Replacing Existing Floating Floor

[jmm]

I’m looking to lay porcelain tiles in a kitchen diner (~22m2). I have a floating floor, which is not suitable for tile. I’ve been quotes for Ditra, but Ditra is for horizontal movement. My current sub floor is:

- Bison Block and Beam.

- 20mm insulation

- DPM (blue plastic sheet)

- 18mm WBP tongue and groove

I’m planning on removing the WBP, DPM and insulation. And I don’t know if there is a DPM under the Bison.

I considered a bounded screed, but this is likely to be 40mm thick with no insulations (too cold). I only have 55mm from the Bison to the top of the tile.

So I’m looking to replace it with:

- Bison Block and Beam

- Ardex DPM 1 c (just encase)

- Marmox 40mm Multiboard with a flexible adhesive.

- Ditra

The Marmox (and Ditra) will form the vapour barrier to protect the tile.

Would this subfloor take tile? Does any see any problems?


Many thanks

 

[J Sid]

I would change the Marmox to
XP-PRO Boards
For cost reason's, and I have used it for the purpose you need it.
And unless you decide to use ufh I wouldn't use or see the need for Ditra.

Have you considered electric or wet ufh?

 

[White Room]

Usually block and beam is off the base and is suspended on the beams....

 

[jmm]

I also expect the block and bean to be suspended but I'm removing a DPM and feel I should put one back.

I've not considered UFH. Prefer to use the extra depth used by a UFH system for insulation and to ensure the floor doesn't move. I still like the idea of Ditra to create a vapour barrier and protect against horizontal movement. The room is 6m x 3m. So...

- Beam and Block
- Ardex DPM 1 c
- XP Pro Board
- Ditra
- Porcelain tiles

I would still use a flexible adhesive to bond the XP-Pro to the DPM and therefore ensuring its not a floating floor. And that the XP-Pro will not create a cold bridge?

 

[J Sid]

I also expect the block and bean to be suspended but I'm removing a DPM and feel I should put one back.

I've not considered UFH. Prefer to use the extra depth used by a UFH system for insulation and to ensure the floor doesn't move. I still like the idea of Ditra to create a vapour barrier and protect against horizontal movement. The room is 6m x 3m. So...

- Beam and Block
- Ardex DPM 1 c
- XP Pro Board
- Ditra
- Porcelain tiles

I would still use a flexible adhesive to bond the XP-Pro to the DPM and therefore ensuring its not a floating floor. And that the XP-Pro will not create a cold bridge?

XP-pro boards need priming on all sides and can then be stuck down to make a none floating floor.
If you use the Ditra as a vapour barrier tape the joints

 

[jmm]

XP-pro boards need priming on all sides and can then be stuck down to make a none floating floor.
If you use the Ditra as a vapour barrier tape the joints

With the Ditra I was considering using waterproof points both on the floor and up the walls (just behind the skirting boards). This would be like how my DPM is currently fitted.

Would not prime the floor rather than the board? I was thinking about using Ardex P4 primer on the DPM.

 

[J Sid]

Prime the floor with what Ardex and your adhesive company recommend.
Prime the boards to so adhesive will stick to it

 

[jmm]

Prime the floor with what Ardex and your adhesive company recommend.
Prime the boards to so adhesive will stick to it

What primer did you use for priming the boards?

 

[Just Rizzle]

take up every thing, tank out floor or apply 2 coats of sbr 1st coat 1/3 2nd coat at 90 degrees to first coat 1/1
leave to dry stick down 20mm wedi board lay another layer of 20 mm wedi at right angles to the 1st then tile on top. easy peasy.

 

[jmm]

take up every thing, tank out floor or apply 2 coats of sbr 1st coat 1/3 2nd coat at 90 degrees to first coat 1/1
leave to dry stick down 20mm wedi board lay another layer of 20 mm wedi at right angles to the 1st then tile on top. easy peasy.

What's the benefit from using two boards over 1 40mm board? Is this to remove the lateral movement or part of the waterproofing?

And are you suggesting wedi board to remove the need to prime the boards?

 

[Just Rizzle]

What's the benefit from using two boards over 1 40mm board? Is this to remove the lateral movement or part of the waterproofing?

And are you suggesting wedi board to remove the need to prime the boards?

by using 2 layers you strengthen the floor as your effectively laminating it and by using wedi better water protection and also no priming so job can be done faster.

 

[J Sid]

So your saying wedi board is not strong enough in one 40mm bit?
And that put sticking two 20mm boards down with the extra adhesive, fixing and mixing time is quicker and cheaper than priming with a roller and fixing one layer of 40mm board?
Well you learn something new on here every day

 

[Tile Shop]

The wedi is pretty strong. one single 40mm would be fine on rigid block and beam. Unless you weigh approximately 2 tonnes, then you may get a tiny bit of compression! Based on wedi's technical sheet.

Thats if i've got my rough calculations right.

Compression resistance of 0.25N per mm2 with the average adult foot has an area coverage of 31000 mm2 multiplied by 2 feet (in most cases) = 62000 mm2...... times 0.25N per mm2 = 24800N dead weight multiplied by 0.1019kg's per Newton = 2528 kg with both feet firmly planted although results may vary for walking, jumping or standing on one leg.

