Options when tiling over chipboard.

[FreeD]

I've been reading through alot of the posts regarding tiling over chipboard. I have a job to quote for coming up tiling over green chipboard, currently its covered in lino this is fixed to the chipboard with some kind of adhesive. There is some deflection in the floor at mo which i'm hoping will be solved by screwing the boards down. Assuming it is rectified could i tile using bal fastflex directly to the chipboard on top of any existing lino adhesive? from what i've read the main reason not to tile directly to chipboard is that it swells when it comes into contact with water...so surely whatever adhesive is used it could fail if water comes into contact with the boards, is some kind of primer required first?

Adding 6mm hardibacker or no more ply would seem like the most sensible option if it weren't for the height problems...do either of these add any rigidness to the floor?

thanks :8:

 

[FreeD]

Hi all me again...

would also like to know a bit more about Caberdek moisture resistant chip board...

this product swells when it comes into contact with water? would it swell enouhgh to affect the tiles...what could happen?

the chipboard contains wax? what effect could this wax have on a tile installation?

thanks :8::8::8:

 

[doug boardley]

personally I'd use hardiebacker to be on the safe side, 6mm is hardly going to have to make you limbo dance under the door head:lol:

 

[FreeD]

Yea i agree doug...

but would like good answers to the 2 above questions so i know what to tell cutomers in future about the reasons not to tile directly to chipboard!!

 

[grumpygrouter]

Chipboard fails when it is wet and stays wet. Just getting wet from adhesive won't "blow" it. Hardie doesn't add strength to the floor as hardie recommend via a formula a maximum allowable deflection to allow hardie to be used on the floor. No More Ply claim to add equivalent strength to 15mm ply but as yet I personally have seen no documatation to back it up. To use either of these products the floor needs to be solid in the first place in my opinion!

 

[doug boardley]

Yea i agree doug...

but would like good answers to the 2 above questions so i know what to tell cutomers in future about the reasons not to tile directly to chipboard!!

sorry Freed, just saw an opportunity for a bit of humour:lol:

 

[DHTiling]

Chipboard is simply chippings/crap from the timber manufacturing industry and the surface structure is not stable enough to tile directly too IMHO...over board all the time for me..

 

[FreeD]

Ok so if the chipboard gets wet it stays wet...does it swell? causing the tiles to debond?

Does the wax cause the tiles to debond somehow?

 

[FreeD]

Dave not sure i see you point sorry i know this has been talked about over and over but if the chipboard is secured to joists set at 400 centres with screws is it not as strong as any other board?

is the problem not more to do with the expansion when wet or the wax?

 

[DHTiling]

As a surface coverage it is fine but to stick an adhesive to the surface then the only thing holding it is small fragments of chipboard and if lateral expansion or small deflection then these particles can break up.

As for the wax coating then is normally the green type chipboard and tile adhesive doesn't bond to it and then it deffo needs overboarding....

hope that helps better....to tile to chipboard imo isn't good....yes moisture can make it swell but that's not my main reason for not tiling to it..

 

[Time's Ran Out]

FreeD - Have you seen the plinths on kitchen units when the water has got into the unsealed bootom edge - they blow out to double their normal size and disintergrate.
So if you tile directly onto chipboard which is screwed into the joists and moisture from below or from the surface will make the edges swell first and possibly deflect in between the joists.
Any movement in this material will be shown on the joins between each sheet at either 600mm or 1200mm spaces and this movement will transfer through to the surface of the tile!
As suggested use the Hardie 6mm backer boards (Doug)to overboard accross the joints to eliminated this movement in the suface - but only again as suggested if there is no deflection (Grumpy) in the present chipboard flooring.
Got no idea about any wax in chipboard as i have never tiled directly onto it!.
Hope you may find this info Good - just off now to limbo up to bed:lol:.

Timeless John.:smilewinkgrin:

 

[FreeD]

lol thanks all very good info!! just got to translate it into English now so the customer understands! defo going to overboard with 6mm hardie much rather be safe than sorry...will make sure i sought out deflection first. Have a good weekend all...i'm off surfing tmw 🙂

 

[Time's Ran Out]

Is that because most of the posts in reply have come from us northerners or is your customer a foreign chappie!
Do they say break a leg when you go surfing or is that just wishful thinking as I'am at work!:lol:

John.

