Help!: Understood that floating floor is a no no, but what should replace it?

[GarryMartin]

I've been having an offline conversation with Sir Ramic (who has been excellent) and he suggested I bring my problem to the wider TilersForums group.

We're about to start a kitchen refit in a 13 year-old house. We'd like to tile the entire downstairs excluding the main living room - so the hall, kitchen, dining (play) room, utility and cloakroom; about 52 square metres.

However, there is a floating floor - 18mm chipboard on top, then 25mm polystyrene, vapour barrier and a concrete floor. I've read most all the floating floor posts on the board so know that I shouldn't expect miracles and that if my heart is set on tiles, then the floating floor has to go.

Question is, what should I replace it with?

It seems to make sense that I should keep the thermal insulation properties of the polystyrene if at all possible, especially as I'll be losing the insulative properties of underlay and carpet in some of the areas and I'm not planning on underfloor heating, but how do I do that?

I've seen mention of ripping the floating floor out, battening out, insulating between the battens and then laying 18mm+ plywood on top, but presumably that requires the battens to be fixed to the concrete, thereby breaching the vapour barrier?

I've also seen mention of using 40mm Marmox or Ekoboard fixed directly to the concrete. It seems the former can be used as a vapour barrier, and although I'm not sure whether that is the same for the latter, I'm also not sure if a vapour barrier is needed if I'm tiling?

I'm personally drawn to the Marmox/Ekoboard option as although it seems superficially more expensive than battening out, insulating, and putting down plywood, it appears simpler and less labour intensive.

Bottom line; I'm looking for the option that professional tilers like you guys would be happiest tiling on that maintains or improves on the limited thermal insulation I already have - something I can convince Sir Ramic to tile onto as he's not at all keen on floating floors...

[Del W]

Welcome to TF.Cant help you on this as i have not dealt with a floating floor,im sure youll get an answer later.

[timeless john]

Mr Martin - I'am not trying to be difficult and I understand your predicament - but why do you not go with the experience and advice of Sir Ramic!
He will have given you the options as he prefers and as he will be responsible for the completed project - you must accept that his way is the best way.
It would not be for me to offer an alternative method without a site visit or to be in possession of all the information available, so at this stage - I'am out

Good luck

[GarryMartin]

Mr Martin - I'am not trying to be difficult and I understand your predicament - but why do you not go with the experience and advice of Sir Ramic!
He will have given you the options as he prefers and as he will be responsible for the completed project - you must accept that his way is the best way.
It would not be for me to offer an alternative method without a site visit or to be in possession of all the information available, so at this stage - I'am out

Hi Timeless John - thanks for your reply but you misunderstand; it was Sir Ramic that suggested I should post on here to garner the wider views of the community.

I have absolutely no intention of disregarding any advice he may give me and am really happy that his first response was to turn the job down rather than tile over the floating floor with all the possible future failure scenarios that brings. He's suggested that he doesn't normally get involved in "preparation" so I'm just looking for the best options that would leave Sir Ramic or other professional tilers with a floor they would be happy to tile.

[Stewart]

I've gone the Marmox route several times with great success and is my preferred method when dealing with floating floors. I usually tape the joints and slc the floor too, depending on the size of area..... Ideally the best way would be to screed the floor after removing the floating one, but with the time constraints that are usually in place, I go with Marmox.

[GarryMartin]

Thanks for your reply Stewart. I hope you don't mind if I ask some additional questions?

I usually tape the joints and slc the floor too, depending on the size of area.....

It's about 52sqm in total - the entire downstairs except for the living room.

If I've understood the Marmox technical descriptions correctly and the posts on this forum, putting Marmox down on to a concrete floor is generally achieved using a flexible tile adhesive - is that your preferred method? You mention that you also usually tape the joints (which seems to be recommended) and use Self-Levelling Compound too. How do I determine whether SLC should be used? I know this is going to sound like a stupid question, but does it depend just how level the existing concrete is to start with? Is there a point at which the flexible adhesive directly on to the concrete won't work and SLC first becomes a no-brainer?

I've assumed 40mm Marmox boards would be suitable for replacing 18mm chipboard with 25mm insulation to maintain the approximate finished floor height with the area that will remain carpeted. Is that about right? Presumably this would change depending on what depth of SLC was needed?

Ideally the best way would be to screed the floor after removing the floating one, but with the time constraints that are usually in place, I go with Marmox.

Wouldn't I lose the small amount of thermal insulation I currently have if the floor is screeded? If this is the best way though, what time constraints should I be aware of? If I'm able to disconnect the "preparation" work from the tiling work, is this a better solution than the Marmox boards?

Thanks again for taking the time to respond.

[Sir Ramic]

Hello, for insulation purposes the Marmox would be the best route. It comes in various thickness's to suit your need. As I stated to yourself its not a method I am over familiar with. It obviously must be fine as its a favoured method by others. usually when I get called into a job it will already be prepped.
When you take the original floor up you may not be left with a level sub floor, therefore if Marmox is fixed down with flexible tile adhesive then you will probably still have an out of level floor and thats where the SLC would come into play.
This route is a fast track method as stated above, less mess but not quite sure on cost effectiveness over screeding.
While I do quite regularly lay onto 10mm marmox for UFH purposes I have only done a few floors like yours in the last few years.
I suggested asking on the forums to see other opinions or better suggestions.