Just covered a floor in 18mm waterproof ply - as per recommendation of the Weber Tiling Manual. I've sealed the edges and bottom of the ply with a Primer (Weber AD250 in this case). And was wondering what to seal the top of the ply with?

Its being covered with a heating mat, then Travertine. I'll probably use Self Leveling over the mat, then tile on that with some Weber SPF Rapid.

So I called Weber and asked their advice as to which primer to use on top of the ply - and the answer was - NONE? They suggested that using a primer would actually act as a decoupling membrane?? Not too confusing - I thought that was what PVA did and was why we must use a primer instead, because the primer soaked into the wood and truly primed.

Is the man from del monte (weber) correct? Do I just put the self levelling (and or spf) direct onto the WBP?

Paul

A lot of manufacturers dont say prime the face of ply.
I am more concerned with using Travertine over UFH without ditra or Dural Ci.

Originally Posted by Sir Ramic

A lot of manufacturers dont say prime the face of ply.
I am more concerned with using Travertine over UFH without ditra or Dural Ci.

I'm with you on this one Neale.

wot self leveller will you be using..?....not many suitable for use over wood and ufh..

Originally Posted by Dave

wot self leveller will you be using..?....not many suitable for use over wood and ufh..

Mapei Fibreplan ?

Ply, UFH, and Travertine . I think there's a whole lot of risks there and can't believe that a manufacturer is recommending this 'toxic mix'.

Andrew

I've used trav over piped uhf, (no ditra membrane etc )isocrete screed, primed with sbr, spf adhesive and had no problems.:if I'm correct in thinking bal 2 part flexi recommend no primer,gaz could probably confirm/deny this?

done it before,12mm ply,screwed at 150mm centers,primed,UHF,laid tiles onto FASTFLEX,Mint job,had 2 more houses to do for the same guy,just be careful with your serater over the UFH

Ply should not be primed if using Fast Flex. Back and edges should be sealed with SBR before screwing down.

Self Leveler will probably be Dunlop - as its nice and cheap

from CTD - about £12 a bag. And is simply to cover the devi mat, so I don't nick it.

Paul

Originally Posted by grumpygrouter

Ply should not be primed if using Fast Flex. Back and edges should be sealed with SBR before screwing down.

The ply was primed as it was supplied by the customer and he insisted it had to be primed.Yes the sides and back were sealed,but the customer was adamant he had been told to prime the ply,actually the priming agent was supplied by the distributor,i had not seen it before or since,it did contain "LATEX" so maybe that was why it had to be used.
Maybe GAZ could give some info on this.I am going back around 10 yrs ago

Doesn't matter if you primed it or not using Fastflex - call BAL and I'm pretty sure they'll tell you that the installation is a 'suspect one' as they just don't recommend UFH cables over ply unless you introduce an insulation / tile backer board. Primer or not - they'll not be interested if it had failed ........... and I would have thought the dictating customer would have towed the same line and blamed you. Come to think of it, the distributer would have probably blamed you too! But, on this occassion, the floor didn't fail so maybe BAL don't know the power of their own products

Originally Posted by Sir Ramic

A lot of manufacturers dont say prime the face of ply.
I am more concerned with using Travertine over UFH without ditra or Dural Ci.

Well guys sorry to say I have laid 1000s m2 Travertine on underfloor heating on wood on concrete without Ditra or Dural and not one has come back and bite me on the ass. End of day what is the point of all the manufactors of quality adhesives making flexible adhesive that does the job stated on the bag.

I know I have had this dicussion before about new builds etc but it is an expense that really does not need to be passed onto my customers.

My opinion and each is welcome to theirs

Gary

Originally Posted by Highlander

Well guys sorry to say I have laid 1000s m2 Travertine on underfloor heating on wood on concrete without Ditra or Dural and not one has come back and bite me on the ass. End of day what is the point of all the manufactors of quality adhesives making flexible adhesive that does the job stated on the bag.

I know I have had this dicussion before about new builds etc but it is an expense that really does not need to be passed onto my customers.

My opinion and each is welcome to theirs

Gary

Sounds good to me. I like your logic. After all, 18mm ply screwed down, over a floor of 18mm boards, which are screwed down as well, is a pretty damn stable surface. Sure its wood, so there will be movement. But surely that's what the flexible adhesive is for - as you quite rightly say.

I could always just lay concrete on their 1st floor - now there's a thought

Paul

Originally Posted by Highlander

Well guys sorry to say I have laid 1000s m2 Travertine on underfloor heating on wood on concrete without Ditra or Dural and not one has come back and bite me on the ass. End of day what is the point of all the manufactors of quality adhesives making flexible adhesive that does the job stated on the bag.

I know I have had this dicussion before about new builds etc but it is an expense that really does not need to be passed onto my customers.

My opinion and each is welcome to theirs

Gary

with you on all points there Gary

Originally Posted by Highlander

Well guys sorry to say I have laid 1000s m2 Travertine on underfloor heating on wood on concrete without Ditra or Dural and not one has come back and bite me on the ass. End of day what is the point of all the manufactors of quality adhesives making flexible adhesive that does the job stated on the bag.

I know I have had this dicussion before about new builds etc but it is an expense that really does not need to be passed onto my customers.

My opinion and each is welcome to theirs

Gary

Did you use a particular addy Gary and do you have your own particular methods of fixing?