Limestone tile on chipboard - advise please?

[robthebubble]

Hi all....been looking at this forum and seen some great advise however I could do with some help!

I'm about to do a full bathroom refit and what I want to do is lay a limestone floor with underfloor heating. Currently the floor is 18mm chipboard nailed to the joists...I suspect this is unsultable to tile on to. My thoughts were to add 6mm 'no more ply' and screw (and use adhesive) every 300mm.

I want to keep the floor level as low as possible as I don't want the usual "step/lip" at the door. I will also be using the following as recommended by the tile supplier:
Dunlop Universal Bonding Agent
Dunlop Set Fast Plus White Adhesive
Dunlop Limestone Grout
Dunlop Flexible Additive

So, should I be OK with the going down the no more ply route or should I take up the whole floor and put ply down? (although the shipboard goes under the studwork!)

Cheers

Rob

[Dave]

As long as the floor is SOLID then it will be fine.....personaly i would also use an uncoupling membrane with it being limestone this will prevent any expansion causing cracks in the tiles.......I use Ditra........

[grumpygrouter]

As long as the floor is SOLID then it will be fine.....personaly i would also use an uncoupling membrane with it being limestone this will prevent any expansion causing cracks in the tiles.......I use Ditra........

I agree, Ditra for me too!

[Pawelzik]

...or Schlueters´s Kerdi matting if less floor height is wanted. That should work too.

[robthebubble]

Thanks for the response. So with Kerdi I put a thin layer of adhesive down, then the kerdi then the under floor heating or do I put the underfloor heating down then the adhesive, then Kerdi then adhesive?

Just want to make sure I get it right!

Cheers

Rob

[Pawelzik]

... or do I put the underfloor heating down then the adhesive, then Kerdi then adhesive...

This way.

[robthebubble]

Superb...thanks! Although, the cost is quite expensive...£58 for 5m2!

[grumpygrouter]

Superb...thanks! Although, the cost is quite expensive...£58 for 5m2!

Not as costly as laying your limestone and having to take it up again when it has cracked!

Personally have not heard of using Kerdi as an isolator but I would not contradict Pawelzic as he has been in the industry a lot longer than I have. I do know for definate that Ditra is designed for isolation and it is the one I would use if it was my bathroom. I would also opt for Ardex-flex 7001 in white as you have a timber floor.

[Dave]

Kerdi is a crack bridging membrane and water proofer and Ditra is crack bridging and isolation membrane......personally i would use the ditra as it will isolate the tiles from the substrate the Kerdi won't.....

[robthebubble]

Kerdi is a crack bridging membrane and water proofer and Ditra is crack bridging and isolation membrane......personally i would use the ditra as it will isolate the tiles from the substrate the Kerdi won't.....

Looks like I'll put some Kerdi on the walls and Ditra on the floor....should do the job just fine then!

Thanks for the advise even if it is costing me more money! but at least it's better in the long run as knowing my luck the tiles will start to come up!

Great forum by the way...everyone seem really friendly and helpful!

Rob

[wetdec]

Hi Rob

As you are going to use Kerdi & Ditra we use an alternative that does exactly the same thing if your interested.

5m2 of Durabase WP in place of Kerdi

5m2 of Durabase CI matting in place of Ditra

5m jointing tape


The above would be £110 delivered to your door m8


tiler

..

[robthebubble]

Hi Rob

As you are going to use Kerdi & Ditra we use an alternative that does exactly the same thing if your interested.

5m2 of Durabase WP in place of Kerdi

5m2 of Durabase CI matting in place of Ditra

5m jointing tape


The above would be £110 delivered to your door m8


tiler

..

Thanks for the offer but I've placed the order already and it works out at the same price because I have already paid for delivery of the tiles etc.