Hi guys,

I have recently replaced my rotten bathroom floorboards with extra noggins and joists and overboarded with 18mm WBP.

Can anybody advise the correct adhesive/procedure for laying 600x400x12mm Travertine tiles on this substrate.

Many thanks,
Will.

Assuming that there is no deflection on the floor, single part flexible to stick a decoupling membrane, then a white single flex to stick the trav down and back skim the tiles

you could ditch the floor boards altogether and use 25/28mm ply

how big is the room?

Thanks for the response guys, on reflection I dont think I have been very clear. I now have no floor boards just the 18mm WBP on the strengthened joists. The area to be tiled is approximately 3M2. The floor is now flat, level and secure. Should I be using "Ditra" on a roll or cement hardibacker or anything like that?
Thanks,Will .

on a small area like that i wouldn't bother with ditra but i would use 25mm ply rather than the 18mm

You could over board with hardi or similar as its a better surface to tile to but to be honest as long as there is no deflection it should be fine.

Did you prime the UNDERSIDE of the ply before it was fixed? Its common practise to do that to stop any moisture getting to the underside.

Do you know what centres the joists were? 600mm or 450mm?

Originally Posted by williamraff

Thanks for the response guys, on reflection I dont think I have been very clear. I now have no floor boards just the 18mm WBP on the strengthened joists. The area to be tiled is approximately 3M2. The floor is now flat, level and secure. Should I be using "Ditra" on a roll or cement hardibacker or anything like that?
Thanks,Will .

IMO Whitebeam reply is the way I'd go.
Either of your options above will be fine - just make sure to cover any joints in the plywood as 100% it will crack down those lines.
You have to be confident that your 18mm plywood is offering no deflection/movement.

Cheers guys,

the floor has very little deflection. I sistered all the existing joists and tied them into the walls, the joist centres are 450mm and I have added extra noggins and cross bracing.
Hopefully Whitbeams advice/approach wil be sufficient but I am afraid I did not seal the WBP before puting down . Is it worth ripping it out again to be safe?
Thanks,Will.

Sounds like your doing a belt and braces job

As for sealing the back, its up to you. I dont think many people have sealed the back in the past as they werent aware it needed doing. I for one wasnt aware of it for a long time and have had no problems as yet. If it was groudnfloor over a damp void then id advise yes but if its upstairs ill leave the decision to you.

Thanks, I dont often trust to luck but I think I will in this case. My life would not be worth living if I pulled the bathroom floor up again.

use the latex plus with your keraquik,,you stated in another post that mapei tech advised you to do this,probably meaning you wont be covered if you use water to mix it,,this is the route id go

Thanks for that, I have only just joined this forum and the advice received so far has been invaluable

Hi Will..

When using stone over timber IMO it is wise to use an anti fracture membrane like ditra.. thermal stress from the ply can cause hairline cracks at the board joints..

All things considered, I think I will actually go with the Ditra. In terms of percentage of overall budget it does not make that much difference and given the use the bathroom is going to get - six children, jacuzzi bath and separate shower enclosure and the encumbant co - efficients of expansion and contraction; I think it is well worth the extra short term expenditure for long term peace of mind

Cheers,Will.

If it was my bathroom, I would be laying ditra/durabase too!

That's it, everything orderd and paid for; picking materials up tomorrow.
Wish me luck guy's, I am going in!

Originally Posted by williamraff

All things considered, I think I will actually go with the Ditra. In terms of percentage of overall budget it does not make that much difference and given the use the bathroom is going to get - six children, jacuzzi bath and separate shower enclosure and the encumbant co - efficients of expansion and contraction; I think it is well worth the extra short term expenditure for long term peace of mind

Cheers,Will.

Best move you will make..

Originally Posted by williamraff

That's it, everything orderd and paid for; picking materials up tomorrow.
Wish me luck guy's, I am going in!

Good luck and look forward to the pics..

Good luck Will, please keep us posted. Maybe some pics