Floor prep

[Woody123]

Hi all

Doing a job for the father in law at the weekend and he insisted on doing the prep to hellp me out! Anyway the original floor is 18mm weyrock floor i think and he has overboarded it with another 18mm tongue and groove chipboard. I have checked the floor is screwed down properley and there is no movement in the slightest. I have never used this stuff before as i have always overboarded with ply. Does anyone else ever go down this route as i asked how much he paid for it and it was only £5.69 for a sheet of 2.4m x 0.6m from B & Q so it was alot cheaper than ply. Im happy there is no movement so will this be ok to tile to? As it is not the norm for me am i just being paranoid? (By the way im just laying ceramics and will be using a flexi addy and grout)

 

[murf]

I would never tile onto chipboard, it can break down over time
no matter what adhesive you use.

 

[brian c]

not the best substrate to tile to....should have used ply.

 

[grumpygrouter]

Solidity is the main issue with floors IMO. Some guys on here will not tile directly to chipboard no matter what as it can be a bit unstable. Ideally, 18mm ply would have been better but as you say, it is more expensive. You can use an appropriate adhesive such as Ardexflex 7001 or maybe Mapei Keraquick with latexplus but really, you would be better overlaying with 6mm hardiebacker first. Tjhs get around some of the instability issues of chipboard.

 

[Woody123]

I thought there must be a reason why i have never seen this method used. Is it just if moisture gets in it breaks down easy? I know he wont change it now as he has fitted his new bath and shower tray on top of it. Would SPF not be suitable for this job then grumpy? you have me worried now :mad2:

 

[cornish_crofter]

As someone who has repaired several chipboard bathroom floors, I would advise against chipboard as a flooring material in the bathroom in general, even the treated stuff.

Tiling it would IMO make the problem 10 times worse. If it were untiled the water in contact would have half a chance to evaporate or disperse. Tiling it just confirms its demise.

I did use a couple of pieces to stick a bath onto recently to deal with floorbaords in poor condition but that is under the bath and tucked out of the way of the accessable floor area. I would have prefered to use ply but this stuff was to hand.

I think you're going to have to sit your FiL down and have a chat with him over this. The chipboard needs to come up, and be replaced with ply. The stuff under his bath can stay.

 

[grumpygrouter]

Because chipbaord is made up of, well, chips....the board can breakdown and debond in a worst case scenario, as in when it gets wet because it can "blow". Ardex for instance say their adhesive is suitable and indeed, I have used it straight onto chipboard, albeit not in a bathroom. SPF (I am asuming you are talking BAL here) really isn't suitable. bal would recommend fastflex for chipboard. if it was me and I HAD to tile onto it, then I would opt for the Ardex or mapei Keraquick/latex plus solution. backerboard would be better though.

 

[Woody123]

Oh dear oh dear, he is not going to like it but i will have to advise him of the pitfalls as it is on my head if it fails really.
Im not looking forward to this!

Cheers for the input people as i wasn't aware of the properties of the chipboard flooring.

 

[Woody123]

Cheers grumpy. It could yet come to me having to tile onto it so your advice is greatly appreciated.

 

[doug boardley]

I fall into the category of "won't tile onto chipboard" seen addys over the years that say it's now possible to tile onto c/board; none that I know have fulilled that promise!

 

[Woody123]

Just abit more info needed from you good people. I have been there today and all his fittings are in. shower tray, bath, all units for sink and concealead toilet . There isn't actually much floor space to tile. Could i possibly tank the area and seal all of the grout lines thus minimising the risk of moisture getting to the boards and then use a suitable adhesive for chipboard i.e keraflex with latex? I know ideally it needs to come up but he doesn't want to do this. I have suggested putting backerboard down but this will raise it even further than what it is already with the 18mm already on top of the original floor. If i was to go down the backer board route would that elimanate the risk of debonding?

 

[cornish_crofter]

I'm not an expert here but you may be able to use a tanking membrane, or screw down some 6mm hardibacker onto the chipboard.

The latter approach would increase your floor height by 6mm. The former approach may work, provided that it was tanked and sealed sufficiently to stop water getting into places like the outside of the WC bowl.

 

[grumpygrouter]

I'm not an expert here but you may be able to use a tanking membrane, or screw down some 6mm hardibacker onto the chipboard.

The latter approach would increase your floor height by 6mm. The former approach may work, provided that it was tanked and sealed sufficiently to stop water getting into places like the outside of the WC bowl.

looks like Hardie is out Hugo. I personally see little point in tanking as my feeling as I have got more experienced with chipboard is that you need to have something screwed through it to stop potential tile delamination. If you are going to stick a tanking membrane to the chipboard then stick tiles to the membrane, you still have the potential to have the chipboard breakdown, if you see what I mean. in this case you may as well just glue straight to the chipboard with good adhesive.

My preferred way now is to glue and screw Hardiebacker first as you then have a mechanical fixing aiding keeping things down....do you follow what I mean, I know what I am trying to say, but it doesn't seem to be coming out right!

 

[White Room]

Had to finish off some tiling a plumber had done, he used treated chipboard for the boxing and applied bal white star, tiles fell off the addy never stuck whatsoever to the chipboard

 

[Woody123]

Yeah grumpy i know what you mean and im thinking that could well be the way forward. I have warned him of all the pitfalls and he accepts that in hindsight he should of used ply (which being more expensive at first could well turn out to be cheaper in the long run if the floor has to come up.) but still doesn't want to change it and said he knows it wont be my fault if anything happens.
Thanks again for the First class advice everyone.