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

[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

[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

[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]

Originally Posted by 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!!

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

[Dave]

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?

[Dave]

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..

[timeless john]

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.

Timeless John.

[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

[timeless john]

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!

John.

[FreeD]

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