuff really works well for what you are doing.

Thanks for the advice! What Adhesive and grout for tiling would you recommend with NMP? Would the BAL spff and wide joint + gt1 still be my best bet? I do have a spare bag of Super cover rapid flex which I bought before christmas but was warned this wouldn't be flexible enough?

 

[Andy Allen]

bal single part fast flex, bal wide joint grout with gt1 admix is about the most flexable combination ive come across..

 

[prceramics]

ditra mat ?

 

[richardbell81]

ditra mat ?

I have considered Durabase but I just thought that over boarding would add more strength and help any minor deflection in the floor. Although a thin un-coupling membrane is very tempting if it would do the job!

 

[Perry]

So confusing, I suppose it comes down to personal experience. In my last post I had quite a few suggesting 6mm tile backing board. Would using Hardiebacker make a big difference as opposed to Marmox?

yes it wouldn't be as good as marmox IMO must of laid close to a million mts of floor tiles I have a little experience lol

 

[richardbell81]

yes it wouldn't be as good as marmox IMO must of laid close to a million mts of floor tiles I have a little experience lol

Thats a hell of a lot of floor tiles! So your saying use Marmox/wedi? Or have i read that wrong?

 

[Perry]

Thats a hell of a lot of floor tiles! So your saying use Marmox/wedi? Or have i read that wrong?

No if your floor is solid no movement cement board is fine you said you was going to put 6 mm marmox down spf no good on chipboard IMO was trying to help the best way to do a bad job as such marmox is a little more sound with adhesive IMO than cement board