Marble onto 6mm HardiBacker?

[woof]

Hello All,
Thanks for your help in the past - the granite floor I laid in our small bathroom is looking great. I used a flexible adhesive for this - one of the expensive BAL rubber ones I think - and no movement.

My next project is the kitchen floor. Much bigger expanse - 5.4m x 3m, so I was not going to risk the adhesive direct on the old (1960s build - but secure) T&G floor. I was thinking and from what I have read on here
1; Screw down floor boards more to ensure movement is restricted
2. Lay 6mm Hardibacker
3. Lay down marble - using flexible adhesive.

So is this sensible? I want to keep the minimum height increase (the tiles are 15mm thick :yikes: ) so am hoping 6mm is sufficient if (1) is done properly.
How do you secure the backer - screws only or adhesive too?

Thanks in advance.
Mark

 

[Dan]

You're right in what you say.... I think. (Wait for more advice, I don't actually tile any more to be honest).

Though I've read myself that you can lift the floorboards and lay 18mm ply down instead, screwed at 300mm centres, and then tile onto that with a two-part flex cement based adhesive. (Please do wait for more advice though - wouldn't want to contribute to that job being re-done again!!)

 

[brinkley]

flexible adhesive to fill any voids in the floor and screws make sure the floor is completely solid first though woof

 

[woof]

flexible adhesive to fill any voids in the floor and screws make sure the floor is completely solid first though woof

Just read the installation instructions and did not realise you also use flexible tile adhesive to lay the backer board - is that correct? Do you also need the jointing tape - or would filling in the joints with this adhesive suffice?

Do I have that correct is is this all overkill?

Secondly - you are in East Sussex too! Enjoying the late August summer rain? Seems the weather is gearing up for the bank holiday!

 

[brinkley]

i always tape the joints and skim over the with the adhesive .
yes the weather is not gooood

 

[doug boardley]

if you're going to use marbe again, I'd also use a decoupling membrane

 

[woof]

if you're going to use marbe again, I'd also use a decoupling membrane

Ohhhhhhhh . I thought these sorts of things were for bathrooms. THis is for a kitchen - is it still required? I suppose for the once in 3year flood from having to force open the washing machine.....

So what options are there (been reading on here ditra? Ci?) - which is thinnest and cheapest?

Then is it -
Firmly screwed T&G floorboards
adhesive (3mm)
backer (6mm)
decoupling membrane ?mm + more adhesive?
adhesive 3mm
tiles (15mm)
27mm already + membrane! Won't need step ladders to paint the ceiling!

On another topic - maybe I can save 3mm using the no more ply that has somewhat divided opinion as this does not use flexible adhesive?

Thanks for the advice and suggestions

 

[doug boardley]

Ohhhhhhhh . I thought these sorts of things were for bathrooms. THis is for a kitchen - is it still required? I suppose for the once in 3year flood from having to force open the washing machine.....

So what options are there (been reading on here ditra? Ci?) - which is thinnest and cheapest?

Then is it -
Firmly screwed T&G floorboards
adhesive (3mm)
backer (6mm)
decoupling membrane ?mm + more adhesive?
adhesive 3mm
tiles (15mm)
27mm already + membrane! Won't need step ladders to paint the ceiling!

On another topic - maybe I can save 3mm using the no more ply that has somewhat divided opinion as this does not use flexible adhesive?

Thanks for the advice and suggestions

that'll probably be the wp tanking membrane you're thinking about Woof,uncouple will probably raise the height by less than 5mm imo if you're using natural stone, it's something I'd strongly recommend.

 

[woof]

Me again,

Decoupling membrane. Is Durabase CI matting what we are talking about? I have been trying to contact wetdecs to see if he sells the stuff but he doesn't seem to have been around the last week, so probably on holidays. I am looking to get cracking end of next week so wanted to begin to get materials sourced so wanted to be sure that Durabase CI is a sensible option here. Also was planning to go with no more ply under instead of Hardibacker as this will save one 3mm layer height increase.

Comments or advice please

 

[grumpygrouter]

Me again,

Decoupling membrane. Is Durabase CI matting what we are talking about? I have been trying to contact wetdecs to see if he sells the stuff but he doesn't seem to have been around the last week, so probably on holidays. I am looking to get cracking end of next week so wanted to begin to get materials sourced so wanted to be sure that Durabase CI is a sensible option here. Also was planning to go with no more ply under instead of Hardibacker as this will save one 3mm layer height increase.

Comments or advice please

I'm not sure you are right in your assumpton. The adhesive under the hardie is to fill in any voids that may occur from not having flat boards. the flatter the floor initially, the less adhesive you will need. NMP with it's polyurethane adhesive will have the same function, perhaps to a lesser extent.

I know you are concerned for height etc but when you spend good money on expensive stone, it is in your best interest to provide the best base for your tiles. In my opinion with marble, a decoupling membrane is absolutely essential.

 

[woof]

Ok so all stuff in place now. Room cleared, concrete plinth built through the suspended floor (don't ask!), skirting off,electrics rerouted, plumbing diverted and floor boards about to be screwed down.
23 nomoreply boards and durabase CI at the ready!:yikes:

Now when these are down what trowel should I use? SInce the floor will be level - hoping that a smaller notch might be possible? Should I get a few different sizes and test to see which trowel gives me complete coverage when twisting and then lifting or is there a more scientific method to calculate the correct size?

Thanks in advance

 

[faithhealer]

10mm rad floor trowel, back skim every tile with addy