 

[FreeD]

lol nah its just that u'd need a degree in surveying or something :lol:

 

[FreeD]

ok had another thought say the moisture resistant chipboard does get wet from above/below and swells how is overboarding with hardibacker going to prevent the tiles from or grout form cracking because the deflection is still going to be transferred to the hardibacker and in turn the tiles as the hardibacker does not add any rigidity to the floor and is attached directly to the chipboard...surely a 18mm ply would have to be used? or no more ply possibly? something that is rigid enough to withstand deflection cause by moisture in the chipboard...i would say we are talking about a serious leak here! :dizzy2:

 

[Time's Ran Out]

FreeD - So what do YOU want to do!

You asked if it was okay to tile directly onto the chipboard floor after the deflection had been removed - NO.
You confirmed that 6mm backer board was the best option and it was confirmed it was - only onto a rigid floor.
If you want to replace the chipboard with 18mm+ plywood great but it should still be overborded or ditra matting before tiling for all the reasons previously given.
If its as serious a leak as you are anticipating - a river flood - the people wil move out, it'll take 6 months to dry out and the whole lot will be ripped out.

Timeless John.

 

[Perry]

You can tile directly to chipboard using 2 part green is not as good as the ordinary because of the wax but as Dave says you are best over boarding it 😛ete

 

[CBTC]

In regard to deflection / stability of the floor, the hardibacker may not necessarily add enough strength, no. Its up to you to determine how much movement and lack of background stability there is. In my experience where chipboard boarding is put down it is rarely ever soundly done - and that's where it is for a floating timber or carpet flooring over it. For tile work its a non starter a lot of the time, and overboarding and sometimes augmenting the batten or joisting structure is required first.
Boards are determined by their constituentency and process really, hence chipboard cheap and weak. Exterior grade ply expensive and strong. Various in between. Thicknesses are specific to job and material type.
In my view overboarding this as you describe would be a must. Use of Fast Flex or Ardex 7001 type adhesivesisnt going to solve the substrate problems on their own!
Good luck.

 

[smurf21]

In short whatever timber substrate is down screw solidly to remove deflection then overboard with a 6mm cementious board following manufacturers guidelines.
if the floor gets wet and through the tile and grout it will not effect the cement board it wont rot and will not force the tiles to delaminate:drool5:

 

[FreeD]

Thanks all.

Given the customer option of securing existing chipboard floor then overboarding with 6mm hardibacker...mainly so good bond for tiles and to protect against water ingress from above.

or rip out chipboard and replace with 18mm ply.

Use 2 part flexible adhesive on both installations with flex grout.

In my opinion one of these 2 options in this situation will be fine.

I've checked out other products

plastic ply - useless technical support installed no confidence in me in the product...one thing i did get from my conversation is that the product is not suitable over chipboard of any kind even if it has been secured to the joists. And that only Nicobond adhesives and grouts should be used. He repeated this phrase about 10 times 'we cannot be held liable' lol

No more ply - looks good but has been discontinued by my local supplier and replaced with plastic ply, not sure why yet.

I'm sticking with hardibackers for now...tried and tested! :hurray:

 

[smurf21]

No more ply - looks good but has been discontinued by my local supplier and replaced with plastic ply, not sure why yet.

Its because GRUMPY GROUTER keeps doubting the magical capabilities of this amazing product:yikes:

 

[grumpygrouter]

Its because GRUMPY GROUTER keeps doubting the magical capabilities of this amazing product:yikes:

LOL...I don't doubt it is a good product Smurf. I am sure it is, but I can not get it where I am to try it so can not pass judgement by way of use. It MAY WELL have such magical properties that it will replace 15mm ply strength for strength, but it seems the company are too shy to provide detailed documentary evidence to prove it. The only reference they make in this resepect is in their marketing literature, which is designed to sell the product as best as it can, and it seems to be doing just that.

As i have previously said, if independent tests are carried out that verifies the claim and is reported as such in writing, I will be the first to push the product in these forums as it could be the life saver scottish timber frame houses need for safe tiling.