Ok, so I was half a tonne out! and thats if you're standing on the bare board. once its tiled, it'll spread the weight even more. Meaning you could burger yourself up to 10 tonnes. maybe more!

Would recommend this floor preperation to feeders!

 

[jmm]

The wedi is pretty strong. one single 40mm would be fine on rigid block and beam. Unless you weigh approximately 2 tonnes, then you may get a tiny bit of compression! Based on wedi's technical sheet.

Thats if i've got my rough calculations right.

Compression resistance of 0.25N per mm2 with the average adult foot has an area coverage of 31000 mm2 multiplied by 2 feet (in most cases) = 62000 mm2...... times 0.25N per mm2 = 24800N dead weight multiplied by 0.1019kg's per Newton = 2528 kg with both feet firmly planted although results may vary for walking, jumping or standing on one leg.

Ok, so I was half a tonne out! and thats if you're standing on the bare board. once its tiled, it'll spread the weight even more. Meaning you could burger yourself up to 10 tonnes. maybe more!

Would recommend this floor preperation to feeders!

I doubt that I'll be putting 2 tonnes on the floor (even with a quartz kitchen worktop). So I'm now going for...

- Beam and Block
- Ardex DPM 1 c (2 coats of sbr 1st coat 1/3 2nd coat at 90 degrees to first coat 1/1)
- Ardex P4 primer
- 40mm Wedi Board
- Ditra
- Porcelain tiles
- DPM plastic sheet on the walls

Does anyone disagree with this?

And can anymore recommended the flexi adhesive to stick the wedi down (should I keep with Ardex)?

 

[hmtiling]

Stick with ardex

 

[hmtiling]

Doesn't the Wedi board have decoupling properties?

 

[Just Rizzle]

the reason for using 2 x20 mm boards is this from my experience of kitchens the chances are you will have a load of pipe work running over the floor between the insulstion. the first layer you would run up to the pipe work and between it . the second layer at 90 degrees to the 1st bridges these gaps it also allows you to level the floor if the sub floor is uneven by using wedi there is no need for ditra as it effectively decouples and waterproofs so no need also for dpm plastic up the walls as the tanking takes care of that. I have done a couple of floors were ive used this method and done them both in a day.
another way would be to rip up floor cover with a dpm then screed out with 40mm semi dry screed and bed the tiles in using cement sbr slurry that's the way I would of done it 20 yrs ago and again all done in a day

 

[jmm]

the reason for using 2 x20 mm boards is this from my experience of kitchens the chances are you will have a load of pipe work running over the floor between the insulstion. the first layer you would run up to the pipe work and between it . the second layer at 90 degrees to the 1st bridges these gaps it also allows you to level the floor if the sub floor is uneven by using wedi there is no need for ditra as it effectively decouples and waterproofs so no need also for dpm plastic up the walls as the tanking takes care of that. I have done a couple of floors were ive used this method and done them both in a day.
another way would be to rip up floor cover with a dpm then screed out with 40mm semi dry screed and bed the tiles in using cement sbr slurry that's the way I would of done it 20 yrs ago and again all done in a day

I have 4 pipes: 1x water, 2x waste and 1x capped gas. The two board solution is interesting. Ideally I want to lay the least amount of board possible (i.e. once at 40mm). But this will difficulties around the pipes.

DPM on the walls too instead of a plastic sheet then.

Removing the need for Ditra would save several hundred pounds. I guessing the foam acts as the decoupling between the two backer boards.

Given the price of Wedi, would going back to (cheaper) Marmox board do the same job? The specification seem very similar (if anything the Marmox seems stronger).

 

[Just Rizzle]

I have 4 pipes: 1x water, 2x waste and 1x capped gas. The two board solution is interesting. Ideally I want to lay the least amount of board possible (i.e. once at 40mm). But this will difficulties around the pipes.

DPM on the walls too instead of a plastic sheet then.

Removing the need for Ditra would save several hundred pounds. I guessing the foam acts as the decoupling between the two backer boards.

Given the price of Wedi, would going back to (cheaper) Marmox board do the same job? The specification seem very similar (if anything the Marmox seems stronger).

ive never used marmx so cant comment but if there like wedi ie water proof then yes

 

[jmm]

ive never used marmx so cant comment but if there like wedi ie water proof then yes

Seems to be a similar spec but half the price. So finally...

- Beam and block
- Ardex DPM 1 C
- Ardex P4 primer
- Ardex x7G Plus adhesive (C2)
- 30mm (or 20mm + 10mm) Marmox board with fibre tape
- Ardex x7 Plus adhesive
- Tile

 

[bcd-87]

I have 4 pipes: 1x water, 2x waste and 1x capped gas. The two board solution is interesting. Ideally I want to lay the least amount of board possible (i.e. once at 40mm). But this will difficulties around the pipes.

DPM on the walls too instead of a plastic sheet then.

Removing the need for Ditra would save several hundred pounds. I guessing the foam acts as the decoupling between the two backer boards.

Given the price of Wedi, would going back to (cheaper) Marmox board do the same job? The specification seem very similar (if anything the Marmox seems stronger).

Are you the tiler of the home owner ?